Nicholas,
This is addressed in S11, here is a link:
http://search.cpan.org/~ingy/Perl6-Bible/lib/Perl6/Bible/S11.pod
To summarize, the syntax to load the modules is:
use Dog-1.2.1;
While the syntax to create a specific version of a module is:
my Dog-1.3.4-cpan:JRANDOM $spot .= new("woof");
I addresses the class creation syntax partially in the initial
version of the Metamodel prototype, which was built in p5. I
basically just aliased the package with the long name (%{"Dog-1.3.4-
cpan:JRANDOM::"} = %{"Dog::"}). However this does no good for loading
of modules.
I have been giving this some though though, and here is a rough
sketch of what I have come up with so far.
Any module loaded is stored into *:: (or the p5 *main::) as the
longest name given. This means that if I do this:
use Dog-1.2.1-cpan:JRANDOM;
Then I have an entry for "Dog-1.2.1-cpan:JRANDOM" in the symbol
table. If, further along in the compilation process, I encounter
another Dog, such as:
use Dog-0.0.2-cpan:LWALL;
Then this is added as "Dog-0.0.2-cpan:LWALL" into the main symbol
table. Then once the compilation process is complete, I traverse the
symbol table hierarchy collecting all the names. Any duplicate short
names (Dog) are noted for later. Once I have collected all the names,
I build all my aliases.
So if I find:
use Cat-0.0.1-cpan:JRANDOM;
only once, I build an alias for (at a minimum) "Cat" and "Cat-0.0.1".
For my duplicates, the table would look something like this I think:
Dog => Dog-1.2.1-cpan:JRANDOM
Dog-1.2.1 => Dog-1.2.1-cpan:JRANDOM
Dog-0.0.2 => Dog-0.0.2-cpan:LWALL
We are explictly giving the preference to the later version number (I
think we discussed this at the Toronto hackathon).
Another school of thought would be that "Dog" alone would be
considered ambiguious and so we would just alias far enough to be
clear, like this:
Dog => Ambiguity Error!
Dog-1.2.1 => Dog-1.2.1-cpan:JRANDOM
Dog-0.0.2 => Dog-0.0.2-cpan:LWALL
Of course, this means that if I also load "Dog-1.2.1-cpan:LWALL" that
the table looks like this:
Dog => Ambiguity Error!
Dog-1.2.1 => Ambiguity Error!
Dog-0.0.2 => Dog-0.0.2-cpan:LWALL
And the user is now forced to add the cpan id to get Dog-1.2.1. I am
not sure how strict @Larry wants this to be.
I have been meaning to do some kind of p5 prototype of this, I can
push it up the TODO list if it would help you.
Stevan
On Oct 18, 2005, at 5:41 PM, Nicholas Clark wrote:
Sorry if I'm asking a question that I've missed in a synopsis.
Perl 6 will be able to load more than one version of the "same"
module.
As I understand it, this would let you have more than one version of
"DBI" loaded in the same interpreter, and also have DBI written by
Tim Bunce
and "DBI" written by A.U.Thor in the same interpreter.
Is the syntax for accessing different versions of the same module
from Perl
nailed down yet?
Specifically this is in reference to wondering if the multiple
module trick
would actually be possible in perl 5:
http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2005-10/
msg00585.html
and how to do something functionally like:
my $foo = DBI(1.38)->new();
my $bar = DBI(1.40)->new();
or whatever to distinguish which you wanted to call a class method on.
Nicholas Clark
