what exactly am I passing to "genPicker"? A file handle?

You answered your own question :) Yes, its a file handle. *DATA is a (pseudo)filehandle that allows access the 'file' after __DATA__.

So,if you had your input in a file called numbs.dat, you do this:

...
open my $fh, '<', 'numbs.dat' or die $!;

my $pick = genPicker( $fh ); ## Reads the file and generates a picker 
+subroutine according to its contents.

close $fh;

### use $pick->() each time you want a new random number.
[download]

Hi BrowserUk,

I'm still running into trouble. Here is my code:

#!/usr/bin/perl -w
use strict;
use Data::Dump qw[ pp ];

open my $fh, '<', 'numbs.dat' or die $!;

my $pick = genPicker( $fh ); ## Reads the file and generates a picker

sub genPicker {
    my $fh = shift;
    my( @vals, @odds ); ( $vals[ @vals ], $odds[ @odds ] ) = split( ' 
+' ) for <$fh>;

    ## Sort if not sorted
    my @order = sort{ $odds[ $a ] <=> $odds[ $b ] } 0 .. $#odds;
    @odds = @odds[ @order ];
    @vals = @vals[ @order ];

    ## Calculate and accumulate break points
    my $t = 0; $t += $_ for @odds;
    $_ /= $t for @odds;
    $odds[ $_ + 1 ] += $odds[ $_ ] for 0 .. $#odds - 1;

    ## Generate a subroutine to do the picking
    return sub {
        my $r = rand();
        $r < $odds[ $_ ] and return $vals[ $_ ] for 0 .. $#odds;
    };
}

close $fh;
[download]

Here is my numbs.dat file (I changed the numbers to simplify things):

A 0.0001
B 0.0004
C 0.0008
[download]

For what it's worth, there is a new line after each row except the last, and each letter is separated from the corresponding number by a single space. I think something is going wrong with my split, because if I pause the script and look into the variables, my @odds array has three slots, each of which is undefined, whereas my @vals array has three slots, each of which contains a letter, a space, a number and then for the first two slots a new line character.

Do you see what's wrong?

Best wishes,

Eric

Do you see what's wrong?

Maybe. When you C&P'd the code, you did so without using [download] link first.

Because of that, one of the longer lines has been (moronically and pointlessly) "wrapped" by the PM website, and extra characters insertewd. Hence the line that should be:

    my( @vals, @odds ); ( $vals[ @vals ], $odds[ @odds ] ) = split( ' 
+' ) for <$fh>;
[download]

Has been autofcuked into:

    my( @vals, @odds ); ( $vals[ @vals ], $odds[ @odds ] ) = split( ' 
+' ) for <$fh>;
[download]

Change that back and see how you get on. (Did you really get no warnings or errors?)

---

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority". I'm with torvalds on this

In the absence of evidence, opinion is indistinguishable from prejudice. Agile (and TDD) debunked