IDLWAVE

3.1 Lesson I: Development Cycle

The purpose of this tutorial is to guide you through a very basic development cycle using IDLWAVE. We will paste a simple program into a buffer and use the shell to compile, debug and run it. On the way we will use many of the important IDLWAVE commands. Note, however, that IDLWAVE has many more capabilities than covered here, which can be discovered by reading the entire manual, or hovering over the shoulder of your nearest IDLWAVE guru for a few days.

It is assumed that you have access to Emacs with the full IDLWAVE package including online help. We also assume that you are familiar with Emacs and can read the nomenclature of key presses in Emacs (in particular, C stands for CONTROL and M for META (often the ALT key carries this functionality)).

Open a new source file by typing:

C-x C-f tutorial.pro RET

A buffer for this file will pop up, and it should be in IDLWAVE mode, indicated in the mode line just below the editing window. Also, the menu bar should contain ‘IDLWAVE’.

Now cut-and-paste the following code, also available as tutorial.pro in the IDLWAVE distribution.

function daynr,d,m,y
  ;; compute a sequence number for a date
  ;; works 1901-2099.
  if y lt 100 then y = y+1900
  if m le 2 then delta = 1 else delta = 0
  m1 = m + delta*12 + 1
  y1 = y * delta
  return, d + floor(m1*30.6)+floor(y1*365.25)+5
end

function weekday,day,month,year
  ;; compute weekday number for date
  nr = daynr(day,month,year)
  return, nr mod 7
end

pro plot_wday,day,month
  ;; Plot the weekday of a date in the first 10 years of this century.
  years = 2000,+indgen(10)
  wdays = intarr(10)
  for i=0,n_elements(wdays)-1 do begin
      wdays[i] =  weekday(day,month,years[i])
  end
  plot,years,wdays,YS=2,YT="Wday (0=Sunday)"
end

The indentation probably looks funny, since it’s different from the settings you use, so use the TAB key in each line to automatically line it up (or, more quickly, select the entire buffer with C-x h, and indent the whole region with C-M-\). Notice how different syntactical elements are highlighted in different colors, if you have set up support for font-lock.

Let’s check out two particular editing features of IDLWAVE. Place the cursor after the end statement of the for loop and press SPC. IDLWAVE blinks back to the beginning of the block and changes the generic end to the specific endfor automatically (as long as the variable idlwave-expand-generic-end is turned on; see Lesson II: Customization). Now place the cursor in any line you would like to split and press M-RET. The line is split at the cursor position, with the continuation ‘$’ and indentation all taken care of. Use C-/ to undo the last change.

The procedure plot_wday is supposed to plot the day of the week of a given date for the first 10 years of the 21st century. As in most code, there are a few bugs, which we are going to use IDLWAVE to help us fix.

First, let’s launch the IDLWAVE shell. You do this with the command C-c C-s. The Emacs window will split or another window will popup to display IDL running in a shell interaction buffer. Type a few commands like print,!PI to convince yourself that you can work there just as well as in a terminal, or the IDLDE. Use the arrow keys to cycle through your command history. Are we having fun now?

Now go back to the source window and type C-c C-d C-c to compile the program. If you watch the shell buffer, you see that IDLWAVE types ‘.run "tutorial.pro"’ for you. But the compilation fails because there is a comma in the line ‘years=...’. The line with the error is highlighted and the cursor positioned at the error, so remove the comma (you should only need to hit Delete!). Compile again, using the same keystrokes as before. Notice that the file is automatically saved for you. This time everything should work fine, and you should see the three routines compile.

Now we want to use the command to plot the day of the week on January 1st. We could type the full command ourselves, but why do that? Go back to the shell window, type ‘plot_’ and hit TAB. After a bit of a delay (while IDLWAVE initializes its routine info database, if necessary), the window will split to show all procedures it knows starting with that string, and plot_wday should be one of them. Saving the buffer alerted IDLWAVE about this new routine. Click with the middle mouse button on plot_wday and it will be copied to the shell buffer, or if you prefer, add ‘w’ to ‘plot_’ to make it unambiguous (depending on what other routines starting with ‘plot_’ you have installed on your system), hit TAB again, and the full routine name will be completed. Now provide the two arguments:

plot_wday,1,1

and press RET. This fails with an error message telling you the YT keyword to plot is ambiguous. What are the allowed keywords again? Go back to the source window and put the cursor into the “plot” line and press C-c ?. This shows the routine info window for the plot routine, which contains a list of keywords, along with the argument list. Oh, we wanted YTITLE. Fix that up. Recompile with C-c C-d C-c. Jump back into the shell with C-c C-s, press the UP arrow to recall the previous command and execute again.

This time we get a plot, but it is pretty ugly: the points are all connected with a line. Hmm, isn’t there a way for plot to use symbols instead? What was that keyword? Position the cursor on the plot line after a comma (where you’d normally type a keyword), and hit M-Tab. A long list of plot’s keywords appears. Aha, there it is, PSYM. Middle click to insert it. An ‘=’ sign is included for you too. Now what were the values of PSYM supposed to be? With the cursor on or after the keyword, press M-? for online help (alternatively, you could have right clicked on the colored keyword itself in the completion list). A browser will pop up showing the HTML documentation for the PYSM keyword. OK, let’s use diamonds=4. Fix this, recompile (you know the command by now: C-c C-d C-c), go back to the shell (if it’s vanished, you know what to do: C-c C-s) and execute again. Now things look pretty good.

