Re: is static?

[Damian Conway]

Larry wrote:

: sub foo() {
:     has $s //= 0; 
:     $s ++ ;
: }
: 
: print foo, foo, foo; 
This is interesting, but I think it would be a mistake to give C<has> two 
unrelated meanings -- and I think we'd have to stretch our concepts of objects 
a little too far to consider these two meanings related. (Yes, *I* can easily 
stretch my mind to envisage the "attributes of a subroutine", but should 
everyone else have to?)

Futhermore, this approach opens another vermiferous can. I would argue that 
C<//=> is the wrong way to initialize it, since that effectively prevents 
C<undef> values from being used with such variables.

Curiously we have already felt the lack of an assign-on-non-existence 
initializer elsewhere...for optional parameters. Perhaps we have not yet have 
gone far enough in mirroring the various levels of reality that a value can 
aspire to:

	Function	Assign unless...

         true                ||=
        defined              //=
        exists             hmmmmmmmm
One is almost tempted by something like C<??=>. Well, almost.

But back to the topic of discussion. I have argued for some considerable time 
that this "static variable" *functionality* is extremely useful and much 
tidier than the current alternative:

        { my $s = 0;
          sub foo() {
              $s++;
          }
        }
But using Yet Another Declarator is, I believe, the wrong approach.
The variable $s is a regular lexical variable in every respect, save one: it 
has the unusual trait that is retained from call to call of its surrounding code.

Hence, I would argue, one ought to simply mark it with a trait:

        sub foo() {
           my $s is retained = 0;
           $s++;
        }
Other possible trait names:

        is kept
        is preserved
        is permanent
        is reused
        is saved
        is stored
        is restored
        is irrepressible
Yes, the names are all considerably longer than a C<has> declarator, but I see 
that as a bonus. Persistent behaviour by a lexical is unusually enough that it 
ought to be loudly and clearly marked.

Oh, and note that I very deliberately did not suggest C<is static>!

Damian