On 17 avr, 14:25, andrew cooke <[EMAIL PROTECTED]> wrote: > On Apr 17, 7:12 am, "[EMAIL PROTECTED]"<[EMAIL PROTECTED]> wrote: > > [...] > > Thanks very much! > > These are useful pointers. I'll update my code accordingly. > > At one point you pointed out I didn't need parentheses and I agree - I > was using them to avoid having a line continuation backslash (I think > I read to do that in a style guide recently).
Ok. I personnaly prefer \ continuations, but that's another troll^M^discussion !-) > One other question. I had "foo is False" and you said I need > equality, which is a good point. However, in any other language "not > foo" would be preferable. And it's indeed the case in Python. > I was surprised you didn't suggest that I did - even if somewhat implicitly -, as Paul brillantly explained. > (and I'm unsure now why I didn't write it that way myself). Is there > some common Python standard that prefers "foo == False" to "not foo"? Definitively not. FWIW, True and False are later additions to Python, which has a much more generic concept of what's true or false (notice the lowercase) in the context of a boolean expression, that is: - False, None, numeric zero are false - an object that has a __nonzero__ method has the truth value of the result of calling this method - a "sizeable" object (one which defines a __len__ method) is true if len(obj) > 0, else it's false (which implies that empty dicts, lists, tuples and strings are false) - anything else is true (please someone correct me if I forgot something here). > > PS Is there anywhere that explains why Decorators (in the context of > functions/methods) are so good? I've read lots of things saying they > are good, but no real justification of why. To me it looks more like > "re-arranging deck chairs on the Titanic" - you're just moving where > the hack happens from one place to another. Is the point that now the > hack is more visible and hence modifiable? I wouldn't call function decorators "a hack" - it's just a pretty common use of HOFs. Now wrt/ the @decorator syntax: yes, you're plain right, the GoodThing(tm) is that it makes the use of the HOF clearly visible at the top of the function definition so you just can't miss it. -- http://mail.python.org/mailman/listinfo/python-list