Let’s try a different day. How about April fool’s day?

plot_wday,1,4

Oops, this looks very wrong. All April Fool’s days cannot be Fridays! We’ve got a bug in the program, perhaps in the daynr function. Let’s put a breakpoint on the last line there. Position the cursor on the ‘return, d+...’ line and press C-c C-d C-b. IDL sets a breakpoint (as you see in the shell window), and the break line is indicated. Back to the shell buffer, re-execute the previous command. IDL stops at the line with the breakpoint. Now hold down the SHIFT key and click with the middle mouse button on a few variables there: ‘d’, ‘y’, ‘m’, ‘y1’, etc. Maybe d isn’t the correct type. CONTROL-SHIFT middle-click on it for help. Well, it’s an integer, so that’s not the problem. Aha, ‘y1’ is zero, but it should be the year, depending on delta. Shift click ‘delta’ to see that it’s 0. Below, we see the offending line: ‘y1=y*delta...’ the multiplication should have been a minus sign! Hit q to exit the debugging mode, and fix the line to read:

y1 = y - delta

Now remove all breakpoints: C-c C-d C-a. Recompile and rerun the command. Everything should now work fine. How about those leap years? Change the code to plot 100 years and see that every 28 years, the sequence of weekdays repeats.

3.2 Lesson II: Customization

Emacs is probably the most customizable piece of software ever written, and it would be a shame if you did not make use of this to adapt IDLWAVE to your own preferences. Customizing Emacs or IDLWAVE is accomplished by setting Lisp variables in the .emacs file in your home directory—but do not be dismayed; for the most part, you can just copy and work from the examples given here.

Let’s first use a boolean variable. These are variables which you turn on or off, much like a checkbox. A value of ‘t’ means on, a value of ‘nil’ means off. Copy the following line into your .emacs file, exit and restart Emacs.

(setq idlwave-reserved-word-upcase t)

When this option is turned on, each reserved word you type into an IDL source buffer will be converted to upper case when you press SPC or RET right after the word. Try it out! ‘if’ changes to ‘IF’, ‘begin’ to ‘BEGIN’. If you don’t like this behavior, remove the option again from your .emacs file and restart Emacs.

You likely have your own indentation preferences for IDL code. For example, some may prefer to indent the main block of an IDL program slightly from the margin and use only 3 spaces as indentation between BEGIN and END. Try the following lines in .emacs:

(setq idlwave-main-block-indent 1)
(setq idlwave-block-indent 3)
(setq idlwave-end-offset -3)

Restart Emacs, and re-indent the program we developed in the first part of this tutorial with C-c h and C-M-\. You may want to keep these lines in .emacs, with values adjusted to your liking. If you want to get more information about any of these variables, type, e.g., C-h v idlwave-main-block-indent RET. To find which variables can be customized, look for items marked ‘User Option:’ throughout this manual.

If you cannot seem to master this Lisp customization in .emacs, there is another, more user-friendly way to customize all the IDLWAVE variables. You can access it through the IDLWAVE menu in one of the .pro buffers, menu item Customize->Browse IDLWAVE Group. Here you’ll be presented with all the various variables grouped into categories. You can navigate the hierarchy (e.g., ‘IDLWAVE Code Formatting->Idlwave Abbrev And Indent Action->Idlwave Expand Generic End’ to turn on END expansion), read about the variables, change them, and “Save for Future Sessions”. Few of these variables need customization, but you can exercise considerable control over IDLWAVE’s functionality with them.

You may also find the key bindings used for the debugging commands too long and complicated. Often we have heard complaints along the lines of, “Do I really have to go through the finger gymnastics of C-c C-d C-c to run a simple command?” Due to Emacs rules and conventions, shorter bindings cannot be set by default, but you can easily enable them. First, there is a way to assign all debugging commands in a single sweep to another simpler combination. The only problem is that we have to use something which Emacs does not need for other important commands. One good option is to execute debugging commands by holding down CONTROL and SHIFT while pressing a single character: C-S-b for setting a breakpoint, C-S-c for compiling the current source file, C-S-a for deleting all breakpoints (try it, it’s easier). You can enable this with:

(setq idlwave-shell-debug-modifiers '(shift control))

If you have a special keyboard with, for example, a SUPER key, you could even shorten that:

(setq idlwave-shell-debug-modifiers '(super))

to get compilation on S-c. Often, a modifier key like SUPER or HYPER is bound or can be bound to an otherwise unused key on your keyboard; consult your system documentation.

You can also assign specific commands to keys. This you must do in the mode-hook, a special function which is run when a new IDLWAVE buffer gets set up. The possibilities for key customization are endless. Here we set function keys f4-f8 to common debugging commands.

;; First for the source buffer
(add-hook 'idlwave-mode-hook
   (lambda ()
    (local-set-key [f4] 'idlwave-shell-retall)
    (local-set-key [f5] 'idlwave-shell-break-here)
    (local-set-key [f6] 'idlwave-shell-clear-current-bp)
    (local-set-key [f7] 'idlwave-shell-cont)
    (local-set-key [f8] 'idlwave-shell-clear-all-bp)))
;; Then for the shell buffer
(add-hook 'idlwave-shell-mode-hook
   (lambda ()
    (local-set-key [f4] 'idlwave-shell-retall)
    (local-set-key [f5] 'idlwave-shell-break-here)
    (local-set-key [f6] 'idlwave-shell-clear-current-bp)
    (local-set-key [f7] 'idlwave-shell-cont)
    (local-set-key [f8] 'idlwave-shell-clear-all-bp)))

3.3 Lesson III: User and Library Catalogs

We have already used the routine info display in the first part of this tutorial. This was the invoked using C-c ?, and displays information about the IDL routine near the cursor position. Wouldn’t it be nice to have the same kind of information available for your own routines and for the huge amount of code in major libraries like JHUAPL or the IDL-Astro library? In many cases, you may already have this information. Files named .idlwave_catalog in library directories contain scanned information on the routines in that directory; many popular libraries ship with these “library catalogs” pre-scanned. Users can scan their own routines in one of two ways: either using the supplied tool to scan directories and build their own .idlwave_catalog files, or using the built-in method to create a single “user catalog”, which we’ll show here. See Catalogs, for more information on choosing which method to use.

