Re: Object Contruction

2015-03-18 Thread Moritz Lenz 

Hi

On 03/18/2015 01:06 PM, Tom Browder wrote:

My new object needs some methods run during construction.  How can I
do that without defining my own new method?


http://doc.perl6.org/language/objects#Object_Construction lists at least 
two possible ways. Probably the most interesting one is BUILDALL with a 
callsame; see the last example (or example skeleton) in that section.


Cheers,
Moritz

Re: Object Contruction

2015-03-18 Thread Tom Browder 
On Wed, Mar 18, 2015 at 7:22 AM, Moritz Lenz mor...@faui2k3.org wrote:
...
 http://doc.perl6.org/language/objects#Object_Construction lists at least two
 possible ways. Probably the most interesting one is BUILDALL with a
 callsame; see the last example (or example skeleton) in that section.

Thanks, Moritz, I read that but it's a bit confusing to me.  I'll
experiment with it some more and hopefully have some more specific
questions.

Best,

-Tom

Re: Object Contruction

2015-03-18 Thread Tom Browder 
On Wed, Mar 18, 2015 at 11:32 AM, Tom Browder tom.brow...@gmail.com wrote:
 On Wed, Mar 18, 2015 at 7:22 AM, Moritz Lenz mor...@faui2k3.org wrote:
 ...
 http://doc.perl6.org/language/objects#Object_Construction lists at least two
 possible ways. Probably the most interesting one is BUILDALL with a
 callsame; see the last example (or example skeleton) in that section.

For my purposes I think the BUILD is best.  The BUILDALL method seems
to put me in limbo as far as the constructed object and using self.

I made a simple class and a driver Perl script:

$ cat T.pm HERE_PM
class T;

has $.a is rw;
has $.b is rw;
has $.c is rw;

submethod BUILD(
# set defaults here
:$!a = 15,
:$!b,
:$!c,
  ) {
  self.set_b;
}

multi method set_b {
  if (self.a  10) {
self.b = 1;
  }
  else {
self.b = 0;
  }
}

multi method set_b($x) {
  self.b = $x;
}
HERE_PM

$ cat T.pl HERE_PL
#!/usr/bin/env perl6

use v6;
use lib '.';
use T;
my $t = T.new;
say \$t.a = {$t.a};
say \$t.b = {$t.b};
say \$t.c = {$t.c.defined ?? $t.c !! 'undefined'};
$t.set_b(20);
$t.c = 'defined';
say \$t.a = {$t.a};
say \$t.b = {$t.b};
say \$t.c = {$t.c.defined ?? $t.c !! 'undefined'};
HERE_PM

$ perl6 T.pl
$t.a = 15
$t.b = 0
$t.c = undefined
$t.a = 15
$t.b = 20
$t.c = defined

Best,

-Tom

Re: Object Contruction

2015-03-18 Thread Tom Browder 
You are correct, Liz, but I was trying those pieces to demonstrate to
myself that all was available to me in the methods and all worked as I
expected.

It demos very roughly what I think I have to do to translate Geo::Ellipsoid
to Perl 6.  It's a WIP and I'm learning Perl 6 as I go.  The prog is a toy
and not otherwise useful.

Thanks.

BTW, will you or any other Perl 6 people be presenting at YAPC::NC?  I
don't see a speaking line-up yet.

Best,

-Tom

Re: Object Contruction

2015-03-18 Thread Elizabeth Mattijsen 
 On 18 Mar 2015, at 23:21, Tom Browder tom.brow...@gmail.com wrote:
 
 You are correct, Liz, but I was trying those pieces to demonstrate to myself 
 that all was available to me in the methods and all worked as I expected.
 
 It demos very roughly what I think I have to do to translate Geo::Ellipsoid 
 to Perl 6.  It's a WIP and I'm learning Perl 6 as I go.  The prog is a toy 
 and not otherwise useful.
 
 Thanks.
 
 BTW, will you or any other Perl 6 people be presenting at YAPC::NC?  I don't 
 see a speaking line-up yet.

YAPC::NC  ??  You mean YAPC::NA?

I will be there, but haven’t had any inspiration for a presentation just yet.




Liz

Re: Object Contruction

2015-03-18 Thread Elizabeth Mattijsen 
 On 18 Mar 2015, at 21:32, Tom Browder tom.brow...@gmail.com wrote:
 On Wed, Mar 18, 2015 at 11:32 AM, Tom Browder tom.brow...@gmail.com wrote:
 On Wed, Mar 18, 2015 at 7:22 AM, Moritz Lenz mor...@faui2k3.org wrote:
 ...
 http://doc.perl6.org/language/objects#Object_Construction lists at least two
 possible ways. Probably the most interesting one is BUILDALL with a
 callsame; see the last example (or example skeleton) in that section.
 
 For my purposes I think the BUILD is best.  The BUILDALL method seems
 to put me in limbo as far as the constructed object and using self.
 
 I made a simple class and a driver Perl script:
 
 $ cat T.pm HERE_PM
 class T;
 
 has $.a is rw;
 has $.b is rw;
 has $.c is rw;
 
 submethod BUILD(
 # set defaults here
 :$!a = 15,
 :$!b,

Why not set the default here?

  :$!b = $!a  10 ?? 1 !! 0;

 :$!c,
  ) {
  self.set_b;

Then you won’t need this.

 }
 
 multi method set_b {
  if (self.a  10) {
self.b = 1;
  }
  else {
self.b = 0;
  }
 }

Nor this.

 multi method set_b($x) {
  self.b = $x;
 }

Nor this.

 HERE_PM
 
 $ cat T.pl HERE_PL
 #!/usr/bin/env perl6
 
 use v6;
 use lib '.';
 use T;
 my $t = T.new;
 say \$t.a = {$t.a};
 say \$t.b = {$t.b};
 say \$t.c = {$t.c.defined ?? $t.c !! 'undefined'};
 $t.set_b(20);

This would then just be:

  $t.set(20);

 $t.c = 'defined';
 say \$t.a = {$t.a};
 say \$t.b = {$t.b};
 say \$t.c = {$t.c.defined ?? $t.c !! 'undefined'};
 HERE_PM
 
 $ perl6 T.pl
 $t.a = 15
 $t.b = 0
 $t.c = undefined
 $t.a = 15
 $t.b = 20
 $t.c = defined


Liz