fish-shell/doc_src/cmds/emit.rst

.. _cmd-emit:

emit - emit a generic event
===========================

Synopsis
--------

.. synopsis::

    emit EVENT_NAME [ARGUMENTS ...]

Description
-----------

``emit`` emits, or fires, an event. Events are delivered to, or caught by, special functions called :ref:`event handlers <event>`. The arguments are passed to the event handlers as function arguments.


Example
-------

The following code first defines an event handler for the generic event named 'test_event', and then emits an event of that type.


::

    function event_test --on-event test_event
        echo event test: $argv
    end
    
    emit test_event something


Notes
-----

Note that events are only sent to the current fish process as there is no way to send events from one fish process to another.
docs: Add labels to all commands This allows us to use :ref: references, which don't require hardcoding it as html [ci skip] 2019-03-31 09:05:09 +00:00			`.. _cmd-emit:`

doc: homogenize commands titles 2020-03-31 15:37:38 +00:00			`emit - emit a generic event`
Fix command section separator line lengths 2019-01-03 04:10:47 +00:00			`===========================`
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			`--------`
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docs synopsis: add HTML highlighing and automate manpage markup Recent synopsis changes move from literal code blocks to [RST line blocks]. This does not translate well to HTML: it's not rendered in monospace, so aligment is lost. Additionally, we don't get syntax highlighting in HTML, which adds differences to our code samples which are highlighted. We hard-wrap synopsis lines (like code blocks). To align continuation lines in manpages we need [backslashes in weird places]. Combined with the *, , and `` markup, it's a bit hard to get the alignment right. Fix these by moving synopsis sources back to code blocks and compute HTML syntax highlighting and manpage markup with a custom Sphinx extension. The new Pygments lexer can tokenize a synopsis and assign the various highlighting roles, which closely matches fish's syntax highlighing: - command/keyword (dark blue) - parameter (light blue) - operator like and/or/not/&&/\|\| (cyan) - grammar metacharacter (black) For manpage output, we don't project the fish syntax highlighting but follow the markup convention in GNU's man(1): bold text type exactly as shown. italic text replace with appropriate argument. To make it easy to separate these two automatically, formalize that (italic) placeholders must be uppercase; while all lowercase text is interpreted literally (so rendered bold). This makes manpages more consistent, see string-join(1) and and(1). Implementation notes: Since we want manpage formatting but Sphinx's Pygments highlighing plugin does not support manpage output, add our custom "synopsis" directive. This directive parses differently when manpage output is specified. This means that the HTML and manpage build processes must not share a cache, because the parsed doctrees are cached. Work around this by using separate cache locations for build targets "sphinx-docs" (which creates HTML) and "sphinx-manpages". A better solution would be to only override Sphinx's ManualPageBuilder but that would take a bit more code (ideally we could override ManualPageWriter but Sphinx 4.3.2 doesn't really support that). --- Alternative solution: stick with line blocks but use roles like :command: or :option: (or custom ones). While this would make it possible to produce HTML that is consistent with code blocks (by adding a bit of CSS), the source would look uglier and is harder to maintain. (Let's say we want to add custom formatting to the [\|] metacharacters in HTML. This is much easier with the proposed patch.) --- [RST line blocks]: https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#line-blocks [backslashes in weird places]: https://github.com/fish-shell/fish-shell/pull/8626#discussion_r782837750 2022-01-09 14:09:46 +00:00			`.. synopsis::`

			`emit EVENT_NAME [ARGUMENTS ...]`
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Convert \\subsection sections into rst format 2018-12-19 02:44:30 +00:00			`Description`
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doc: add link to event handlers in emit [ci skip] 2019-10-04 13:03:25 +00:00			``emit`` emits, or fires, an event. Events are delivered to, or caught by, special functions called :ref:`event handlers <event>`. The arguments are passed to the event handlers as function arguments.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-16 21:08:41 +00:00

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			`The following code first defines an event handler for the generic event named 'test_event', and then emits an event of that type.`


Switch \fish sections to rst format 2018-12-19 03:14:04 +00:00
			`::`

			`function event_test --on-event test_event`
			`echo event test: $argv`
			`end`

			`emit test_event something`

Copy doc_src to sphinx_doc_src and add a TOC 2018-12-16 21:08:41 +00:00

Convert \\subsection sections into rst format 2018-12-19 02:44:30 +00:00			`Notes`
Fix command section separator line lengths 2019-01-03 04:10:47 +00:00			`-----`
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			`Note that events are only sent to the current fish process as there is no way to send events from one fish process to another.`