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Document some restrictions for module functions.

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* doc/lispref/internals.texi (Module Functions): Document some
restrictions for module functions.
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Philipp Stephani 2019-12-26 11:31:51 +01:00
parent e1ce9f3423
commit 21c3020fce
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doc/lispref/internals.texi
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@ -1403,6 +1403,22 @@ the function to that symbol. Note that it is possible to use
@code{fset} instead of @code{defalias}; the differences are described
in @ref{Defining Functions, defalias}.
Module functions including the @code{emacs_module_init} function
(@pxref{module initialization function}) may only interact with Emacs
by calling environment functions from some live @code{emacs_env}
pointer while being called directly or indirectly from Emacs. In
other words, if a module function wants to call Lisp functions or
Emacs primitives, convert @code{emacs_value} objects to and from C
datatypes (@pxref{Module Values}), or interact with Emacs in any other
way, some call from Emacs to @code{emacs_module_init} or to a module
function must be in the callstack. Module function may not interact
with Emacs while garbage collection is running; @pxref{Garbage
Collection}. They may only interact with Emacs from Lisp interpreter
threads (including the main thread) created by Emacs; @pxref{Threads}.
The @kbd{--module-assertions} command-line option can detect some
violations of the above requirements. @xref{Initial Options,,,emacs,
The GNU Emacs Manual}.
Using the module @acronym{API}, it is possible to define more complex
function and data types: interactive functions, inline functions,
macros, etc. However, the resulting C code will be cumbersome and