Also instead of defining the library as a function in define-ffi-library I thought it would be better to mark it as a constant since a library is only every opened once. Note that define-ffi-library also had the problem of performing work when expanding the macro as described above.
Finally, I changed the expansion of define-ffi-function based on the expansion of lexical-let. In the previous implementation, a variable which holds the ffi function object returned by ffi--dlsym was using the global obarray symbol table (this holds all the variable and function symbols visible to emacs. This means that describe-variable and the like would show the variable holding the ffi function object when really this is only ever used inside the function returned by define-ffi-function. In this re-implementation, the variables which hold the cif and the ffi function objects are not added to the global obarray and are only visible to the function returned by define-ffi-function.
Call
ffi--prep-cifand thedefiner-functionofffi--struct-union-helperin the calling environment of the macros not during the macro expansion. This is so that compiling programs that usedefine-ffi-function,define-ffi-struct, etc. work. See https://www.gnu.org/software/emacs/manual/html_node/elisp/Wrong-Time.html#Wrong-Time.Also instead of defining the library as a function in
define-ffi-libraryI thought it would be better to mark it as a constant since a library is only every opened once. Note thatdefine-ffi-libraryalso had the problem of performing work when expanding the macro as described above.Finally, I changed the expansion of
define-ffi-functionbased on the expansion oflexical-let. In the previous implementation, a variable which holds theffifunction object returned byffi--dlsymwas using the globalobarraysymbol table (this holds all the variable and function symbols visible to emacs. This means thatdescribe-variableand the like would show the variable holding theffifunction object when really this is only ever used inside the function returned bydefine-ffi-function. In this re-implementation, the variables which hold thecifand theffifunction objects are not added to the globalobarrayand are only visible to the function returned bydefine-ffi-function.