Tuple Syntax and ()

[tactics40]

I keep accidently trying to declare t-tuples as mytuple = (myitem)

I know this doesn't work and that you need the trailing comma, but
reading something online, I just came to realize.... the parenthesises
don't have any special meaning in relation to tuples at all, do they?

[James Stroud]

ta*******@gmail.com wrote:

I keep accidently trying to declare t-tuples as mytuple = (myitem)

I know this doesn't work and that you need the trailing comma, but
reading something online, I just came to realize.... the parenthesises
don't have any special meaning in relation to tuples at all, do they?

Aside from grouping, they are special to construct an empty tuple.

py> () == tuple()
True

Also, don't underestimate their relationship with tuples when it comes
to grouping:

py> a, b, c = 1, 2, 3
py>
py> a == a, b, c
(True, 2, 3)
py> a == (a, b, c)
False

James

--
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095

http://www.jamesstroud.com/

[Steve Holden]

ta*******@gmail.com wrote:

I keep accidently trying to declare t-tuples as mytuple = (myitem)

I know this doesn't work and that you need the trailing comma, but
reading something online, I just came to realize.... the parenthesises
don't have any special meaning in relation to tuples at all, do they?

Give that (?)man a cigar! The only time the parentheses are necessary is
when you need to disambiguate - the most frequent needs are:

() for an empty tuple: there's no other way to express that without
using tuple(), and

f((a, b, ...)) to provide a single tuple argument to a function.

regards
Steve
--
Steve Holden [phone] [phone]
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