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Pressing Shift-F1 provides help on the keyword at point,
using a help rule specific to the current mode. Some modes have rules
that consult compiler documentation, man or Info pages, or search on
the web at an API reference site. You can change the rules by setting
Each mode has an associated variable whose name is formed by adding
the mode name to the end of
context-help-rule-. (Characters in
the mode name that aren't valid in EEL identifier names are removed
first; the rest are changed to lowercase.) So HTML mode, for
instance, uses a rule variable named context-help-rule-html.
A mode can define separate rules for Windows and Unix. If a mode
m defines a variable
context-help-rule-m-unix, Epsilon will use it instead of the usual
variable on that platform.
If there's no variable for the current mode, Epsilon uses the rule in
the context-help-default-rule variable.
Instead of, or in addition to, providing a rule variable, a mode can
define an EEL function to force a different rule variable. Epsilon
calls a function named
a mode named modename, if one is defined. That function must
fill in its single
char * parameter with a replacement mode name;
then Epsilon will look up the corresponding variable, as above. C
mode uses this to provide a different help rule for EEL buffers than
for Java or C++ buffers, even though they all use C mode. HTML mode
(or other scripting languages) than it does in plain HTML text.
Each rule variable consists of a rule type, which is a single
punctuation character, followed by a parameter such as a file name or
URL. Here are the rule types:
- looks up the keyword at point in the
index of the Info file specified by its parameter. You can list
multiple comma-separated Info file names, and Epsilon will use the
first one that contains the keyword in its index.
- runs the specified EEL function func.
See below for useful rule functions.
- runs an external program, using the
specified command line. It appends the keyword at point to the end of
the command line. But if the command line contains a
Epsilon instead substitutes the keyword at that position. If the
program file name contains spaces, quote it with
character at the end of the command line makes the command run
asynchronously; use it to run a Windows GUI program. Without
Epsilon will run the program synchronously, collect its output in a
buffer, and display any output it produces.
- runs a web browser on the specified URL. A
* character in the URL substitutes the keyword at point at that
position; otherwise it's added to the end of the URL.
- looks up the keyword at point in a .hlp,
.chm, or .col file. These are Windows help file formats, and this
rule type is only available under Windows.
Here are some functions designed to be used in a context rule. To use
one in a rule, put a
+ before its name in the rule variable.
The context_help_man( ) subroutine runs Epsilon's man
command on the word at point. (The
- characters are
interchangeable in these rules, so you can set a rule to
+context-help-man, for instance, to use this subroutine.)
The context_help_perldoc( ) subroutine runs Epsilon's
perldoc command on the word at point.
Under Windows, you can set a mode to use help provided by Microsoft's
development environment by setting its rule to call the
context_help_windows_compilers( ) subroutine. The subroutine
tries to locate the appropriate compiler help system automatically.
With certain help systems that have multiple help collections, it uses
the mshelp2-collection variable.
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