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Re^7: Creating dispatch table with variable in function name

by AnomalousMonk (Bishop)
on Nov 23, 2017 at 03:52 UTC ( #1204103=note: print w/replies, xml ) Need Help??


in reply to Re^6: Creating dispatch table with variable in function name
in thread Creating dispatch table with variable in function name

So does the equivalent static dispatch table.

Hmm... I hadn't tested that. Ok, how about:

c:\@Work\Perl\monks>perl -MData::Dump -le "use warnings; use strict; ;; sub _x_foo { hiya(@_); } sub _x_bar { hiya(@_); } ;; my %disp = map { my $agent = qq{_x_$_}; $_ => __PACKAGE__->UNIVERSAL::can($agent) || die qq{dispatch via unknown agent '$agent'}; } qw(foo bar BAM) ; ::dd \%disp; ;; sub hiya { print 'hi from ', (caller(1))[3], qq{ (@_)}; } ;; $disp{foo}(); $disp{POW}(qw(x y z)); $disp{bar}(99, 88); " dispatch via unknown agent '_x_BAM' at -e line 1.
This throws both compile- and run-time exceptions, although I don't like the obscure wording of the run-time error message.

How about putting the whole thing into a lexically scoped package? This allows full control of the composition of the run-time error message, and makes the dispatch hash entirely private. It's also all ready to be moved off to its own module. I can't say I'm fond the  Dispatch::me('foo') invocation syntax, but putting this in its own module would give you some more syntax choices.

c:\@Work\Perl\monks>perl -MData::Dump -le "use warnings; use strict; ;; { package Dispatch; ;; sub _x_foo { hiya(@_); } sub _x_bar { hiya(@_); } ;; my %disp = map { my $agent = qq{_x_$_}; $_ => __PACKAGE__->UNIVERSAL::can($agent) || die qq{dispatch via unknown agent '$agent'}; } qw(foo bar BAM) ; ::dd \%disp; ;; sub me { my $tag = shift; ;; die qq{unknown dispatcher '$tag' used} unless exists $disp{$tag}; ;; return $disp{$tag}(@_); } ;; sub hiya { print 'hi from ', (caller(1))[3], qq{ (@_)}; } } ;; Dispatch::me('foo'); Dispatch::me('POW', qw(x y z)); Dispatch::me('bar', 99, 88); " dispatch via unknown agent '_x_BAM' at -e line 1.


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