Best way to do conditional assignment in python

Question

I tend to use this a lot, but it's ugly:

a = (lambda x: x if x else y)(get_something())

So I wrote this function:

def either(val, alt):
    if val:
        return val
    else:
        return alt

So you can do:

a = either(get_something(), y)

Is there a built-in function for this (similar to ISNULL in T-SQL)?

Answer 1

The or operator does what you want:

get_something() or y

In fact, it's chainable, like COALESCE (and unlike ISNULL). The following expression evaluates to the left-most argument that converts to True.

A or B or C

Answer 2

You may use:

a = get_something() or y

If get_something is True in boolean context, its value will be assigned to a. Otherwise - y will be assigned to a.

Answer 3

Easy!

For more conditional code:

a = b if b else val

For your code:

a = get_something() if get_something() else val

With that you can do complex conditions like this:

a = get_something() if get_something()/2!=0 else val