Iterator Example

• This is a typical search-and-locate example (that is, it is a toy example)

• Search a text file looking for matching lines

• Obvious way:

 sub locate {
 my ($key, $file) = @_;
 local *FH;
 open FH, $file or return;
 my @result;
 while (<FH>) {
 push @result, $_ if index($_, $key) >= 0;
 }
 @result;
 }

• Maybe we spent a lot of time locating all the matching lines

• Maybe we only needed a couple

• Maybe the file was very big

• Maybe several different parts of the program need to look for different things