Awesome Cross the Finish Line Rakudo Perl 6 Grant
This is the new addition near top of Perl 6 wiki to thank Ian Hague (and to help counter public skepticism about the prospects of Perl 6): Awesome Cross the Finish Line grant for Rakudo Perl 6 Thank you Ian Hague! * See TPF receives large donation in support of Perl 6 developmentlink. * This should see us through the first official early production-level release of Rakudo Perl 6. * Please consider following Ian's example. ** There's still a lot of additional valuable support work that could also be done on Perl 6, Parrot, key Perl 6 CPAN modules, and so on. Best regards, Conrad Schneiker www.AthenaLab.com Official Perl 6 Wiki http://www.perlfoundation.org/perl6 Official Parrot Wiki http://www.perlfoundation.org/parrot
Re: assignable mutators (S06/Lvalue subroutines)
HaloO,
John M. Dlugosz wrote:
I have similar thoughts. I'm thinking that some macros will aid in
writing proper setters via a tie-like mechanism that don't require any
core language changes, so it's not a real problem. That is, a reusable
proxy class that you can construct to run the setter body code, and
package it up so you write it like a method.
If I get you write, you want some magic to convert
$obj.attr = 42;
into
$obj.attr(42);
so that one can write the attr method as if it had a single
parameter without actually doing so. E.g.
class Blah
{
method attr is setter
{
self.blahh = rhs; # rhs gives 42 above
}
# magically same as
# method attr ($rhs)
# {
#self.blahh = $rhs;
# }
}
I wonder if that couldn't simply be
method attr is rw
{
return self.blahh;
}
Or am I missing something?
Regards, TSa.
--
The unavoidable price of reliability is simplicity -- C.A.R. Hoare
Simplicity does not precede complexity, but follows it. -- A.J. Perlis
1 + 2 + 3 + 4 + ... = -1/12 -- Srinivasa Ramanujan
Re: assignable mutators (S06/Lvalue subroutines)
On 2008 May 26, at 10:19, TSa wrote:
John M. Dlugosz wrote:
I have similar thoughts. I'm thinking that some macros will aid in
writing proper setters via a tie-like mechanism that don't require
any core language changes, so it's not a real problem. That is, a
reusable proxy class that you can construct to run the setter body
code, and package it up so you write it like a method.
I wonder if that couldn't simply be
method attr is rw
{
return self.blahh;
}
Or am I missing something?
What if you want to store a modification of the value? e.g.
compatibility method to set a length in inches when the stored length
is in millimeters.
--
brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED]
system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED]
electrical and computer engineering, carnegie mellon universityKF8NH
Re: assignable mutators (S06/Lvalue subroutines)
HaloO,
I wrote:
I wonder if that couldn't simply be
method attr is rw
{
return self.blahh;
}
Or am I missing something?
Hmm, I forget something along the lines of
method attr ($rhs)
{
if $rhs 10 { return self.blahh }
else { return self.blubb }
}
which might be with my concept of equality of object as instance of
a class and of a method invocation as instance of a method class
written as
method attr is rw
{
yield $rhs; # coroutine like return
# we resume here after assignment
if $rhs 10 { self.blahh = $rhs}
else { self.blubb = $rhs}
}
The yield there will return the current invocation of the method
as assignment proxy. The assignment operator needs to be overloaded
for this type something like this
multi sub infix:=(AssignmentProxy $lhs, $rhs)
{
$lhs.resume($rhs);
}
With this in place an AssignmentProxy might actually work as rvalue,
too. Thus one can drop the 'is rw' from attr and all the magic is in
the yield declarator/statement.
class Obj
{
has $.foo = 'foo';
has $.blubb = 'blubb';
has $.blahh = 'blahh';
method attr
{
yield $rhs = self.foo;
if $rhs 10 { self.blahh = $rhs}
else { self.blubb = $rhs}
}
}
my $x = Obj.new;
say $x.attr; # prints 'foo'
$x.attr = 42;
say $x.blahh; # prints 42
So the return type of a yield might actually be ResumeProxy:
sub foo ($x, $y)
{
my $count = 0;
while $count $y - $x { yield ++count; }
yield -1 while True;
}
say foo(7,23).resume.resume; # prints 3
my $f = foo(10,15);
say $f; # prints 1
$f.resume while $f != -1;
say $f; # prints -1
Regards, TSa.
--
The unavoidable price of reliability is simplicity -- C.A.R. Hoare
Simplicity does not precede complexity, but follows it. -- A.J. Perlis
1 + 2 + 3 + 4 + ... = -1/12 -- Srinivasa Ramanujan
Re: assignable mutators (S06/Lvalue subroutines)
HaloO,
Brandon S. Allbery KF8NH wrote:
What if you want to store a modification of the value? e.g.
compatibility method to set a length in inches when the stored length is
in millimeters.
As outlined in my afterthought:
class Length
{
has Num $.mm is rw = 0;
method inch
{
yield $inch = $.mm * 25.4;
self.mm = $inch / 25.4;
}
}
Would you regard that as elegant?
Regards, TSa.
--
The unavoidable price of reliability is simplicity -- C.A.R. Hoare
Simplicity does not precede complexity, but follows it. -- A.J. Perlis
1 + 2 + 3 + 4 + ... = -1/12 -- Srinivasa Ramanujan