To build a user catalog, select Routine Info/Select Catalog Directories from the IDLWAVE entry in the menu bar. If necessary, start the shell first with C-c C-s (see Starting the Shell). IDLWAVE will find out about the IDL !PATH variable and offer a list of directories on the path. Simply select them all (or whichever you want; directories with existing library catalogs will not be selected by default) and click on the ‘Scan&Save’ button. Then go for a cup of coffee while IDLWAVE collects information for each and every IDL routine on your search path. All this information is written to the file ~/.emacs.d/idlwave/idlusercat.el and will from now on automatically load whenever you use IDLWAVE. You may find it necessary to rebuild the catalog on occasion as your local libraries change, or build a library catalog for those directories instead. Invoke routine info (C-c ?) or completion (M-TAB) on any routine or partial routine name you know to be located in the library. E.g., if you have scanned the IDL-Astro library:

    a=readfM-TAB

expands to “readfits(”. Then try

    a=readfits(C-c ?

and you get:

Usage:    Result = READFITS(filename, header, heap)
...

I hope you made it until here. Now you are set to work with IDLWAVE. On the way you will want to change other things, and to learn more about the possibilities not discussed in this short tutorial. Read the manual, look at the documentation strings of interesting variables (with C-h v idlwave<-variable-name> RET) and ask the remaining questions on the newsgroup comp.lang.idl-pvwave.

4.1 Code Formatting

The IDL language, with its early roots in FORTRAN, modern implementation in C, and liberal borrowing of features of many vector and other languages along its 25+ year history, has inherited an unusual mix of syntax elements. Left to his or her own devices, a novice IDL programmer will often conjure code which is very difficult to read and impossible to adapt. Much can be gleaned from studying available IDL code libraries for coding style pointers, but, due to the variety of IDL syntax elements, replicating this style can be challenging at best. Luckily, IDLWAVE understands the structure of IDL code very well, and takes care of almost all formatting issues for you. After configuring it to match your coding standards, you can rely on it to help keep your code neat and organized.

• Code Indentation
• Continued Statement Indentation
• Comment Indentation
• Continuation Lines and Filling
• Syntax Highlighting
• Octals and Highlighting

function foo, a, b,  $
              c, d
  bar =  sin( a + b + $
              c + d)
end

function thisfunctionnameisverylongsoitwillleavelittleroom, a, b, $
                                                            c, d

;=================================
; x - an array containing
;     lots of interesting numbers.
;
; y - another variable where
;     a hanging paragraph is used
;     to describe it.
;=================================

(add-hook 'idlwave-mode-hook 'turn-on-font-lock)

  string("305B) + $ ;" <--- for font-lock
   ' is an Angstrom.'

   string('305'OB) + ' is an Angstrom.'

4.2 Routine Info

IDL comes bundled with more than one thousand procedures, functions and object methods, and large libraries typically contain hundreds or even thousands more (each with a few to tens of keywords and arguments). This large command set can make it difficult to remember the calling sequence and keywords for the routines you use, but IDLWAVE can help. It builds up routine information from a wide variety of sources; IDLWAVE in fact knows far more about the ‘.pro’ routines on your system than IDL itself! It maintains a list of all built-in routines, with calling sequences and keywords². It also scans Emacs buffers for routine definitions, queries the IDLWAVE-Shell for information about routines currently compiled there, and automatically locates library and user-created catalogs. This information is updated automatically, and so should usually be current. To force a global update and refresh the routine information, use C-c C-i (idlwave-update-routine-info).

To display the information about a routine, press C-c ?, which calls the command idlwave-routine-info. When the current cursor position is on the name or in the argument list of a procedure or function, information will be displayed about the routine. For example, consider the indicated cursor positions in the following line:

plot,x,alog(x+5*sin(x) + 2),
  |  |   |   |   |  |  |    |
  1  2   3   4   5  6  7    8

On positions 1,2 and 8, information about the ‘plot’ procedure will be shown. On positions 3,4, and 7, the ‘alog’ function will be described, while positions 5 and 6 will investigate the ‘sin’ function.

When you ask for routine information about an object method, and the method exists in several classes, IDLWAVE queries for the class of the object, unless the class is already known through a text property on the ‘->’ operator (see Object Method Completion and Class Ambiguity), or by having been explicitly included in the call (e.g., a->myclass::Foo).

The description displayed contains the calling sequence, the list of keywords and the source location of this routine. It looks like this:

Usage:    XMANAGER, NAME, ID
Keywords: BACKGROUND CATCH CLEANUP EVENT_HANDLER GROUP_LEADER
          JUST_REG MODAL NO_BLOCK
Source:   SystemLib   [LCSB] /soft1/idl53/lib/xmanager.pro

If a definition of this routine exists in several files accessible to IDLWAVE, several ‘Source’ lines will point to the different files. This may indicate that your routine is shadowing a system library routine, which may or may not be what you want (see Load-Path Shadows). The information about the calling sequence and keywords is derived from the first source listed. Library routines are available only if you have scanned your local IDL directories or are using pre-scanned libraries (see Catalogs). The source entry consists of a source category, a set of flags and the path to the source file. The following default categories exist:

Any routines discovered in library catalogs (see Library Catalogs), will display the category assigned during creation, e.g., ‘NasaLib’. For routines not discovered in this way, you can create additional categories based on the routine’s filename using the variable idlwave-special-lib-alist.

