In ruby I can do this:
1.9.3-p448 :001 > a = 1 || 2
=> 1
1.9.3-p448 :004 > a = nil || 2
=> 2
1.9.3-p448 :005 > a = 1 || nil
=> 1
Is there a similar one-liner in Python?
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3 Answers
Just use the or operator. From the linked page:
x or y: if x is false, then y, else x
Example:
In [1]: 1 or 2
Out[1]: 1
In [2]: None or 2
Out[2]: 2
In [3]: 1 or None
Out[3]: 1
2 Comments
Python's or operator is pretty much the equivalent of Ruby's || -- and None can be used in Python somewhat similarly to how nil is in Ruby.
So, for example,
a = None or 2
would set a to 2.
You can also use a richer "ternary" operator, something if condition else somethingelse -- a or b is the same as a if a else b -- but clearly or is more concise and readable when what you want to do is exactly the semantics it supports.
1 Comment
Matteo NNZ
I think in Ruby the null syntax is
nil, not null. But I agree with the rest of the answer.Don't forget about modern if-else syntax:
x = a if a is not None else 999
(or whatever condition you need). This let you test for non-None and is not prone to empty list and similar problems.
General syntax is
ValueToBeUsedIfConditionIsTrue if Condition else ValueToBeUsedIfConditionIsFalse
