I think a dispatch table will rapidly become unwieldy if you need to consider all possible function call combinations of A, B, C, D and E. Assuming A must always be called first, and C must be called between B and D (if present), and so on, you are looking at the power set of A .. E. And the size of the power set of a set increases exponentially.

Here's all the different ways you can call functions A to E:

perl -MData::PowerSet -le 'my $p = Data::PowerSet->new(qw(A B C D E));
+ print "@$_" while $_= $p->next'
# produces :
A B C D E
B C D E
A C D E
C D E
A B D E
B D E
A D E
D E
A B C E
B C E
A C E
C E
A B E
B E
A E
E
A B C D
B C D
A C D
C D
A B D
B D
A D
D
A B C
B C
A C
C
A B
B
A

[download]

Add three more function and the size of your dispatch table grows to 256 entries... and it gets much worse if you can call any of A to E in any order.

I think it would be much better to just split your 'ABC' input into separate characters, and use a simple dispatch to deal with the five (or more) elementary cases:

my %dispatch = (
    A => \&func_a,
    B => \&func_b,
    C => \&func_c,
    D => \&func_d,
    E => \&func_e,
);
for my $token (split //, $func_com) {
    push @all_res, [$dispatch{$token}->(@some_val)];
}

[download]

This way it is as trivial to deal with 'ABC', 'AD', 'BCE' as it is to deal with 'AABD' or 'BEAD'.

• another intruder with the mooring in the heart of the Perl

In reply to Re: Howto avoid large hard-coded else-if function calls by grinder
in thread Howto avoid large hard-coded else-if function calls by neversaint

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