PEP 572: Python assignment expressions has been accepted

Re:PEP 572: Python assignment expressions has been accepted by PurpleRamen on Tuesday July 03, 2018 @06:53AM (#17449096)

    match = re.match(r1, s)
    if match:
        o = match.group(1)
    else:
        match = re.match(r2, s)
        if match:
            o = match.group(1)

or a bit shorter:

    match = re.match(r1, s)
    if not match:
        match = re.match(r2, s)
    if match:
        o = match.group(1)

You could also just loop:

    for pattern in (r1, r2, ...):
        match = re.match(pattern, s)
        if match:
            o = match.group(1)
            break
    else:
        do_failure_handling()

But this goes a bit beyond the original question.

[ Parent | on HN ]

Re:PEP 572: Python assignment expressions has been accepted by cup-of-tea on Tuesday July 03, 2018 @09:25AM (#17449950)

I made a mistake in the question, it should have been:

    if (match := re.match(r1, s)):
        o = match.group(1)
        # plus some code here
    elif (match := re.match(r2, s)):
        o = match.group(2)
        # plus some other code here

In this case only your first solution works, I think. Leaving aside that having those deeply nested ifs is incredibly ugly, I find it hard to accept that something which completely changes the possible structure of the code is just "syntactic sugar".

[ Parent | on HN ]

Re:PEP 572: Python assignment expressions has been accepted by PurpleRamen on Tuesday July 03, 2018 @09:59AM (#17450207)

It's the syntactic sugars job to beautify the ugly. And your example is also a bit unfair, because you also use another syntactic sugar, the elif, to make it more beautyful. It only falls back to the ugly solution because I can't sweeten sugar for a similar dish.

But the overall question is: when is the sugar just syntactical, and at what point does it become a complete new taste?

[ Parent | on HN ]

Re:PEP 572: Python assignment expressions has been accepted by Demiurge on Tuesday July 03, 2018 @11:58PM (#17455182)

Why is it incredibly ugly when it actually conveys the explicit logic of that which is happening? Can the logic be simplified? Are there any unnecessary characters? I don't see that. This is why I like Python, it's easy to read, and it is easy to refactor and see how you can improve the logic.

[ Parent | on HN ]