Re^2: Function reference undef when extract from hash?

I used strict and warning.

And the call of the build_sth('set_to_flag') in another function which is called in the main per script:

(continue with previous code)
sub somecall{
build_sth('set_to_flag')
}

somecall();
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I have checked the previous version where I got trapped. I get the code fail when I move the hash outside of function:

my %Op = (
        set_to_flag => \&write_flag,
        set_tree => \&write_sets,
        default => \&do_nothing
    );
sub build_sth {
    my ($op_code) = @_;
    
    my $op_exec = $Op{$op_code} ;
    if( defined $op_exec ){
        $op_exec->();
    }else{
        print "Oops\n";
    }

}
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why the code fail in this case?

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Re^3: Function reference undef when extract from hash? by ikegami (Patriarch) on Mar 04, 2008 at 00:55 UTC
why the code fail in this case? The only possibly reason is if `build_sth('set_to_flag')` is called before `my %Op = ( ... );` is executed. Otherwise, it doesn't fail. `sub write_flag { print "write_flag\n"; } sub set_tree { print "set_tree\n"; } sub do_nothing { print "do_nothing\n"; } ... code you provided ... build_sth('set_to_flag'); # Prints write_flag` [download]	[reply] [d/l] [select]