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:
ROUTINE_NAMES,
which may or may not be available in future versions of IDL. Caveat
Examinor.
The face for idlwave-shell-expression-overlay.
Allows you to choose the font, color and other properties for
the expression printed by IDL.
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."
t) ¶If non-nil, re-direct the output of examine commands to a special
*Examine* buffer, instead of in the shell itself.
The maximum number of leading array entries to print, when examining array expressions.