execute function with name passed as string parameter

rgcosma has asked for the wisdom of the Perl Monks concerning the following question:

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Re: execute function with name passed as string parameter by Utilitarian (Vicar) on May 05, 2011 at 10:09 UTC
You are not assigning a code_ref in your hash, but rather the out put of your routines, this causes them to run on assignment. `perl -e '$choice="1"; %hash=( 0 => one, 1 => two ); sub one {print "on +e\n"}; sub two {print "two\n"} &{$hash{$choice}}' two` [download] `print "Good ",qw(night morning afternoon evening)[(localtime)[2]/6]," fellow monks."`	[reply] [d/l] [select]
Re: execute function with name passed as string parameter by shmem (Chancellor) on May 05, 2011 at 12:05 UTC
What the other monks said, but TIMTOWTDI. You can also store subroutine references in your hash and execute them. `perl -le '$choice='1'; %hash=( '0' => \&one, '1' => \&two ); $hash{$ch +oice}->(); sub one {print "one"}; sub two {print "two"}'` [download] You could also call the subroutine reference via `&{$hash{choice}}` - but be aware that there's a subtle difference: `$\="\n"; # output record separator $choice='1'; %hash=( '0' => \&one, '1' => \&two ); @_ = "fish"; $hash{$choice}->(); &{$hash{$choice}}; one; &one; sub one { print "one", @_ } sub two { print "two", @_ } __END__ two twofish one onefish` [download] That is, `&sub, &$sub, &{gimme_a_subref()}` and so on - without parens - pass the current `@_` to the called subroutine. Of course, `&{$hash{$choice}}()` - with parens - passes an empty list.	[reply] [d/l] [select]
Re^2: execute function with name passed as string parameter by rgcosma (Beadle) on May 05, 2011 at 14:30 UTC
OK, so it was a syntax misunderstanding, thank you all.	[reply]
Re: execute function with name passed as string parameter by chakreey (Acolyte) on May 05, 2011 at 10:45 UTC
`&` symbol in `&one, &two` is meant for calling subroutines. If your intention is not to call subroutines, but just assign subroutine names, then, use `'one', 'two'` For calling subroutine, use `&{$hash{$choice}}` `perl -e '$choice='1'; %hash=( '0' => 'one', '1' => 'two');&{$hash{$choice}}; sub one {print "one"};sub two {print "two"}'`	[reply] [d/l] [select]
Re: execute function with name passed as string parameter by NetWallah (Canon) on May 06, 2011 at 05:02 UTC
Simpler calling convention for using a variable as a sub-name - use parens: `perl -e '$choice="1"; %hash=( 0 => one, 1 => two ); sub one {print "on +e\n"}; sub two {print "two\n"};$hash{1}()'` [download] prints : "two" Syntactic sugar causes cancer of the semicolon. --Alan Perlis	[reply] [d/l]