On Mon, Mar 07, 2005 at 08:58:44PM -0800, David Storrs wrote:
: Ok, rewrite; is THIS legal?:
:
: sub foo( Int [EMAIL PROTECTED] is shape(3) ) { ... }
: foo(1, 2, undef);
Yes, since Int can represent undef.
: The sense I'm trying to convey is:
:
: "Here is my sub. It takes three ints."
:
: "Here is me calling the sub. I am giving you only two ints and
: explicitly telling you [by explicitly passing undef] that I meant
: to do that so just take it and be quiet."
:
: To put it another way...in perl5, a sub that was prototyped to take
: three scalar args will throw an error when you pass only two but will
: accept it if you pass two plus an explicit undef. On the other hand,
: if it was prototyped to take an array there is no way to tell the
: difference between an explicitly-passed undef and a too-short arg
: list. How will P6 handle these two scenarios?
Could use "exists", maybe. Though for an array with shape(3)
it's possible that exists(@a[2]) is always true regardless of the
bound value. On the other hand, binding an array that is too short
is going to be a type mismatch, so you probably can't get into the
situation of a shaped array being too short to begin with. It'll
either fail immediately in the case of a normal sub, or it'll
go off looking for something else to MMD to that doesn't violate
any type constraints, and fail if it doesn't fine one.
Larry
