Somehow the lexical variable in the do block gets attached to the upper scope. As shown with the test below: 

use 5.014;
use warnings;

package Temp;
use parent 'File::Temp';

sub new { 
    my $self = shift;
    $self-> SUPER::new( DIR => '.' )
}

sub DESTROY {
    my $self = shift;
    say "Destruction during ", ${^GLOBAL_PHASE};
    $self-> SUPER::DESTROY
}

package main;
use File::Copy;

sub foo { my $h = Temp-> new }

die unless -f 'x';      # this file must exist

{
  copy 'x', my $fn1 = Temp-> new-> filename                or die;
  copy 'x', my $fn2 = do { Temp-> new }-> filename         or die;
  copy 'x', my $fn3 = do { my $h = Temp-> new }-> filename or die;
  copy 'x', my $fn4 = foo-> filename                       or die;

  say 1 if -f $fn1;
  say 2 if -f $fn2;
  say 3 if -f $fn3;
  say 4 if -f $fn4;
  
  say "End of scope";

}
say "End of file";

__END__

Destruction during RUN
Destruction during RUN
Destruction during RUN
3
End of scope
Destruction during RUN
End of file

[download]
This works however: 
copy 'x', my $fn3 = do { { my $h = Temp-> new } }-> filename or die;

[download]
because the extra block creates a lexical scope inside the do block.

The documentation for do states that it does not work as a loop, when all other blocks (even bare one, without the for or while keyword) do, (which means next and last and redo don't work on do blocks). So somehow do blocks aren't blocks either? What's weird is that there is a "local" scope bound to do, so 

$_ = "Hi"; 
do { local $_ = "Hello" };
print

[download]
does print; "Hi" as expected...

In reply to Re: File::Temp survival and scope created by "do" by Eily
in thread File::Temp survival and scope created by "do" by vr

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