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77 lines
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77 lines
3.7 KiB
Plaintext
*nvim_provider.txt* For Nvim. {Nvim}
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NVIM REFERENCE MANUAL by Thiago de Arruda
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Nvim provider infrastructure *nvim-provider*
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First of all, this document is meant to be read by developers interested in
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contributing to the refactoring effort. If you are a normal user or plugin
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developer looking to learn about Nvim |msgpack-rpc| infrastructure for
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implementing plugins in other programming languages, see |remote-plugin|.
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For instructions on how to enable Python plugins, see |nvim-python|. For
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clipboard, see |nvim-clipboard|.
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Instead of doing everything by itself, Nvim aims to simplify its own
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maintenance by delegating as much work as possible to external systems. But
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some Vim components are too tightly coupled and in some cases the refactoring
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work necessary to swap in-house implementations by code that integrates to
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other systems is too great. Nvim provider infrastructure is a facility that
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aims to make this task simpler.
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To understand why the provider infrastructure is useful, let us consider two
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examples of integration with external systems that are implemented in Vim and
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are now decoupled from Nvim core as providers:
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The first example is clipboard integration: in the original Vim source code,
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clipboard functions account for more than 1k lines of C source code (and that
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is just on ui.c), all to perform two tasks that are now accomplished with
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simple shell commands such as xclip or pbcopy/pbpaste.
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The other example is Python scripting support: Vim has three files dedicated to
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embedding the Python interpreter: if_python.c, if_python3.c and if_py_both.h.
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Together these files sum about 9.5k lines of C source code. On Nvim, Python
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scripting is performed by an external host process that is running 2k sloc
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Python program.
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In a perfect world, we would implement Python and clipboard integration in
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pure vimscript and without touching the C code. Unfortunately we can't achieve
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these goals without severely compromising backwards compatibility with Vim.
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That's where providers come to the rescue.
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In essence, this infrastructure is a simple framework that simplifies the task
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of calling vimscript from C code, making it simpler to rewrite C functions that
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interact with external systems in pure vimscript. It is composed of two
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functions in eval.c:
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- eval_call_provider(name, method, arguments): Call a provider(name) method
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with arguments
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- eval_has_provider(name): Checks if a provider is implemented
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What these functions do is simple:
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- eval_call_provider will call the provider#(name)#Call function passing in
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the method and arguments.
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- eval_has_provider will return true if the provider#(name)#Call function is
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implemented, and is called by the "has" vimscript function to check if
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features are available.
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The basic idea is that the provider#(name)#Call function should implement
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integration with an external system, because calling shell commands and
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|msgpack-rpc| clients (Nvim only) is easier to do in vimscript.
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Now, back to the Python example. Instead of modifying vimscript to allow for
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the definition of lowercase functions and commands (for the |:python|,
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|:pyfile|, and |:pydo| commands, and the |pyeval()| function), which would
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break backwards compatibility with Vim, we implemented the
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autoload/provider/python.vim script and the provider#python#Call function
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that is only defined if an external Python host is started successfully.
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That works well with the `has('python')` expression (normally used by Python
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plugins) because if the Python host isn't installed then the plugin will
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"think" it is running in a Vim compiled without |+python| feature.
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==============================================================================
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vim:tw=78:ts=8:noet:ft=help:norl:
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