Front page | perl.perl6.language |
Postings from April 2005
On Fri, 22 Apr 2005 11:42:10 -0400, Larry Wall <larry@wall.org> wrote:
>
> You speak of "open" as if it must be a single function. We're now
> living in the age of MMD, so what you're asking for is a no-brainer.
> If we decided to we could even do MMD with constraints:
>
> multi sub open ($u of Str where /^file:/, *@opts) returns Handle
> {...}
> multi sub open ($u of Str where /^http:/, *@opts) returns Handle
> {...}
> multi sub open ($u of Str where /^ftp:/, *@opts) returns Handle {...}
> multi sub open ($u of Str where /^mailto:/, *@opts) returns Handle
> {...}
> ...
>
> Though that would potentially be problematic if you wanted to open
> a file whose name started with "http:", so we'd probably want to
> give that suite of multis a different name. Call it io() maybe, if
> we can unify the Handle and IO abstractions. As I've said before,
> I kinda like the IO::All module, except for how it overloads < and >.
> But Perl 6 has ==> and <== that can do that instead, which just happen
> to be called "pipes", strange coincidence. :-)
Well why can't you define the functions like so:
multi sub open ($u of Str where /^file:\/\//, *@opts) returns Handle {...}
multi sub open ($u of Str where /^http:\/\//, *@opts) returns Handle {...}
multi sub open ($u of Str where /^ftp:\/\//, *@opts) returns Handle {...}
multi sub open ($u of Str where /^mailto:\/\//, *@opts) returns Handle
{...}
Also, I don't know much about rules with regex yet, but could you do
something like...
multi sub open ($u of Str where /<protocol(file)>/, *@opts) returns
Handle {...}
Where < <protocol(file)> > expands to < file:// >
Thread Previous
|
Thread Next