Re: Call subroutine by reference ?

The canonical solution to this issue is to use a "Dispatch table".

This is typically a hash whose keys are the text that is used to identify which sub to call, and the value is a reference to the sub.

my %Dispach_table = (
    UNO => \&Process_One,
    DOS => \&Process_Two,
    TRES => sub { print "This is an example of an in-line subref\n"},
);

sub Process_One{ #whatever
 }

sub Process_Two{ # Some code
}

my $var = "DOS";
# Invoke the dispatch (after verifying it exists)
$Dispatch_table{ $var } or die "ERROR: attempt to dispatch non-existin
+g entry: '$val'";
$Dispatch_table{ $var } -> ( #Parameters, if any
   ); # Here is where the routine gets called.
[download]

Update: Added check for "existence" as recommended by sundialsvc4 (++), below. (Also fixed text typo).

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Comment on Re: Call subroutine by reference ? Download Code

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Re^2: Call subroutine by reference ? by locked_user sundialsvc4 (Abbot) on May 31, 2013 at 10:48 UTC
Yes, and to clarify with-regard-to my previous post, there is no conflict between the two ideas ... they are quite-ordinarily used together, as Perl applications are quite-ordinarily built as systems of packages instead of monolithic and repetitive individual scripts. If you `use` a package, the `sub`s in them are (ordinarily ...) visible, both as `subroutine_name` and, if necessary, as `package_name::subroutine_name`. You can build code-references freely, as shown, because everything comes-together in memory (just...) before execution of the whole thing begins. The dispatch-table idea obviously is clearer and more-expandable than my `if..elsif..` structure, which was merely used here for clarity. n.b.: In actual practice, the `exists()` function should be used to verify that the key being sought actually does exist in the table, before attempting the call. e.g. `die "horribly" unless exists($dispatch_table->{$key});` ... so that the program will react graciously, or at-least die on its own terms instead of puking with “can't use 'undef' as a code reference” or what-not.
Re^2: Call subroutine by reference ? by JockoHelios (Scribe) on May 31, 2013 at 17:09 UTC
The Dispatch Table appeals to the Organization-OCD side of my brain :) I might end up with more than one main script, depending on the modifications I make to the analysis subroutines due to some variations on data content. So I'll need to pay more attention than usual to the code variations. Fortunately, I like that kind of project ;) Dyslexics Untie !!!	[reply]