The flags [LCSB] indicate the source of the information IDLWAVE has regarding the file: from a library catalog ([L---]), from a user catalog ([-C--], from the IDL Shell ([--S-]) or from an Emacs buffer ([---B]). Combinations are possible (a compiled library routine visited in a buffer might read [L-SB]). If a file contains multiple definitions of the same routine, the file name will be prefixed with ‘(Nx)’ where ‘N’ is the number of definitions.

Some of the text in the *Help* routine info buffer will be active (it is highlighted when the mouse moves over it). Typically, clicking with the right mouse button invokes online help lookup, and clicking with the middle mouse button inserts keywords or visits files:

User Option: idlwave-resize-routine-help-window (t) ¶

Non-nil means resize the Routine-info *Help* window to fit the content.

User Option: idlwave-special-lib-alist ¶

Alist of regular expressions matching special library directories.

User Option: idlwave-rinfo-max-source-lines (5) ¶

Maximum number of source files displayed in the Routine Info window.

4.3 Online Help

For IDL system routines, extensive documentation is supplied with IDL. IDLWAVE can access the HTML version of this documentation very quickly and accurately, based on the local context. This can be much faster than using the IDL online help application, because IDLWAVE usually gets you to the right place in the documentation directly—e.g., a specific keyword of a routine—without any additional browsing and scrolling.

For this online help to work, an HTML version of the IDL documentation is required. Beginning with IDL 6.2, HTML documentation is distributed directly with IDL, along with an XML-based catalog of routine information. By default, IDLWAVE automatically attempts to convert this XML catalog into a format Emacs can more easily understand, and caches this information in your idlwave_config_directory (~/.emacs.d/idlwave/, by default). It also re-scans the XML catalog if it is newer than the current cached version. You can force rescan with the menu entry IDLWAVE->Routine Info->Rescan XML Help Catalog.

Before IDL 6.2, the HTML help was not distributed with IDL, and was not part of the standalone IDLWAVE distribution, but had to be downloaded separately. This is no longer necessary: all help and routine information is supplied with IDL versions 6.2 and later.

There are a variety of options for displaying the HTML help: see below. Help for routines without HTML documentation is also available, by using the routine documentation header and/or routine source.

In any IDL program (or, as with most IDLWAVE commands, in the IDL Shell), press M-? (idlwave-context-help), or click with S-mouse-3 to access context sensitive online help. The following locations are recognized context for help:

Note that the OBJ_NEW function is special in that the help displayed depends on the cursor position. If the cursor is on the ‘OBJ_NEW’, this function is described. If it is on the class name inside the quotes, the documentation for the class is pulled up. If the cursor is after the class name, anywhere in the argument list, the documentation for the corresponding Init method and its keywords is targeted.

Apart from an IDLWAVE buffer or shell, there are two more places from which online help can be accessed.

• Online help for routines and keywords can be accessed through the Routine Info display. Click with mouse-3 on an item to see the corresponding help (see Routine Info).
• When using completion and Emacs pops up a *Completions* buffer with possible completions, clicking with mouse-3 on a completion item invokes help on that item (see Completion). Items for which help is available in the online system documentation (vs. just the program source itself) will be emphasized (e.g., colored blue).

In both cases, a blue face indicates that the item is documented in the IDL manual, but an attempt will be made to visit non-blue items directly in the originating source file.

• Help with HTML Documentation
• Help with Source

4.4 Completion

IDLWAVE offers completion for class names, routine names, keywords, system variables, system variable tags, class structure tags, regular structure tags and file names. As in many programming modes, completion is bound to M-TAB (or simply TAB in the IDLWAVE Shell; see Using the Shell). Completion uses exactly the same internal information as routine info, so when necessary (rarely) it can be updated with C-c C-i (idlwave-update-routine-info).

The completion function is context sensitive and figures out what to complete based on the location of the point. Here are example lines and what M-TAB would try to complete when the cursor is on the position marked with a ‘_’:

plo_                    Procedure
x = a_                  Function
plot,xra_               Keyword of plot procedure
plot,x,y,/x_            Keyword of plot procedure
plot,min(_              Keyword of min function
obj -> a_               Object method (procedure)
a[2,3] = obj -> a_      Object method (function)
x = obj_new('IDL_       Class name
x = obj_new('MyCl',a_   Keyword to Init method in class MyCl
pro A_                  Class name
pro _                   Fill in Class:: of first method in this file
!v_                     System variable
!version.t_             Structure tag of system variable
self.g_                 Class structure tag in methods
state.w_                Structure tag, if tag completion enabled
name = 'a_              File name (default inside quotes)

The only place where completion is ambiguous is procedure/function keywords versus functions. After ‘plot,x,_’, IDLWAVE will always assume a keyword to ‘plot’. However, a function is also a possible completion here. You can force completion of a function name at such a location by using a prefix arg: C-u M-TAB.

Giving two prefix arguments (C-u C-u M-TAB) prompts for a regular expression to search among the commands to be completed. As an example, completing a blank line in this way will allow you to search for a procedure matching a regexp.

If the list of completions is too long to fit in the *Completions* window, the window can be scrolled by pressing M-TAB repeatedly. Online help (if installed) for each possible completion is available by clicking with mouse-3 on the item. Items for which system online help (from the IDL manual) is available will be emphasized (e.g., colored blue). For other items, the corresponding source code or DocLib header will be used as the help text.

