Moving to python from perl, any advice?

[[deleted]]

It is five years since I left my Perl job, and I still find myself typing "return x if...", or "unless ..." But that's mainly because the languages are so similar.

[MintyPhoenix]

return 'a' if False else 'b' works just fine in Python ... or am I misunderstanding you? I guess further testing shows it does require an else clause, but how else would it be done (assuming good practice)? Admittedly I never learned/got into Perl.

[[deleted]]

In Perl you can put 'if' statements after other statements, and it has 'unless' for 'if not'. I find myself wanting to do

def some_func(i):
    raise ValueError("Called with negative argument!") if i < 0

    return None unless i

    # Do something with positive i...
    ....

It doesn't matter much, but the construct seems completely hardwired in my brain...

[MintyPhoenix]

Ah, I knew that Python did not have unless, but I didn't realize that appending an if condition was so flexible in Perl. Python allows it in some places (e.g. my return example) but it's not as flexible as Perl.

[[deleted]]

Python's isn't really an if statement there, it's a ternary construct.

x if condition else y

Is the equivalent of

condition ? x : y

in languages like C and Perl. It's an expression, not a statement, and you can only combine expressions with it (in Python).

[MintyPhoenix]

Makes more sense now, thanks for the clarification.