Yet Another syntactic variation would be something like: 

Win8 Strawberry 5.8.9.5 (32)  Sun 11/22/2020  3:11:34
C:\@Work\Perl\monks
>perl -l
use strict;
use warnings;

BEGIN {
    my %ops = (
        ADD_DATA    => [ qw(add    1) ],
        REMOVE_DATA => [ qw(remove 2) ],
        );
    sub valid (*) { return exists $ops{$_[0]}; }
    sub modes (*) {
        return valid($_[0]) ? [ @{ $ops{$_[0]} } ] : die "bad '$_[0]'"
+;
        }
    }

print 42    + modes(ADD_DATA)     ->[1];
print 'foo' . modes('REMOVE_DATA')->[0];

print 'invalid' if not valid(yyy);
print modes('xxx');
^Z
43
fooremove
invalid
bad 'xxx' at - line 11.

[download]

If you don't like arrow notation and prefer something like (...)[n], then: 

Win8 Strawberry 5.8.9.5 (32)  Sun 11/22/2020  3:14:57
C:\@Work\Perl\monks
>perl -l
use strict;
use warnings;

BEGIN {
    my %ops = (
        ADD_DATA    => [ qw(add    1) ],
        REMOVE_DATA => [ qw(remove 2) ],
        );
    sub valid (*) { return exists $ops{$_[0]}; }
    sub modes (*) {
        return valid($_[0]) ? @{ $ops{$_[0]} } : die "bad '$_[0]'";
        }
    }

print 42    + (modes ADD_DATA)     [1];
print 'foo' . (modes 'REMOVE_DATA')[0];

print 'invalid' if not valid yyy;
print modes 'xxx';
^Z
43
fooremove
invalid
bad 'xxx' at - line 11.

[download]

In either case, the data in %ops is absolutely immutable.

Give a man a fish:  <%-{-{-{-<

In reply to Re: Multi-dimensional constants by AnomalousMonk
in thread Multi-dimensional constants by Ionic

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