Gossamer Forum: General: Perl Programming: Precedence

May 30, 2003, 8:56 AM

Paul

Veteran (19537 posts)

May 30, 2003, 8:56 AM

Post #1 of 10

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Precedence

I could have sworn this code used to work...

Code:
my $href = do($path) or return $self->fatal("Oops: $!");

But now if do() returns false nothing happens. In order for the error to trigger I have to use:

Code:
my $href = do($path) || return $self->fatal("Oops: $!");

I'm guessing I could also write that as:

Code:
(my $href = do($path)) or return $self->fatal("Oops: $!");

May 30, 2003, 8:57 AM

Paul

Veteran (19537 posts)

May 30, 2003, 8:57 AM

Post #2 of 10

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Re: [Paul] Precedence In reply to

Mm that's a no for the third example Unsure

Jun 1, 2003, 4:48 PM

adrockjames

Novice (35 posts)

Jun 1, 2003, 4:48 PM

Post #3 of 10

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Re: [Paul] Precedence In reply to

1 and 3 are the same. (unless precedence has changed at all in versions > 5.6)

if do($path) returns 0 in both, the result should be the same, since my $href = do($path) will be 0 in the first example.

have you tested with 0 in place of do($path), or printed do($path) to STDOUT?

i'm curious to know what you found...

Jun 1, 2003, 5:08 PM

Paul

Veteran (19537 posts)

Jun 1, 2003, 5:08 PM

Post #4 of 10

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Re: [adrockjames] Precedence In reply to

Good idea. I'll try that out tommorrow. I always thought do(0 would return 0 or undef on failure but I guess the best way is to test.

Jun 1, 2003, 5:14 PM

Paul

Veteran (19537 posts)

Jun 1, 2003, 5:14 PM

Post #5 of 10

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Re: [adrockjames] Precedence In reply to

Quote:

[root@cypress cgi-bin]# perl -e "print defined(do('/path/to/nothing')) ? 'YES' : 'NO'"

NO[/code]
Surely that means the first example should work? :(

Last edited by:

Paul: Jun 1, 2003, 5:14 PM

Jun 2, 2003, 10:53 AM

Alex

Administrator (9387 posts)

Jun 2, 2003, 10:53 AM

Post #6 of 10

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Re: [Paul] Precedence In reply to

The first one does work:

Code:
[alex@penguin projects]$ perl -le 'my $href = do("/abc") or return $self->fatal("Oops: $!");' 
Can't call method "fatal" on an undefined value at -e line 1. 
[alex@penguin projects]$

(It tried to run ->fatal). Must be something wrong somewhere else (perhaps inside of fatal?)

Cheers,

Alex
--
Gossamer Threads Inc.

Jun 2, 2003, 10:59 AM

Paul

Veteran (19537 posts)

Jun 2, 2003, 10:59 AM

Post #7 of 10

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Re: [Alex] Precedence In reply to

Mmm that's weird, I've tried it a few times and it won't trigger. As soon as I change "or" to || it then triggers.

The fatal() method is:

Code:
sub fatal { 
#---------------------------------------------------------- 
# Generic error routine. Halts script execution. 
# Usage: $class->fatal($error, @vars); 

    my ($self, $error, @args) = @_; 
    my ($class, $file, $line) = caller; 

# Now grab the error message. 
    if (ref $error eq 'SCALAR') { $err_msg = $$error } 
    else { 
        my $errors = ref ${$class . '::ERRORS'} eq 'HASH' ? ${$class . '::ERRORS'} : {}; 
        if (exists $errors->{$error}) { 
            $err_msg = sprintf($errors->{$error}, @args); 
        } 
    } 

# Print the error with extra debugging if debugging is on. 
    print qq{Content-type: text/html\n\n}; 
    print qq{<font face="tahoma" size="2">An error occured:<br><br>}; 
    print qq{@{[qq{&nbsp;} x 10]}$class ($$): $err_msg<br><br>}; 
    print qq{Caller: $class in $file at line $line}; 
    print qq{</font>}; 
    exit 1; 
}