Gabriel Genellina wrote: > At Friday 6/10/2006 16:14, Thomas Heller wrote: >>For ctypes, the only solution I can think of is to invent a new calling >>convention, which will call setjmp() first internally before calling the >>libpng api function... > > May be reasonable - a non-zero in setjmp would raise a Python > exception. But perhaps a new calling convention is not needed: as you > need a way to indicate *which* argument is the jmp_buf, just a new > argument type would suffice. If you encounter one such thing in the > function.argtypes list, that means a setjmp is needed before calling > the actual function.
The ctypes C code which handles invoking the foreign function call must be responsible for calling setjmp(). You can't call that in Python code - the C stack is manipulated all over the place for each line of Python code executed. You have to both call and set the jmp_buf in the same C code call from Python. Thus my suggestion of configuring a handler function on the foreign function wrapper object alongside the argtypes and restype. If one is defined then ctypes automatically calls setjmp and passes control to that handler function if setjmp returns non-zero. This page: http://www.massey.ac.nz/~mgwalker/misc/create-images.html has some example programs that show setjmp/longjmp in action. Read the whole thing as his first examples aren't correct :) Richard -- http://mail.python.org/mailman/listinfo/python-list
