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diff --git a/Mac/Demo/calldll/readme b/Mac/Demo/calldll/readme new file mode 100644 index 0000000..989b34a --- /dev/null +++ b/Mac/Demo/calldll/readme @@ -0,0 +1,57 @@ +Preliminary notes/documentation for the calldll module, version 0.2. +==================================================================== + +Calldll allows you to call random C functions from python without writing any +C code. It is mainly meant to call MacOS toolbox routines for which no Python +wrapper module is available. It is also incomplete, in that only a few argument +types are currently supported. Please let me know which other argument types +you need, and/or whether you have any ideas on a general "escape" allowing people +to pass anything. + +The module works *only* on PowerPC currently. It is distributed complete +with source and project files, so that people willing to look at a CFM68K port +are welcome to do so. A classic 68K implementation is impossible, I think (so +prove me wrong, please:-). + +The module exports three functions: +- symtable = getlibrary(libraryname) + Get a reference to import library libraryname. "InterfaceLib" is the most commonly + used one, containing most toolbox routines. The symbol table can be used + to lookup routines to be passed to newcall: "symtable.WaitNextEvent" will + return the address of routine WaitNextEvent. and so will "symtable['WaitNextEvent']". + The symtable is a mapping, so you can use keys() and len(...) to inspect it. +- symtable = getdiskfragment(file) + Load the specified file (given by fsspec or filename) and return a reference to + its symboltable. +- callable = newcall(routine, returntype, [argtype, ...]) + Return a callable object. You specify the C routine to be called (as explained above), + the type of the return value and the argument types. The resulting object can + be called from Python code in the normal way, and typechecking on arguments is + performed (but, of course, if you specify incorrect argument types in this call + you may well crash your machine). Printing a callable will give you a description + of the (C-) calling sequence. + +The C return value can be one of 'None', 'Byte', 'Short', 'Long', 'Pstring' (a pascal +string returned by address, copied to a Python string), 'Cobject' (a wrapper around a void +pointer), 'Handle' (a new handle, returned as a Res.Resource object) or 'OSErr' (which raises +MacOS.Error if non-zero). + +Arguments can be any of 'InByte', 'InShort', 'InLong', 'InString' (a python string, with the +address of the data passed to the C routine, so be careful!), 'InPstring' (a python string copied +to a Str255 and passed by address), 'InCobject', 'InHandle', 'OutByte' (storage is allocated for +a single byte, the address passed to C and the resulting value returned to Python), 'OutShort', +'OutLong', 'OutPstring' (again: storage pre-allocated and the address passed to C), 'OutCobject' +(storage for a void * is allocated, this void ** is passed to C and the resulting void * is +encapsulated in the Cobject returned) or 'OutHandle' (ditto, which means that this is usually *not* +what you use, you normally use 'InHandle' because most toolbox calls expect you to preallocate +the handle). + +All values to be returned (from the return value and the Out arguments) are collected. If there +aren't any None is returned, if there is one value this value is returned, if there are multiple +values a tuple is returned. + +There is test code in testcalldll.py, and a minimal example in samplecalldll.py. + +Have fun, and let's discuss the design of this thingy on pythonmac-sig, + + Jack Jansen, jack@cwi.nl, 23-May-97. |