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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 variable1. 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]
                                       "print, size(___,/DIMENSIONS)"))
                 (idlwave-shell-define-key-both [f9] (idlwave-shell-examine
                                            "print, size(___,/DIMENSIONS)"))
                 (idlwave-shell-define-key-both [f10] (idlwave-shell-examine
                 (idlwave-shell-define-key-both [f11] (idlwave-shell-examine

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.


[1] In Electric Debug Mode (see Electric Debug Mode), the key x provides a single-character shortcut interface to the same examine functions for the expression at point or marked by the region.