On Sat, Jun 26, 2010 at 6:46 PM, David Mertens <[email protected]> wrote:
>
>
> On Sat, Jun 26, 2010 at 6:18 PM, P Kishor <[email protected]> wrote:
>>
>> On Sat, Jun 26, 2010 at 6:08 PM, David Mertens <[email protected]>
>> wrote:
>> > On Sat, Jun 26, 2010 at 3:47 PM, P Kishor <[email protected]> wrote:
>> >>
>> >> <snip>
>> >> On a related note... if I have my own function
>> >>
>> >> sub foo {
>> >> my ($a, $b, $c, $piddle) = @_;
>> >> do something to every element in $piddle based on $a, $b, $c
>> >> }
>> >>
>> >> I want to invoke it as a method call on my piddle $p, like so
>> >>
>> >> $p->foo($a, $b, $c)
>> >>
>> >> How do I construct that?
>> >
>> > This is question about writing object-oriented Perl. This is a whole new
>> > can
>> > of worms, but here are the basics.
>> >
>> > First, the method must take the piddle as its first argument. Second,
>> > the
>> > subroutine must be defined in the PDL package. Using these two ideas,
>> > you
>> > would instead have this:
>> >
>> > sub PDL::foo {
>> > my ($piddle, $a, $b, $c) = @_;
>> > # do something here
>> > }
>> >
>> > Defining the cod as such will allow you to write this code:
>> >
>> > @results = $piddle->foo($a, $b, $c);
>> >
>> > You may want foo to be both a function and a method. That is, you may
>> > want
>> >
>> > foo($piddle, $a, $b, $c)
>> >
>> > and
>> >
>> > $piddle->foo($a, $b, $c)
>>
>> Thanks David. This is exactly what I wanted to know. I know how to
>> create an Perl class and write OO code, but I wasn't sure if
>> PDL-wizards had already provide some funky shortcut for doing so.
>>
>> As it is, PDL continues to blow my mind. I frankly don't understand
>> why PDL is not a part of core Perl (besides being a pain-in-ass to
>> install), as I can't really imagine working with normal arrays ever
>> again, if I can help it.
>>
>> Anyway, yes, now that I know that I have to write the OO code myself,
>> but once I write my method, PDL will automatically apply it to every
>> element in my piddle, that is do-able magic!
>
> No no no! I misunderstood you. You were asking how to write a function that
> would automatically thread. That is not trivial. At the moment we don't have
> a way to auto-thread a Perl function. The only way to make a Perl function
> 'threadable' is to make sure of all its operations use threaded functions.
> To write a (PDL-)threaded function, you have to use PDL::PP.
>
> Sorry for the confusion.
>
Not really. Consider the following
perldl> $a = sequence 5
perldl> p $a
[0 1 2 3 4]
perldl> $b = sub { if ( $_[1] eq 'two' ) { return $_[0] * 2 } else {
return $_[0] * 5 } }
perldl> $c = $a->$b
perldl> p $c
[0 5 10 15 20]
perldl> $d = $a->$b('two')
perldl> p $d
[0 2 4 6 8]
perldl>
Maybe I misstated my own question earlier, but the above is exactly
what I want, and it seems to work well.
Puneet.
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