28.02.18 16:56, Chris Angelico пише:
def g():
for x in range(5):
y = f(x)
yield [y, y]
stuff = list(g)
You're not the first to mention this, but I thought it basically
equivalent to the "expand into a loop" form. Is it really beneficial
to expand it, not just into a loop, but into a generator function that
contains a loop?
It is slightly faster (if the list is not too small). It doesn't leak a
temporary variable after loop. And in many cases you don't need a list, an
iterator would work as well. In these cases it is easy to just drop calling
list().
Doesn't leak a temporary? In Python 3, the list comp won't leak
anything, but the function is itself a temporary variable with
permanent scope. You're right about the generator being sufficient at
times, but honestly, if we're going to say "maybe you don't need the
same result", then all syntax questions go out the window :D
Explicit for loop leaks variables x and y after the loop. They can hold
references to large objects. The generator function itself doesn't hold
references to the proceeded data.
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