[Tutor] product of all arguments passed to function call

[Peter Otten]

On 31/05/2021 12:19, Alan Gauld via Tutor wrote:

> def product(*x):
>      result = 1 if x else 0
>      for n in x:
>        result *= n
>      return result

The result of an empty product is usually the "multiplicative identity", 
i. e. 1 in the majority of cases. If there were a result for the 
no-arguments case I'd pick that.

Another problem with your implementation is that you are making 
assumptions about the arguments, thus defeating Python's duck typing. I 
admit the example is a bit farfetched, but anyway:

 >>> class S(str):
	def __imul__(self, other):
		return S(f"{self}*{other.strip()}")

	
 >>> def product(*x):
     result = 1 if x else 0
     for n in x:
       result *= n
     return result

 >>> product(S("a"), "b ", "   c   ")
Traceback (most recent call last):
   File "<pyshell#367>", line 1, in <module>
     product(S("a"), "b ", "   c   ")
   File "<pyshell#366>", line 4, in product
     result *= n
TypeError: can't multiply sequence by non-int of type 'str'

Whereas:

 >>> def product(x, *y):
	for yy in y:
		x *= yy
	return x

 >>> product(S("a"), "b ", "   c   ")
'a*b*c'

There is prior art (sum() and strings), I don't like that either ;)