On: Why is perl losing its touch?

[tomjen3]

Python is often claimed not to have closures but that isn't really true, what it doesn't have is anonymous functions. It does have a lambda statement, but that is limited to a single statement.

So what you end up writing is more akin to:

    def multiplier_maker(a):
      def temp(b):
        return b * a
      return temp

That is because Python allows you to declare a function anyware, even inside other functions.

[sebleblanc → tomjen3]

And if you want to emulate static variables in a function, you can do that:

    def counter():
        counter.x += 1
        return counter.x

    counter.x = 0
    counter()
    > 1
    counter()
    > 2

Beware! singleton variables, mutable state, etc.

[knome → sebleblanc]

You can do it by closing over a variable as well. Python closes over things just fine, it just has problems rebinding variables in outer scopes that aren't the global one. Here, I just make the variable a container, so I can alter a value inside it, instead of rebinding it ( only python2 has this problem, python3 has a "nonlocal" keyword to work around this in the language )

    >>> def counter():
    ...   x = [ 1 ]
    ...   def count():
    ...     y = x[ 0 ]
    ...     x[ 0 ] += 1
    ...     return y
    ...   return count
    ... 
    >>> count = counter()
    >>> count()
    1
    >>> count()
    2
    >>> count()
    3
    >>> count()
    4
    >>> 
    >>> otherCount = counter()
    >>> otherCount()
    1
    >>> otherCount()
    2
    >>> count()
    5
    >>> count()
    6
    >>> otherCount()
    3
    >>>

[jafaku → tomjen3]

> what it doesn't have is anonymous functions

If it's not anonymous it's not a closure though.

[tomjen3 → jafaku]

Bullshit. It closures around its environment, it is a closure.