Re: what is the return value

To proove that the code does not do what's stated here, try this:

Create a file "a" containing the line "from a"
Create a file "b" containing the line "from b"

Change the code to this:

use strict;
use warnings;

open my $in, '<', "a";
print firstline("b");

sub firstline {
  open (my $in, shift) && return scalar <$in>;
  # no close() required
}
[download]

If the descriptions here were right, you should get "from b" but you will get "from a".

The reason is that "<$in>" is referring to the outer $in.

s$$([},&%#}/&/]+}%&{})*;#$&&s&&$^X.($'^"%]=\&(|?*{%
+.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e

Comment on Re: what is the return value Select or Download Code

Replies are listed 'Best First'.
Re^2: what is the return value by MidLifeXis (Monsignor) on Jul 09, 2013 at 14:42 UTC
And this works 'as expected', I think... `use strict; use warnings; open my $in, '<', "a"; print firstline("b"); sub firstline { my $retval = open (my $in, shift); $retval && return scalar <$in>; # no close() required }` [download] --MidLifeXis	[reply] [d/l]
Re^2: what is the return value by fishmonger (Chaplain) on Jul 09, 2013 at 14:42 UTC
You are correct, and there are several ways the OP could fix that problem. The first thing that I thought of would be to simply declare $in prior to the open call. The second was to use the ternary operator. `return open ($in, '<', shift ) ? scalar <$in> : undef; # using undef may or may not be desirable in this case`	[reply] [d/l]
Re^2: what is the return value by ww (Archbishop) on Jul 09, 2013 at 15:14 UTC
Whereas, and TIMTOWTDI: `#!/usr/bin/perl use strict; use warnings; use 5.016; # Modified from parent and MidLifeXis' 1043331 open my $in, '<', "a.txt"; print firstline("b.txt"); sub firstline { say "at_: @_"; my $file = shift; my $retval = open (my $FH, '<', $file ); $retval && return scalar <$FH>; # no close() required }` [download] prints: `at_: b.txt from b` [download] If you didn't program your executable by toggling in binary, it wasn't really programming!	[reply] [d/l] [select]