Here is the difference, plus another way to write it.

my $conf_file= @_
creates the $conf_file scalar variable and sets it to the value of @_ in scalar context, which is... 1, hence the error message when your script tries to open the1 file.

my( $conf_file)= @_;
creates the scalar variable $conf_file and puts it in a list (as the first and only element of that list). Then it sets that list with @_, which means that the first element in that list ($conf_file) gets the first element of @_. Which works fine when called with just one element, but maybe not for the reasons you thought.

You could also have written
my $conf_file= shift;
which declares the scalar variable $conf_file and removes the first element from @_ and sets $conf_file with it.

Which leads me to a style question to my fellow monks: do you usually use
my( $arg1, $arg2)= @_;
or
my $arg1= shift;
my $arg2= shift; ?

The first option is more compact but the second one lets you check for extra (unwanted) arguments if you want.

I usually use the my( $arg1, $arg2)= @_; form, but maybe it's just lazyness...

In reply to Re: using 'my $var' vs. 'my($var)' by mirod
in thread using 'my $var' vs. 'my($var)' by decnartne

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