[Python-Dev] PEP 318 bake-off? (original) (raw)

Bob Ippolito bob at redivi.com
Thu Apr 1 14:33:24 EST 2004

On Apr 1, 2004, at 2:08 PM, Guido van Rossum wrote:

What I'm asking (especially of Phillip) is to collect a set of realistic method declarations using decorators; we can then collectively format these using any of the possible syntaxes, and see how they look.

I'd be happy to scrounge up some samples from existing code using 'property' and 'classmethod' as well as some of PEAK's decorators, and I definitely think that Jack Diedrich and Bob Ippolito's samples should be included as well. Important question, though: do we include code bodies, or just use 'pass' for the bodies? If we include the body, how much of the body? Should we include entire classes, especially if the class itself needs a decorator, and multiple methods have decorators? Why not provide the bodies, for added realism? (I still think class decorators are a separate case, and much weaker -- you can do this by having a single 'decoratable' metaclass and setting decorators = [...] in the class body.)

Here's something I wrote today.. it's a delegate for the exception handling mechanism so you can listen in on (any of) the exceptions that ObjC throws whether or not they are caught by something else.. the Python->PyObjC exceptions are logged as tracebacks and the ObjC exceptions are thrown over to atos so they turn into human-readable stack traces.

As you can see, it's rather ugly with regular old Python syntax.

class PyObjCDebuggingDelegate(NSObject): def exceptionHandler_shouldLogException_mask_(self, sender, exception, aMask): try: if isPythonException(exception): if self.verbosity() & LOGSTACKTRACE: nsLogObjCException(exception) return nsLogPythonException(exception) elif self.verbosity() & LOGSTACKTRACE: return nsLogObjCException(exception) else: return False except: print >>sys.stderr, "*** Exception occurred during exception handler ***" traceback.print_exc(sys.stderr) return True exceptionHandler_shouldLogException_mask_ = objc.selector(exceptionHandler_shouldLogException_mask_, signature='c@:@@I')

 def exceptionHandler_shouldHandleException_mask_(self, sender,

exception, aMask): return False exceptionHandler_shouldHandleException_mask_ = objc.selector(exceptionHandler_shouldHandleException_mask_, signature='c@:@@I')

the objc.selector signatures say that they return a char (a BOOL, actually), the following @: represents "self" and the selector (the "method name"), the next two @@ say that the sender and exception arguments are both ObjC objects, and the trailing I means that aMask is an unsigned int.

-bob

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