Perform work in macro calling environment #19
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In `define-ffi-function` and `ffi--struct-union-helper` the work to define ffi functions (using `ffi--prep-cif` and `ffi--dlsym`) and types was done in the macro environment. This works fine during runtime, but fails for complied code since the objects would be created at compile time instead of at runtime. By moving the work to the macro's calling environment we avoid this problem.
tarsius
reviewed
Mar 17, 2020
| `(defun ,symbol () | ||
| (or ,library | ||
| (setq ,library (ffi--dlopen ,name)))))) | ||
| `(defconst ,(intern (concat "ffi-" (symbol-name symbol))) |
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You should not also change the name of the symbol in addition to the change described in the commit message.
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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.