Subroutine redefined error that I can't figure out

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

My eval()s a code segment within a subroutine. The code it evals contains a subroutine, which I would think is completely local to the subroutine doing the eval. However the subroutine persists and I get a 'Subroutine redefined' warning whenever I call the eval more than once. See the code below. Main program is testeval.pl. It reads and evals code from testeval_code.pl

The main program = testeval.pl
##########################################
#!/usr/bin/perl -w

# call it twice to get the 'redfined' warning
&testeval;
&testeval;

sub testeval {
    # read a replaceable code segment from a 
    # file containing the evalsub subroutne
    my $code = read_replacable_code("testeval_code.pl");
    eval $code;
    if ($@) {
        print "error eval $@\n";
    }
 
    # call the sub defined in the eval'd code
    &evalsub;
}



sub read_replacable_code {
    my $fname = shift;
    $code = '';
    if (open (FCODE, $fname)) {
        while (my $line = <FCODE>) {
            $code .= $line;
        }
        close (FCODE);
    }
    return $code;
}


the replacable code segment - testeval_code.pl
##########################################

sub evalsub {
    print "evalsub\n";
}


results
##########################################
[root@mma-qa-be01 nick]# ./testeval.pl
evalsub
Subroutine evalsub redefined at (eval 2) line 2.
evalsub
[download]

Comment on Subroutine redefined error that I can't figure out Download Code

Replies are listed 'Best First'.
Re: Subroutine redefined error that I can't figure out by Corion (Patriarch) on Apr 11, 2008 at 14:04 UTC
Basically, subroutine names are global. Perl does not have locally nested subroutines. One possible way around it is to localize your changes to the symbol table: `local *evalsub; eval $code; evalsub();` [download] Another way is to avoid using named subroutines and use code references: `my $code = 'sub { print "evalsub" }'; my $coderef = eval $code; # Call our code $coderef->();` [download]	[reply] [d/l] [select]
Re^2: Subroutine redefined error that I can't figure out by nickm (Novice) on Apr 11, 2008 at 14:12 UTC
local *evalsub works great and is the most flexible for my purpuses. Thanks for the help!	[reply]
Re: Subroutine redefined error that I can't figure out by Anonymous Monk on Apr 11, 2008 at 14:05 UTC
subroutines are global, read perlsub	[reply]
Re: Subroutine redefined error that I can't figure out by apl (Monsignor) on Apr 11, 2008 at 14:13 UTC
I made the $code in read_replacable_code local to that subroutine, and everything ran fine.	[reply]