Steve Holden wrote:
> Paul Rubin wrote:
>> Steve Holden <[EMAIL PROTECTED]> writes:
>>> Assuming you're right, what alternative would you suggest? Would it
>>> allow parenthesized expressions to retain their customary meaning?
>>
>> It is kind of weird that there is even such a thing as a 1-tuple.
>
> I agree that zero-length and singleton tuples don't make a great deal of
> sense semantically.
Why not? They seem intuitive to me. I would find it weird if you
couldn't have 0-tuple, and even weirder if you couldn't have a 1-tuple.
Maybe my brain has been warped by too much C++ code.
In C++, it's very common to define data structures that have no members;
the moral equivalent of an empty tuple:
struct S { };
I recently did this in C, and was surprised to see this message from gcc:
main.c:1: warning: struct has no members
It's also common in C++ to treat a stand-alone object as an array of
length 1. This is useful because any function defined to take a
sequence of input can easily be given a single element instead:
int proto = 5;
std::vector<int> v(&proto, &proto + 1);
It strikes me that 1-tuples could serve the same purpose. It's common
now for functions to be defined to take single elements, with client
code using loops to process sequences:
for item in sequence:
process(item)
If functions were instead defined to take sequences, then client code
would be simplified, especially for common tasks like processing lines
of input.
process(sequence)
On occasions when only a single item were to be processed, a 1-tuple
would serve as a nice syntactic adapter:
process((item,))
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