D 2015-04-03T18:58:04.922
L plugin\smeta\sdata
U mario
W 2672
# Plugin meta spec

Streamtuner2 now uses a proper plugin description scheme. Note that this is completely unrelated to the streamtuner2 or channels API, or how plugins are actually initialized (pkgutil, imp, implib, pluginbase/plugnplay).

Basically the top-level comment block is scanned on initialization. It simply lists a few `key: values` for documentation and technical descriptors. It's basically a subset of YAML embedded in a script comment.

    # api: streamtuner2
    # type: feature
    # title: My Plugin
    # description: Lists all the things
    # version: 1.0
    # category: music
    # config: { name: myconf, value: 1, type: boolean, description: enable foo }
    #
    # And here goes a longer doc/comment.

The key names are case-insensitive of course. A few fields like `title:`, `description:` are required. Theoretically also the `api:` and `type:`. But they're only used for decorative purposes like the `category:` or `version:` field.

More interestingly the `config:` field can be used to describe plugin options. Default values will automatically end up in streamtuners `conf.*` dict, and are presented to users in the config dialog.

   * A `value:` represents the default.
   * The `type: select` can be used for dropdown boxes, with a `select: key=VAl|key2=VAL2..` attribute for options.
   * Other `type:` values are interpreted as strings, except `type: boolean` which becomes a checkbox.
   * A per-option `category:` attribute is ignored at the moment.
   * Params can be optionally quoted as in `value: "Desc, desc, desc." if they contain commas (which otherwise separate option attrs.)

And of course, the `config:` field can list multiple options. Simply make it multi-line (every plugin meta field can be) by indenting wrapped lines.


### Why?

This scheme is designed to be language-agnostic. It originated in PHP way back (see [libconfig](http://milki.include-once.org/genericplugins/)), precisely to avoid common misdesigns.

  * Meta data does not belong *in code*.  
    Because that incurs importing them, even when they may go uninitialized/unused.
  * And it certainly should not reside in externalized ini/json data stores.  
    **Because that's how you get ants!**

The meta description block also can double as packaging format. The `pack:` descriptor is used by [fpm/xpm -s src](http://fossil.include-once.org/xpm/wiki/src). Which avoids manually concocting separated setup.py/.cfg as the current Python packaging eco system does. (This is stuff which can be automated, without requiring meta information to be doubled in-code and dutifully dished up for pip/setuptools).



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