On Fri, May 11, 2018 at 12:38 PM, Ian Kelly <ian.g.ke...@gmail.com> wrote:
> Would you also contend that generator functions are wrong because they
> pretend to be normal functions?
>
> def totally_not_a_generator(n):
> while True:
> if n % 2 == 0:
> n //= 2
> else:
> n = n * 3 + 1
> stealthily = n
> yield stealthily
> if n == 1:
> return n
>
> py> print(totally_not_a_generator(42)) # Lies!
> <generator object totally_not_a_generator at 0x77fe4d78c0f8>
Let's see. It's created with 'def'. It can be called by putting
parentheses after its name. Inside the parentheses, you can give it
parameters. When called, it returns a value. Hmm. Sure looks like a
function to me.
Tell me, which of these are functions and which are not?
def tnag5():
return totally_not_a_generator(5)
def tnag(n):
return iter(totally_not_a_generator(n))
def ILY():
return iter([1, 2, 3]) # your heart starts beating
async def what_about_me():
await spam()
return 42
def digits_to_number(text):
return int(text, 10)
class run_command:
"""Compatibility shim for older API"""
def __init__(self, *args):
proc = subprocess.run(*args, stdout=subprocess.PIPE)
self.rc = proc.returncode
self.output = proc.output
def run_command(*args):
proc = subprocess.run(*args, stdout=subprocess.PIPE)
return {"rc": proc.returncode, "output": proc.output}
The only one that inspect.isfunction() returns False for is the class,
and even that is a very function-like class. Every one of these is
callable and will return a useful value. Their headers announce one of
three things:
1) "I am a function" ==> def name(...):
2) "I am a factory for objects of my own type" ==> class name:
3) "I am a coroutine function" ==> async def name(...):
Not one of them is lying. And nor is your totally_not_a_generator. As
Steven said, it's a function, and it returns a value. That's not
materially different from ILY() in my example - it returns something
which you can iterate over.
ChrisA
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