Completion is not a blocking operation; you are free to continue editing, enter commands, or simply ignore the *Completions* buffer during a completion operation. If, however, the most recent command was a completion, C-g will remove the buffer and restore the window configuration. You can also remove the buffer at any time with no negative consequences.

User Option: idlwave-keyword-completion-adds-equal (t) ¶

Non-nil means completion automatically adds ‘=’ after completed keywords.

User Option: idlwave-function-completion-adds-paren (t) ¶

Non-nil means completion automatically adds ‘(’ after completed function. A value of 2 means also add the closing parenthesis and position the cursor between the two.

User Option: idlwave-completion-restore-window-configuration (t) ¶

Non-nil means restore window configuration after successful completion.

User Option: idlwave-highlight-help-links-in-completion (t) ¶

Non-nil means highlight completions for which system help is available.

• Case of Completed Words
• Object Method Completion and Class Ambiguity
• Object Method Completion in the Shell
• Class and Keyword Inheritance
• Structure Tag Completion

(with-eval-after-load 'idlwave
  (require 'idlw-complete-structtag))

IDL> st.[Tab]

4.5 Routine Source

In addition to clicking on a Source: line in the routine info window, there is another way to quickly visit the source file of a routine. The command C-c C-v (idlwave-find-module) asks for a module name, offering the same default as idlwave-routine-info would have used, taken from nearby buffer contents. In the minibuffer, specify a complete routine name (including any class part). IDLWAVE will display the source file in another window, positioned at the routine in question. You can also limit this to a routine in the current buffer only, with completion, and a context-sensitive default, by using a single prefix (C-u C-c C-v) or the convenience binding C-c C-t.

Since getting the source of a routine into a buffer is so easy with IDLWAVE, too many buffers visiting different IDL source files are sometimes created. The special command C-c C-k (idlwave-kill-autoloaded-buffers) can be used to easily remove these buffers.

4.6 Resolving Routines

The key sequence C-c = calls the command idlwave-resolve and sends the line ‘RESOLVE_ROUTINE, 'routine_name'’ to IDL in order to resolve (compile) it. The default routine to be resolved is taken from context, but you get a chance to edit it. Usually this is not necessary, since IDL automatically discovers routines on its path.

idlwave-resolve is one way to get a library module within reach of IDLWAVE’s routine info collecting functions. A better way is to keep routine information available in catalogs (see Catalogs). Routine info on modules will then be available without the need to compile the modules first, and even without a running shell.

See Sources of Routine Info, for more information on the ways IDLWAVE collects data about routines, and how to update this information.

4.7 Code Templates

IDLWAVE can insert IDL code templates into the buffer. For a few templates, this is done with direct key bindings:

All code templates are also available as abbreviations (see Abbreviations).

4.8 Abbreviations

Special abbreviations exist to enable rapid entry of commonly used commands. Emacs abbreviations are expanded by typing text into the buffer and pressing SPC or RET. The special abbreviations used to insert code templates all start with a ‘\’ (the backslash), or, optionally, any other character set in idlwave-abbrev-start-char. IDLWAVE ensures that abbreviations are only expanded where they should be (i.e., not in a string or comment), and permits the point to be moved after an abbreviation expansion: very useful for positioning the mark inside of parentheses, etc.

Special abbreviations are pre-defined for code templates and other useful items. To visit the full list of abbreviations, use M-x idlwave-list-abbrevs.

Template abbreviations:

String abbreviations:

You can easily add your own abbreviations or override existing abbrevs with define-abbrev in your mode hook, using the convenience function idlwave-define-abbrev:

(add-hook 'idlwave-mode-hook
          (lambda ()
            (idlwave-define-abbrev "wb" "widget_base()"
                     (idlwave-keyword-abbrev 1))
            (idlwave-define-abbrev "ine" "IF N_Elements() EQ 0 THEN"
                     (idlwave-keyword-abbrev 11))))

Notice how the abbreviation (here wb) and its expansion (widget_base()) are given as arguments, and the single argument to idlwave-keyword-abbrev (here 1) specifies how far back to move the point upon expansion (in this example, to put it between the parentheses).

The abbreviations are expanded in upper or lower case, depending upon the variables idlwave-abbrev-change-case and, for reserved word templates, idlwave-reserved-word-upcase (see Case Changes).

User Option: idlwave-abbrev-start-char ("\") ¶

A single character string used to start abbreviations in abbrev mode. Beware of common characters which might naturally occur in sequence with abbreviation strings.

User Option: idlwave-abbrev-move (t) ¶

Non-nil means the abbrev hook can move point, e.g., to end up between the parentheses of a function call.

4.9 Actions

Actions are special formatting commands which are executed automatically while you write code in order to check the structure of the program or to enforce coding standards. Most actions which have been implemented in IDLWAVE are turned off by default, assuming that the average user wants her code the way she writes it. But if you are a lazy typist and want your code to adhere to certain standards, actions can be helpful.

Actions can be applied in three ways:

• Some actions are applied directly while typing. For example, pressing ‘=’ can run a check to make sure that this operator is surrounded by spaces and insert these spaces if necessary. Pressing SPC after a reserved word can call a command to change the word to upper case.
• When a line is re-indented with TAB, actions can be applied to the entire line. To enable this, the variable idlwave-do-actions must be non-nil.
• Actions can also be applied to a larger piece of code, e.g., to convert foreign code to your own style. To do this, mark the relevant part of the code and execute M-x expand-region-abbrevs. Useful marking commands are C-x h (the entire file) or C-M-h (the current subprogram). See Code Indentation, for information how to adjust the indentation of the code.

