NAME

Photonic::Iterator

VERSION

version 0.012

COPYRIGHT NOTICE

Photonic - A perl package for calculations on photonics and metamaterials.

Copyright (C) 1916 by W. Luis Mochán

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 1, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA

    mochan@fis.unam.mx

    Instituto de Ciencias Físicas, UNAM
    Apartado Postal 48-3
    62251 Cuernavaca, Morelos
    México

SYNOPSYS

     use Photonic::Iterator qw(iterator nextval);
     sub makeiterator {
         my $a=shift;
         my $n=0;
         my $it = iterator {
              return $a->[$n++];
         };
         return $it;
     }
     sub makebiterator { #blessed version
         my $a=shift;
         my $n=0;
         my $it=Photonic::Iterator->new(sub {
              return $a->[$n++];
         });
         return $it;
     }
     my @a=(1..100);
     my $it=makeiterator(\@a);
     my $bit=makebiterator(\@a);
     while(my $x=nextval($it)){
        #do something with $x
     }
     while(my $x=$bit->nextval){
        #do something with $x
     }

DESCRIPTION

Facilitate the creation of iterators. Iterators are objects that produce data items, one at a time, until depleted. They are implemented as functions (closures) that have state (implemented as lexical variables) to know which is the next item. The example above creates an iterator for walking over the elements of an array reference. The method or function nextval produces the next element if available or undef when there is no more data. Used in Photonic to iterate over Haydock states without caring whether they are stored in an array or in an external file.

EXPORTABLE FUNCTIONS

iterator
    my $i=iterator {...}

creates an iterator from the function {...}

new
   my $it=Photonic::Iterator->new(sub {...});

creates a blessed iterator from the function sub {...}

nextval
   my $x=nextval($i)
   my $x=$i->nextval

returns the next value from iterator $i. The second form works for blessed iterators, so you don't have to import the function nextval.