Bruno Desthuilliers wrote: > Boris Borcic a écrit : > > Hello Bruno, > > > > Bruno Desthuilliers wrote: > > > >> Boris Borcic wrote: > >> > >>>> Do you have any ideas? > >>> > >>> > >>> you could use a recursive generator, like > >>> > >>> def genAllChildren(self) : > >>> for child in self.children : > >>> yield child > >>> for childchild in child.genAllChildren() : > >>> yield childchild > >> > >> > >> > >> Or how to *not* address the real problem... > >> > >> Boris, using a generator may be a pretty good idea, but *not* as a way > >> to solve a problem that happens to be a FAQ !-) > >> > > > > Sorry, but I don't understand your reasoning. > > It's quite simple. The OP's problem is well-known (it's a FAQ), and easy > to solve. The righ answer to it is obviously to give a link to the FAQ > (or take time to re-explain it for the zillionth time), not to propose a > workaround. > > > How can you exclude that > > the OP /may/ find that a generator neatly solves his problem ? > > I don't exclude it, and explicitly mentioned in whole letters that, I > quote, it "may be a pretty good idea". And actually, the OP's problem is > really with default values evaluation scheme - something that every > Python programmer should know, because there are cases where you cannot > solve it with a generator-based solution !-) > > > The use > > of a default value was not an end in itself, was it ? > > If the OP has other reasons to want to use an accumulator based solution > - which we don't know - then the possibility to use a default value is > important. > > > - and the quirks of > > default values being FAQ stuff don't change that. Sure if nobody had > > covered that aspect, but a couple other posters did... > > Yes, but you forgot to mention that - and I would not have post any > comment on your solution if you had explicitly mentioned the FAQ or > these other answers. > > > Mmmmhhh somehow it feels like if there is any issue here, it is about > > defending the credo "there ought to exist only one obvious way to do it" > > ?... > > Nope, it's about trying to make sure that anyone googling for a similar > problem will notice the canonical solution somehow.
Sorry, but I kinda agree with Boris here. Not that I am anybody here, really. If the question is to use an accumulator based solution, then yes, the default values answer is definitely the canonical solution. If the question is to write a recursive function that returns a list, an accumulator based solution and a generator based solution are two different ways for doing that. I don't think there is actually a FAQ saying you must use the accumulator solution. Actually, the accumulator based solution kind of comes to me automatically as standard in any programming language, and I believe that this was established as standard in python, _before_ the introduction of generators. Now, personally I find the generator-based solution more intuitive for me (in the eys of the beholder:). And, looking at the subject of the thread, guess what was the question? k -- http://mail.python.org/mailman/listinfo/python-list
