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To: "Joe Gottman" <jgott...@carolina.rr.com>
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Subject: Re: A6: overloading multis on constness of parameters
Date: Thu, 13 Mar 2003 00:15:42 +0000
In-Reply-To: <004d01c2e83b$47b8c0c0$cf6e1918@carolina.rr.com> ("Joe Gottman"'s message of "Tue, 11 Mar 2003 21:01:21 -0500")
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From: pdcaw...@bofh.org.uk (Piers Cawley)
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"Joe Gottman" <jgott...@carolina.rr.com> writes:

>    Will it be possible in perl6 to overload multis on the const-ness of a
> parameter, like C++ does?  For instance,
>
>    multi getX(Foo $self:) returns Int {...} #const version
>    multi getX(Foo $self: is rw) returns Int is rw {...} #non-const version
>
>    If getX were called on a const Foo object then the first getX would be
> called, and if it were called on a non-const Foo object the second one would
> be.

Speaking of multis and constants, Greg McCarroll wondered on IRC if
this would work:

    multi factorial (Int 0) { 1 }
    multi factorial (Int $n) { $n * factorial($n-1) }

Disregarding the fact that you should really write that as:


    sub factorial (Int $n) {
        my multi tail_fac ($result, 0) { $result }
        my multi tail_fac ($result, $n) { tail_fac( $result * $n, $n - 1 ) }
        tail_fac(1, $n);
    }

(Assuming you want to do it recursively that is...)


-- 
Piers