Python conditional assignment operator

python variables conditional
Hartator picture Hartator · Jun 19, 2011 · Viewed 96k times · Source

Does a Python equivalent to the Ruby ||= operator ("set the variable if the variable is not set") exist?

Example in Ruby :

 variable_not_set ||= 'bla bla'
 variable_not_set == 'bla bla'

 variable_set = 'pi pi'
 variable_set ||= 'bla bla'
 variable_set == 'pi pi'

Answer

Keith Devens picture Keith Devens · Jul 10, 2011

I'm surprised no one offered this answer. It's not as "built-in" as Ruby's ||= but it's basically equivalent and still a one-liner:

foo = foo if 'foo' in locals() else 'default'

Of course, locals() is just a dictionary, so you can do:

foo = locals().get('foo', 'default')

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