User Option: idlwave-do-actions (nil) ¶

Non-nil means performs actions when indenting. Individual action settings are described below and set separately.

• Block Boundary Check
• Padding Operators
• Case Changes

(add-hook 'idlwave-mode-hook
  (lambda ()
     (setq idlwave-surround-by-blank t)  ; Turn this type of actions on
     (idlwave-action-and-binding "*" '(idlwave-surround 1 1))
     (idlwave-action-and-binding "+" '(idlwave-surround 1 1))))

(add-hook 'idlwave-mode-hook
  (lambda ()
     ;;  Capitalize system vars
     (idlwave-action-and-binding idlwave-sysvar '(capitalize-word 1) t)
     ;;  Capitalize procedure name
     (idlwave-action-and-binding "\\<\\(pro\\|function\\)\\>[ \t]*\\<"
                                 '(capitalize-word 1) t)
     ;;  Capitalize common block name
     (idlwave-action-and-binding "\\<common\\>[ \t]+\\<"
                                 '(capitalize-word 1) t)))

4.10 Documentation Header

The command C-c C-h inserts a standard routine header into the buffer, with the usual fields for documentation (a different header can be specified with idlwave-file-header). One of the keywords is ‘MODIFICATION HISTORY’ under which the changes to a routine can be recorded. The command C-c C-m jumps to the ‘MODIFICATION HISTORY’ of the current routine or file and inserts the user name with a timestamp.

User Option: idlwave-file-header ¶

The doc-header template or a path to a file containing it.

User Option: idlwave-header-to-beginning-of-file (nil) ¶

Non-nil means the documentation header will always be at start of file.

User Option: idlwave-timestamp-hook ¶

The hook function used to update the timestamp of a function.

User Option: idlwave-doc-modifications-keyword ¶

The modifications keyword to use with the log documentation commands.

User Option: idlwave-doclib-start ¶

Regexp matching the start of a document library header.

User Option: idlwave-doclib-end ¶

Regexp matching the start of a document library header.

4.11 Motion Commands

IDLWAVE supports Imenu, a package which make it easy to jump to the definitions of functions and procedures in the current file with a pop-up selection. To bind Imenu to a mouse-press, use in your .emacs:

(define-key global-map [S-down-mouse-3] 'imenu)

In addition, Speedbar support allows convenient navigation of a source tree of IDL routine files, quickly stepping to routine definitions. See Tools->Display Speedbar.

Several commands allow you to move quickly through the structure of an IDL program:

4.12 Miscellaneous Options

User Option: idlwave-help-application ¶

The external application providing reference help for programming.

User Option: idlwave-startup-message (t) ¶

Non-nil means display a startup message when idlwave-mode’ is first called.

User Option: idlwave-mode-hook ¶

Normal hook. Executed when a buffer is put into idlwave-mode.

5.1 Starting the Shell

The IDLWAVE shell can be started with the command M-x idlwave-shell. In idlwave-mode the function is bound to C-c C-s. It creates a buffer *idl* which is used to interact with the shell. If the shell is already running, C-c C-s will simply switch to the shell buffer. The command C-c C-l (idlwave-shell-recenter-shell-window) displays the shell window without selecting it. The shell can also be started automatically when another command tries to send a command to it. To enable auto start, set the variable idlwave-shell-automatic-start to t.

In order to create a separate frame for the IDLWAVE shell buffer, call idlwave-shell with a prefix argument: C-u C-c C-s or C-u C-c C-l. If you always want a dedicated frame for the shell window, configure the variable idlwave-shell-use-dedicated-frame.

To launch a quick IDLWAVE shell directly from a shell prompt without an IDLWAVE buffer (e.g., as a replacement for running inside an xterm), define a system alias with the following content:

emacs -geometry 80x32 -eval "(idlwave-shell 'quick)"

Replace the ‘-geometry 80x32’ option with ‘-nw’ if you prefer the Emacs process to run directly inside the terminal window.

To use IDLWAVE with ENVI or other custom packages which change the ‘IDL> ’ prompt, you must change the idlwave-shell-prompt-pattern, which defaults to ‘"^ ?IDL> "’. Normally, you can just replace the ‘IDL’ in this expression with the prompt you see. A suitable pattern which matches the prompt for both ENVI and IDL simultaneously is ‘"^ ?\\(ENVI\\|IDL\\)> "’.

User Option: idlwave-shell-explicit-file-name (idl) ¶

This is the command to run IDL.

User Option: idlwave-shell-command-line-options ¶

A list of command line options for calling the IDL program.

User Option: idlwave-shell-prompt-pattern ¶

Regexp to match IDL prompt at beginning of a line.

User Option: idlwave-shell-process-name ¶

Name to be associated with the IDL process.

User Option: idlwave-shell-automatic-start (nil) ¶

Non-nil means attempt to invoke idlwave-shell if not already running.

User Option: idlwave-shell-initial-commands ¶

Initial commands, separated by newlines, to send to IDL.

User Option: idlwave-shell-save-command-history (t) ¶

Non-nil means preserve command history between sessions.

User Option: idlwave-shell-command-history-file (~/.emacs.d/idlwave/.idlwhist) ¶

The file in which the command history of the idlwave shell is saved. Unless it’s an absolute path, it goes in idlwave-config-directory.

User Option: idlwave-shell-use-dedicated-frame (nil) ¶

Non-nil means IDLWAVE should use a special frame to display the shell buffer.

