fish-shell/doc_src/cmds/fish_opt.rst

.. _cmd-fish_opt:

fish_opt - create an option specification for the argparse command
==================================================================

Synopsis
--------

.. synopsis::

    fish_opt [(-slor | --multiple-vals=) OPTNAME]
    fish_opt --help

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

This command provides a way to produce option specifications suitable for use with the :ref:`argparse <cmd-argparse>` command. You can, of course, write the option specifications by hand without using this command. But you might prefer to use this for the clarity it provides.

The following ``argparse`` options are available:

**-s** or **--short**
    Takes a single letter that is used as the short flag in the option being defined. This option is mandatory.

**-l** or **--long**
    Takes a string that is used as the long flag in the option being defined. This option is optional and has no default. If no long flag is defined then only the short flag will be allowed when parsing arguments using the option specification.

**--long-only**
    The option being defined will only allow the long flag name to be used. The short flag name must still be defined (i.e., **--short** must be specified) but it cannot be used when parsing arguments using this option specification.

**-o** or **--optional-val**
    Tthe option being defined can take a value, but it is optional rather than required. If the option is seen more than once when parsing arguments, only the last value seen is saved. This means the resulting flag variable created by ``argparse`` will zero elements if no value was given with the option else it will have exactly one element.

**-r** or **--required-val**
    The option being defined requires a value. If the option is seen more than once when parsing arguments, only the last value seen is saved. This means the resulting flag variable created by ``argparse`` will have exactly one element.

**--multiple-vals**
    The option being defined requires a value each time it is seen. Each instance is stored. This means the resulting flag variable created by ``argparse`` will have one element for each instance of this option in the arguments.

**-h** or **--help**
    Displays help about using this command.

Examples
--------

Define a single option specification for the boolean help flag:


::

    set -l options (fish_opt -s h -l help)
    argparse $options -- $argv


Same as above but with a second flag that requires a value:


::

    set -l options (fish_opt -s h -l help)
    set options $options (fish_opt -s m -l max --required-val)
    argparse $options -- $argv


Same as above but with a third flag that can be given multiple times saving the value of each instance seen and only the long flag name (``--token``) can be used:


::

    set -l options (fish_opt --short=h --long=help)
    set options $options (fish_opt --short=m --long=max --required-val)
    set options $options (fish_opt --short=t --long=token --multiple-vals --long-only)
    argparse $options -- $argv
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 17:05:09 +08:00			`.. _cmd-fish_opt:`

docs: omnibus cleanup Includes harmonizing the display of options and arguments, standardising terminology, using the envvar directive more broadly, adding help options to all commands that support them, simplifying some language, and tidying up multiple formatting issues. string documentation is not changed. 2022-03-12 00:18:41 +08:00			`fish_opt - create an option specification for the argparse command`
			`==================================================================`
Switch command docs from \section to reStructuredText 2018-12-17 09:39:33 +08:00
Migrate the 'synopsis' sections to .rst format 2018-12-18 09:58:24 +08:00			`Synopsis`
			`--------`
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 22:09:46 +08:00
			`.. synopsis::`

docs synopsis: make all placeholder arguments uppercase man(1) uses lowercase placeholders but we usually don't. Additionally, the new synopsis autoformatting only recognizes placeholders if they are uppercase. Use uppercase for all placeholders. 2022-01-17 12:29:49 +08:00			`fish_opt [(-slor \| --multiple-vals=) OPTNAME]`
docs: omnibus cleanup Includes harmonizing the display of options and arguments, standardising terminology, using the envvar directive more broadly, adding help options to all commands that support them, simplifying some language, and tidying up multiple formatting issues. string documentation is not changed. 2022-03-12 00:18:41 +08:00			`fish_opt --help`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
Convert \\subsection sections into rst format 2018-12-19 10:44:30 +08:00			`Description`
Fix command section separator line lengths 2019-01-03 12:10:47 +08:00			`-----------`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: omnibus cleanup Includes harmonizing the display of options and arguments, standardising terminology, using the envvar directive more broadly, adding help options to all commands that support them, simplifying some language, and tidying up multiple formatting issues. string documentation is not changed. 2022-03-12 00:18:41 +08:00			This command provides a way to produce option specifications suitable for use with the :ref:`argparse <cmd-argparse>` command. You can, of course, write the option specifications by hand without using this command. But you might prefer to use this for the clarity it provides.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
Switch backticks to double backticks for rst compatibility 2018-12-20 04:02:45 +08:00			The following ``argparse`` options are available:
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-s or --short`
			`Takes a single letter that is used as the short flag in the option being defined. This option is mandatory.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-l or --long`
			`Takes a string that is used as the long flag in the option being defined. This option is optional and has no default. If no long flag is defined then only the short flag will be allowed when parsing arguments using the option specification.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`--long-only`
			`The option being defined will only allow the long flag name to be used. The short flag name must still be defined (i.e., --short must be specified) but it cannot be used when parsing arguments using this option specification.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-o or --optional-val`
			Tthe option being defined can take a value, but it is optional rather than required. If the option is seen more than once when parsing arguments, only the last value seen is saved. This means the resulting flag variable created by ``argparse`` will zero elements if no value was given with the option else it will have exactly one element.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-r or --required-val`
			The option being defined requires a value. If the option is seen more than once when parsing arguments, only the last value seen is saved. This means the resulting flag variable created by ``argparse`` will have exactly one element.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`--multiple-vals`
			The option being defined requires a value each time it is seen. Each instance is stored. This means the resulting flag variable created by ``argparse`` will have one element for each instance of this option in the arguments.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-h or --help`
			`Displays help about using this command.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
Convert \\subsection sections into rst format 2018-12-19 10:44:30 +08:00			`Examples`
Fix command section separator line lengths 2019-01-03 12:10:47 +08:00			`--------`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: omnibus cleanup Includes harmonizing the display of options and arguments, standardising terminology, using the envvar directive more broadly, adding help options to all commands that support them, simplifying some language, and tidying up multiple formatting issues. string documentation is not changed. 2022-03-12 00:18:41 +08:00			`Define a single option specification for the boolean help flag:`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
Switch \fish sections to rst format 2018-12-19 11:14:04 +08:00

			`::`

			`set -l options (fish_opt -s h -l help)`
			`argparse $options -- $argv`

Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
			`Same as above but with a second flag that requires a value:`

Switch \fish sections to rst format 2018-12-19 11:14:04 +08:00

			`::`

			`set -l options (fish_opt -s h -l help)`
			`set options $options (fish_opt -s m -l max --required-val)`
			`argparse $options -- $argv`

Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
Switch backticks to double backticks for rst compatibility 2018-12-20 04:02:45 +08:00			Same as above but with a third flag that can be given multiple times saving the value of each instance seen and only the long flag name (``--token``) can be used:
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
Switch \fish sections to rst format 2018-12-19 11:14:04 +08:00

			`::`

			`set -l options (fish_opt --short=h --long=help)`
			`set options $options (fish_opt --short=m --long=max --required-val)`
			`set options $options (fish_opt --short=t --long=token --multiple-vals --long-only)`
			`argparse $options -- $argv`