idlwave: Online Help
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:
Routine names The name of a routine (function, procedure, method).
Keyword A keyword parameter of a routine.
Parameters
System Variables System variables like ‘!DPI’.
System Variable System variables tags like ‘!D.X_SIZE’.
Tags
IDL Statements Statements like ‘PRO’, ‘REPEAT’, ‘COMPILE_OPT’, etc.
IDL Controls Control structures like ‘FOR’, ‘SWITCH’, etc.
Class names A class name in an ‘OBJ_NEW’ call.
Class Init Beyond the class name in an ‘OBJ_NEW’ call.
Keywords
Executive An executive command like ‘.RUN’. Mostly useful in
Command the shell.
Structure Tags Structure tags like ‘state.xsize’
Class Tags Class tags like ‘self.value’.
Default The routine that would be selected for routine info
display.
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 (
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 (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.
Menu
Info Catalog
idlwave: Routine Info
idlwave: The IDLWAVE Major Mode
idlwave: Completion