Op 19-09-17 om 09:40 schreef Chris Angelico: > On Tue, Sep 19, 2017 at 5:10 PM, Antoon Pardon <antoon.par...@vub.be> wrote: > >> I don't find it really usefull. How useful is it that you can type >> if a: instead of if a != 0: ? I have yet to encounter a situation >> where I thought: Yes I want to execute this piece of code when >> a value is Falsy and an other piece when that same value is Truthy. > Okay. Let me ask you a different question. > > Given that you can do this: > > if x > 5: > > should you be able to do this: > > condition = (x > 5) > if condition: > > ? If "no", then you've just downgraded booleans to less than > first-class values. If "yes", then you've just opened up the > possibility for "if x:", and you have to draw the line somewhere - > what can you and what can't you use that way? It's now syntactically > legal to use "if x:" with any type of object, so you have to either > define the truthiness/falsiness of everything, or have some of them > raise TypeError.
Yes you have to draw the line somewhere. But there is a difference between one the one hand stating that the line had to be drawn somewhere and that through design and history this is what we ended up with and although it may be interesting to argue the pro and con of this and various other possibilities, this is workable and so highly unlikely to change. or on the other hand stating or suggesting this is the obvious place to draw that line and we would miss something really useful had the line be drawn somewhere else. -- Antoon Pardon -- https://mail.python.org/mailman/listinfo/python-list