User Option: idlwave-shell-use-dedicated-window (nil) ¶

Non-nil means use a dedicated window for the shell, taking care not it replace it with other buffers.

User Option: idlwave-shell-frame-parameters ¶

The frame parameters for a dedicated idlwave-shell frame.

User Option: idlwave-shell-raise-frame (t) ¶

Non-nil means idlwave-shell raises the frame showing the shell window.

User Option: idlwave-shell-temp-pro-prefix ¶

The prefix for temporary IDL files used when compiling regions.

User Option: idlwave-shell-mode-hook ¶

Hook for customizing idlwave-shell-mode.

5.2 Using the Shell

The IDLWAVE shell works in the same fashion as other shell modes in Emacs. It provides command history, command line editing and job control. The UP and DOWN arrows cycle through the input history just like in an X terminal³. The history is preserved between emacs and IDL sessions. Here is a list of commonly used commands:

In addition to these standard comint commands, idlwave-shell-mode provides many of the same commands which simplify writing IDL code available in IDLWAVE buffers. This includes abbreviations, online help, and completion. See Routine Info and Online Help and Completion for more information on these commands.

User Option: idlwave-shell-arrows-do-history (t) ¶

Non-nil means UP and DOWN arrows move through command history like xterm.

User Option: idlwave-shell-comint-settings ¶

Alist of special settings for the comint variables in the IDLWAVE Shell.

User Option: idlwave-shell-file-name-chars ¶

The characters allowed in file names, as a string. Used for file name completion.

User Option: idlwave-shell-graphics-window-size ¶

Size of IDL graphics windows popped up by special IDLWAVE command.

IDLWAVE works in line input mode: You compose a full command line, using all the power Emacs gives you to do this. When you press RET, the whole line is sent to IDL. Sometimes it is necessary to send single characters (without a newline), for example when an IDL program is waiting for single character input with the GET_KBRD function. You can send a single character to IDL with the command C-c C-x (idlwave-shell-send-char). When you press C-c C-y (idlwave-shell-char-mode-loop), IDLWAVE runs a blocking loop which accepts characters and immediately sends them to IDL. The loop can be exited with C-g. It terminates also automatically when the current IDL command is finished. Check the documentation of the two variables described below for a way to make IDL programs trigger automatic switches of the input mode.

User Option: idlwave-shell-use-input-mode-magic (nil) ¶

Non-nil means IDLWAVE should check for input mode spells in output.

User Option: idlwave-shell-input-mode-spells ¶

The three regular expressions which match the magic spells for input modes.

5.3 Commands Sent to the Shell

The IDLWAVE buffers and shell interact very closely. In addition to the normal commands you enter at the IDL> prompt, many other special commands are sent to the shell, sometimes as a direct result of invoking a key command, menu item, or toolbar button, but also automatically, as part of the normal flow of information updates between the buffer and shell.

The commands sent include breakpoint, .step and other debug commands (see Debugging IDL Programs), .run and other compilation statements (see Compiling Programs), examination commands like print and help (see Examining Variables), and other special purpose commands designed to keep information on the running shell current.

By default, much of this background shell input and output is hidden from the user, but this is configurable. The custom variable idlwave-abbrev-show-commands allows you to configure which commands sent to the shell are shown there. For a related customization for separating the output of examine commands, see Examining Variables.

User Option: idlwave-shell-show-commands ('(run misc breakpoint)) ¶

A list of command types to echo in the shell when sent. Possible values are run for .run, .compile and other run commands, misc for lesser used commands like window, retall,close, etc., breakpoint for breakpoint setting and clearing commands, and debug for other debug, stepping, and continue commands. In addition, if the variable is set to the single symbol 'everything, all the copious shell input is displayed (which is probably only useful for debugging purposes). N.B. For hidden commands which produce output by side-effect, that output remains hidden (e.g., stepping through a print command). As a special case, any error message in the output will be displayed (e.g., stepping to an error).

5.4 Debugging IDL Programs

Programs can be compiled, run, and debugged directly from the source buffer in Emacs, walking through arbitrarily deeply nested code, printing expressions and skipping up and down the calling stack along the way. IDLWAVE makes compiling and debugging IDL programs far less cumbersome by providing a full-featured, key/menu/toolbar-driven interface to commands like breakpoint, .step, .run, etc. It can even perform complex debug operations not natively supported by IDL (like continuing to the line at the cursor).

The IDLWAVE shell installs key bindings both in the shell buffer and in all IDL code buffers of the current Emacs session, so debug commands work in both places (in the shell, commands operate on the last file compiled). On Emacs versions which support it, a debugging toolbar is also installed. The toolbar display can be toggled with C-c C-d C-t (idlwave-shell-toggle-toolbar).

User Option: idlwave-shell-use-toolbar (t) ¶

Non-nil means use the debugging toolbar in all IDL related buffers.

• A Tale of Two Modes
• Debug Key Bindings
• Breakpoints and Stepping
• Compiling Programs
• Walking the Calling Stack
• Electric Debug Mode

(setq idlwave-shell-debug-modifiers '(control shift))

5.5 Examining Variables

Do you find yourself repeatedly typing, e.g., print,n_elements(x), and similar statements to remind yourself of the type/size/structure/value/etc. of variables and expressions in your code or at the command line? IDLWAVE has a suite of special commands to automate these types of variable or expression examinations. They work by sending statements to the shell formatted to include the indicated expression, and can be accessed in several ways.

