On Oct 2, 2010, at 7:20 AM, Ken Thomases wrote:
>> Sorry to be obtuse, but it may be that I am overlooking something.
>> Presently, we have calls such as
>>
>> n = PyNumber_Float(obj)
>> s = PyString_AsString(obj)
>>
>> I understand that I would need to generate #defines for all those names,
>> such as PyNumber_Float to map them to some table. I would have to initialize
>> that table in a big for loop that goes through another table containing the
>> name of each function (e.g. "PyNumber_Float". The loop then looks each name
>> up with dlsym and initializes the table.
>>
>> Or can this be done more elegantly?
> Declare function pointers:
>
> typeof(PyNumber_Float) *pPyNumber_Float;
> typeof(PyString_AsString) * pPyString_AsString;
>
> This can be table-ized with a macro:
>
> #define DOFUNC(f) typeof(f) *p##f
> DOFUNC(PyNumber_Float);
> DOFUNC(PyString_AsString);
> // ...
> #undef DOFUNC
>
>
> During initialization, dynamically load the Python framework with dlopen().
> Then, load the function pointers by looking up the symbols:
>
> pPyNumber_Float = dlsym(handle, "PyNumber_Float");
> pPyString_AsString = dlsym(handle, "PyString_AsString");
>
> This can be table-ized with a macro:
>
> #define DOFUNC(f) do { if (!(p##f = dlsym(handle, #f))) { \
> fprintf(stderr, "Failed to load %s\n", #f); \
> goto bail; \
> } while (0)
> DOFUNC(PyNumber_Float);
> DOFUNC(PyString_AsString);
> // ...
> #undef DOFUNC
>
>
> Notice that the table within the definitions of DOFUNC is identical in both
> cases. So, you can extract it to a separate file and #include it between the
> DOFUNC #define and #undef:
>
> #define DOFUNC(f) /* whatever */
> #include "PythonFunctionDoFuncs.h"
> #undef DOFUNC
>
> That way there's just the one table for both purposes.
>
>
> Then, you have two choices. 1) Throughout your code, call the functions with
> the function pointers. This basically entails prepending a "p" to all the
> function names. 2) Use macros to do this for you:
>
> #define PyNumber_Float pPyNumber_Float
> #define PyString_AsString pPyString_AsString
>
> I can't think of a technique to table-ize the above. There may be one that
> I'm forgetting, but I don't think so. Still, that's just two places to touch
> for each Python function you use.
>
> If you want to get fancier, you could have a single file which just lists the
> Python functions you use, one per line. Then, a script would generate both
> the PythonFunctionDoFuncs.h and a PythonFunctionRedefines.h (with the above
> macro definitions) from that list.
#!/usr/bin/env lua
funcs = ""
loaders = "BOOL\tPython_LoadFunctions()\n{\n"
defs = ""
for line in io.lines("PythonFunctions.def") do
funcs = funcs .. string.format("typeof(%s) *p%s\n", line, line)
loaders = loaders .. string.format("if (!(p%s = dlsym(handle,
\"%s\")))\n{\n" ..
"fprintf(stderr, "Failed to load %s\n");\ngoto bail;\n}\n",
line, line, line)
defs = defs .. string.format("#define %s p%s\n", line, line)
end
loaders = loaders .. "return YES;\nbail:\nreturn NO;\n}\n"
io.open("PythonFunctions.h", "w"):write(funcs .. "\n" .. loaders .. "\n" ..
defs)
-- EOF
Disclaimer: Written entirely in Mail and untested. Lua is not installed by
default on Mac OS! Do it in Python instead, which I don't know enough to give
the example in.
Set up an Xcode build rule in your target for files matching the pattern
"PythonFunctions.def" and containing this script, with
$(DERIVED_FILES_DIR)/PythonFunctions.h as the output file. Then #include the
file in your source; Xcode should do the right thing from there.
-- Gwynne
_______________________________________________
Cocoa-dev mailing list (Cocoa-dev@lists.apple.com)
Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com
This email sent to arch...@mail-archive.com
