I read PEP 618 (Add Optional Length-Checking To zip)

The other day, PEP 618 (Add Optional Length-Checking To zip) was [committed that it was accepted](https://github. I saw com / python / peps / pull / 1435). So, this time I will read PEP 618.

Overview

• When using the zip () function, you may (often) implicitly expect each element to be the same length.
• If you mistakenly give elements of different lengths, you will unintentionally lose data.

  >>> list(zip([1,2,3], [4]))  # 2,3 will be lost
  [(1, 4)]

• When I have a function like this, passing a list works as intended, but passing an iterator doesn't work (because the iterator goes ahead).

  def apply_calculations(items):
      transformed = transform(items)
      for i, t in zip(items, transformed):
          yield calculate(i, t)

• Add an option to zip () and check that each element is the same length

approach

Python 3.10 added a parameter called strict to thezip ()function. If you specify a positive value for strict, ValueError occurs when the lengths of the elements are not equal.

>>> for item in zip([1, 2, 3], [4], strict=True):
...     print(item)
...
(1, 4)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: zip() argument 2 is shorter than argument 1

I'm getting an error that the second argument of zip () is shorter than the first argument. By the way, it should be noted that the loop runs until it detects that the lengths do not match.

By default, the behavior is the same as before (equivalent to strict = False, that is, if the lengths are different, the data is discarded).

>>> for item in zip([1, 2, 3], [4]):
...     print(item)
...
(1, 4)
>>>

Impressions

• I'm glad this is because I have a feeling that I might inadvertently make a mistake and cause data loss.
• However, you have to explicitly specify strict = True, so it may be a problem if you forget to specify it.
• The iterator example seemed to be confusing (though you'll notice it soon ...)
• I'm looking forward to 3.10