These examine commands can be used in the shell or buffer at any time (as long as the shell is running), and are very useful when execution is stopped in a buffer due to a triggered breakpoint or error, or while composing a long command in the IDLWAVE shell. In the latter case, the command is sent to the shell and its output is visible, but point remains unmoved in the command being composed: you can inspect the constituents of a command you’re building without interrupting the process of building it! You can even print arbitrary expressions from older input or output further up in the shell window; any expression, variable, number, or function you see can be examined.

If the variable idlwave-shell-separate-examine-output is non-nil (the default), all examine output will be sent to a special *Examine* buffer, rather than the shell. The output of prior examine commands is saved in this buffer. In this buffer c clears the contents, and q hides the buffer.

The two most basic examine commands are bound to C-c C-d C-p, to print the expression at point, and C-c C-d ?, to invoke help on this expression⁵. The expression at point is either an array expression or a function call, or the contents of a pair of parentheses. The chosen expression is highlighted, and simultaneously the resulting output is highlighted in the shell or separate output buffer. Calling the above commands with a prefix argument will use the current region as expression instead of using the one at point. which can be useful for examining complicated, multi-line expressions. Two prefix arguments (C-u C-u C-c C-d C-p) will prompt for an expression to print directly. By default, when invoking print, only an initial portion of long arrays will be printed, up to idlwave-shell-max-print-length.

For added speed and convenience, there are mouse bindings which allow you to click on expressions and examine their values. Use S-mouse-2 to print an expression and C-M-mouse-2 to invoke help (i.e., you need to hold down META and CONTROL while clicking with the middle mouse button). If you simply click, the nearest expression will be selected in the same manner as described above. You can also drag the mouse in order to highlight exactly the specific expression or sub-expression you want to examine. For custom expression examination, and the powerful customizable pop-up examine selection, See Custom Expression Examination.

The same variable inspection commands work both in the IDL Shell and IDLWAVE buffers, and even for variables at higher levels of the calling stack. For instance, if you’re stopped at a breakpoint in a routine, you can examine the values of variables and expressions inside its calling routine, and so on, all the way up through the calling stack. Simply step up the stack, and print variables as you see them (see Walking the Calling Stack, for information on stepping back through the calling stack). The following restrictions apply for all levels except the current:

• Array expressions must use the ‘[ ]’ index delimiters. Identifiers with a ‘( )’ will be interpreted as function calls.
• N.B.: printing values of expressions on higher levels of the calling stack uses the unsupported IDL routine ROUTINE_NAMES, which may or may not be available in future versions of IDL. Caveat Examinor.

User Option: idlwave-shell-expression-face ¶

The face for idlwave-shell-expression-overlay. Allows you to choose the font, color and other properties for the expression printed by IDL.

User Option: idlwave-shell-output-face ¶

The face for idlwave-shell-output-overlay. Allows to choose the font, color and other properties for the most recent output of IDL when examining an expression."

User Option: idlwave-shell-separate-examine-output (t) ¶

If non-nil, re-direct the output of examine commands to a special *Examine* buffer, instead of in the shell itself.

User Option: idlwave-shell-max-print-length (200) ¶

The maximum number of leading array entries to print, when examining array expressions.

5.6 Custom Expression Examination

The variety of possible variable and expression examination commands is endless (just look, for instance, at the keyword list to widget_info()). Rather than attempt to include them all, IDLWAVE provides two easy methods to customize your own commands, with a special mouse examine command, and two macros for generating your own examine key and mouse bindings.

The most powerful and flexible mouse examine command of all is available on C-S-mouse-2. Just as for all the other mouse examine commands, it permits click or drag expression selection, but instead of sending hard-coded commands to the shell, it pops-up a customizable selection list of examine functions to choose among, configured with the idlwave-shell-examine-alist variable⁶. This variable is a list of key-value pairs (an alist in Emacs parlance), where the key gives a name to be shown for the examine command, and the value is the command strings itself, in which the text ___ (three underscores) will be replaced by the selected expression before being sent to the shell. An example might be key Structure Help with value help,___,/STRUCTURE. In that case, you’d be prompted with Structure Help, which might send something like help,var,/STRUCTURE to the shell for output. idlwave-shell-examine-alist comes configured by default with a large list of examine commands, but you can easily customize it to add your own.

In addition to configuring the functions available to the pop-up mouse command, you can easily create your own customized bindings to inspect expressions using the two convenience macros idlwave-shell-examine and idlwave-shell-mouse-examine. These create keyboard or mouse-based custom inspections of variables, sharing all the same properties of the built-in examine commands. Both functions take a single string argument sharing the syntax of the idlwave-shell-examine-alist values, e.g.:

(add-hook 'idlwave-shell-mode-hook
          (lambda ()
            (idlwave-shell-define-key-both [s-down-mouse-2]
                                 (idlwave-shell-mouse-examine
                                  "print, size(___,/DIMENSIONS)"))
            (idlwave-shell-define-key-both [f9] (idlwave-shell-examine
                                       "print, size(___,/DIMENSIONS)"))
            (idlwave-shell-define-key-both [f10] (idlwave-shell-examine
                                        "print,size(___,/TNAME)"))
            (idlwave-shell-define-key-both [f11] (idlwave-shell-examine
                                        "help,___,/STRUCTURE"))))

Now pressing f9, or middle-mouse dragging with the SUPER key depressed, will print the dimensions of the nearby or highlighted expression. Pressing f10 will give the type string, and f11 will show the contents of a nearby structure. As you can see, the possibilities are only marginally finite.

User Option: idlwave-shell-examine-alist ¶

An alist of examine commands in which the keys name the command and are displayed in the selection pop-up, and the values are custom IDL examine command strings to send, after all instances of ___ (three underscores) are replaced by the indicated expression.