$v = shift OR$_[0] on a filehandle, whats teh difereence

[Eduard W. Lohmann]

Hello. I write this little thing to help me log from several instances of
the same class in apache, mod_perl. But I can't figure one thing out.


package Logger;
require Carp;

# Write the message to the file pointed to by $fh with the time prepended
# and the place appended
sub log_ {
my $fh = shift;
print( $fh scalar(localtime()), ': ', Carp::shortmess("@_") );
};


Now this works fine, but if I replace this with:

sub log_ {
print( $_[0] scalar(localtime()), ': ', Carp::shortmess("@_") );
};

I get print on unopened filehandle. I can't seem figure out why.



# Turn array into a nice string, like (1, 2, 3) and log it
sub log_ARRAY {
log_($_[0], '('.join(', ', @{$_[1]}).')');
};

# Turn hash into a nice string, like { 1 => 'one', 2 => 'two' } and log it
sub log_HASH {
log_($_[0],'{ '.join(', ', map("$_ => ".$_[1]{$_},sort keys %{$_[1]})).' }');
};

# Treat anything else as a string and log it
sub AUTOLOAD {
goto &log_ if $AUTOLOAD =~ /^log_/;
};

# Logger::method('command', 'filename')
# Open 'filename' and create a sub in the callers package named 'command'
# that logs to it, nicely formatted.
sub method {
open(my $fh, ">> $_[1]") or $fh = \*STRERR;
*{ caller().'::'.$_[0]} = sub {
&{'log_'.ref($_) }($fh, $_) foreach (@_);
};
};

1;

 

[nobull]

sub log_ {
my $fh = shift;
print( $fh scalar(localtime()), ': ', Carp::shortmess("@_") );
};

Now this works fine, but if I replace this with:

sub log_ {
print( $_[0] scalar(localtime()), ': ', Carp::shortmess("@_") );
};

I get print on unopened filehandle. I can't seem figure out why.

perldoc -f print

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