Question

I’m just getting started in python, and either haven’t read about this, or missed it, and I don’t know what to search for to find my answer.

Playing around with the IMAP module I came across this line of code.

result, data = mail.search(None, "ALL")

What is happening with the two variables here? Is this a syntax that is used when methods return a certain way, or does it always work? Could someone either explain what’s going on here, or point me to some documentation?

Answer 1

This is a form of sequence unpacking. If the RHS is an iterable of length 2 (since you have 2 objects on the LHS), you can use it. e.g.:

a,b = (1, 2)  #The RHS here is a tuple, but it could be a list, generator, etc.
print a #1
print b #2

Python3 extends this in an interesting way to allow the RHS to have more values than the LHS:

a,b,*rest = range(30) 
print(a) #0
print(b) #1
print(rest == list(range(2,30))) #True