x, = y (???)

Andrew Freeman alif016 at gmail.com
Fri Jul 18 17:18:13 CEST 2008


kj wrote:
>
> I just came across an assignment of the form
>
>   x, = y
>
> where y is a string (in case it matters).
>
> 1. What's the meaning of the comma in the LHS of the assignment?
> 2. How could I have found this out on my own?
>
> (Regarding (2) above, I consulted the index of several Python
> reference books but I could not find the answer to (1).  I hope to
> find a better Python reference!)
>
> TIA!
>
> kynn
>   

Try this:
 >>> y = 'abc'
 >>> type(y)
<type 'str'>
 >>> type((y,))
<type 'tuple'>
 >>> y = y,   # y, is just short for (y,) you *have* to use a coma in 1 
length tuples
 >>> y
('abc',)
 >>> type(y)
<type 'tuple'>
 >>> y[0]
'abc'
 >>> x, = y   #same as x = y[0] OR more verbosely (x,) = (y,)
 >>> x
'abc'
 >>> type(x)
<type 'str'>

Maybe that will hape you understand what the comma is for?



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