Recursive function returning a list

[Bruno Desthuilliers]

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.