Re: decorators - more than just syntactic sugar
On 8/13/07, Bjoern Schliessmann [EMAIL PROTECTED] wrote: BJörn Lindqvist wrote: unpedagogically not separated from ordinary functions. Decorators _are_ ordinary functions. Remember the syntactic sugar in this thread? Remember also that syntactic sugar is important. Case in point, the OP did not think of looking at the built-in functions page. -- mvh Björn -- http://mail.python.org/mailman/listinfo/python-list
Re: decorators - more than just syntactic sugar
On Aug 11, 8:30 pm, Helmut Jarausch [EMAIL PROTECTED] wrote: Hi, are decorators more than just syntactic sugar in python 2.x and what about python 3k ? Well, I argued may times that syntactic sugar is important (all Turing complete languages differs by syntactic sugar only) and having or not having a given syntactic sugar makes a difference between writing and not writing a given program. Having decorators in core Python makes us think differently. Have a look at David Mertz article http://www.ibm.com/developerworks/linux/library/l-cpdecor.html Michele Simionato -- http://mail.python.org/mailman/listinfo/python-list
Re: decorators - more than just syntactic sugar
On Aug 11, 8:30 pm, Helmut Jarausch [EMAIL PROTECTED] wrote: How can I find out the predefined decorators? I dare to say that's not easy. Since decorators are just(?) syntactical sugar they don't obtain a particular semantics expressed by distinctive declarative elements. Unlike generators which can be identified looking for a yield expression a decorator can be identified syntactically just when it is used. However this might be sufficient, depending on your intention? -- http://mail.python.org/mailman/listinfo/python-list
Re: decorators - more than just syntactic sugar
On 8/11/07, Helmut Jarausch [EMAIL PROTECTED] wrote: How can I find out the predefined decorators? There are two in the standard library, @classmethod for declaring class methods and @staticmethod for declaring static methods. They are listed at the built ins page http://docs.python.org/dev/lib/built-in-funcs.html, unpedagogically not separated from ordinary functions. -- mvh Björn -- http://mail.python.org/mailman/listinfo/python-list
Re: decorators - more than just syntactic sugar
BJörn Lindqvist [EMAIL PROTECTED] wrote: On 8/11/07, Helmut Jarausch [EMAIL PROTECTED] wrote: How can I find out the predefined decorators? There are two in the standard library, @classmethod for declaring class methods and @staticmethod for declaring static methods. They are listed at the built ins page http://docs.python.org/dev/lib/built-in-funcs.html, unpedagogically not separated from ordinary functions. There are at least two other decorators in the standard library: functools.wraps contextlib.contextmanager -- http://mail.python.org/mailman/listinfo/python-list
Re: decorators - more than just syntactic sugar
Marc 'BlackJack' Rintsch [EMAIL PROTECTED] wrote: On Sat, 11 Aug 2007 20:30:54 +0200, Helmut Jarausch wrote: are decorators more than just syntactic sugar in python 2.x and what about python 3k ? They are just syntactic sugar. @spam def ham(): pass is the same as def ham(): pass ham = spam(ham) Decorators are almost just syntactic sugar, but in fact there is a subtle difference between the two bits of code you gave: in the second one you assign the function to the name ham and then replace it with the result of calling spam. With the decorator syntax you only have one assignment to ham and when that decorator is called that assignment has not yet happened. The difference is small, but you can write decorators which depend on it. For example, the code I posted in [EMAIL PROTECTED] depends on this difference and will not work if you write the calls out explicitly instead of using decorators. -- http://mail.python.org/mailman/listinfo/python-list
Re: decorators - more than just syntactic sugar
Michele Simionato [EMAIL PROTECTED] writes: On Aug 11, 8:30 pm, Helmut Jarausch [EMAIL PROTECTED] wrote: Hi, are decorators more than just syntactic sugar in python 2.x and what about python 3k ? Well, I argued may times that syntactic sugar is important (all Turing complete languages differs by syntactic sugar only) Although I agree that mere syntactic sugar matters, I think you're overstating the point. I would argue that most people would understand syntactic sugar as equivalent to a (very) localized program transformation. Things like first class continuations clearly aren't syntactic sugar in that sense. 'as -- http://mail.python.org/mailman/listinfo/python-list
Re: decorators - more than just syntactic sugar
BJörn Lindqvist wrote: unpedagogically not separated from ordinary functions. Decorators _are_ ordinary functions. Remember the syntactic sugar in this thread? Regards, Björn -- BOFH excuse #338: old inkjet cartridges emanate barium-based fumes -- http://mail.python.org/mailman/listinfo/python-list
Re: decorators - more than just syntactic sugar
On Aug 13, 7:46 pm, Alexander Schmolck [EMAIL PROTECTED] wrote: Michele Simionato [EMAIL PROTECTED] writes: Well, I argued may times that syntactic sugar is important (all Turing complete languages differs by syntactic sugar only) Although I agree that mere syntactic sugar matters, I think you're overstating the point. I would argue that most people would understand syntactic sugar as equivalent to a (very) localized program transformation. Things like first class continuations clearly aren't syntactic sugar in that sense. 'as I don't think I am overstating my point. I am just pointing out a sloppiness in the definition of syntactic sugar. You are right that most people understand it as °a somewhat trivial program transformation. However most people tend to forget that by a succession of somewhat trivial program transformations you can get quite a lot. Look, a compiled language is just a whole big lot of syntactic sugar over assembly language! An even continuations can be implemented in terms of macros. the quintessence of syntactic sugar (as you know better than me). You are right that this require a global program transformation, it is a kind of heavy duty syntactic sugar, but still it is always syntactic sugar at the end. Then, you may decide that you want to use a different name from global program transformation, since syntactic sugar sounds diminutive, but then it is an issue of names ;) Michele Simionato -- http://mail.python.org/mailman/listinfo/python-list
Re: decorators - more than just syntactic sugar
On Sat, 11 Aug 2007 20:30:54 +0200, Helmut Jarausch wrote: are decorators more than just syntactic sugar in python 2.x and what about python 3k ? They are just syntactic sugar. @spam def ham(): pass is the same as def ham(): pass ham = spam(ham) How can I find out the predefined decorators? *The* predefined decorators? Decorators are just functions after all. There are some meant to be used as decorators but there are also ordinary functions that may make sense as decorators. Ciao, Marc 'BlackJack' Rintsch -- http://mail.python.org/mailman/listinfo/python-list
