Beefy Boxes and Bandwidth Generously Provided by pair Networks
There's more than one way to do things
 
PerlMonks  

Re^3: Autovivification sucking the life out of me

by pg (Canon)
on Oct 14, 2005 at 06:54 UTC ( #500141=note: print w/replies, xml ) Need Help??


in reply to Re^2: Autovivification sucking the life out of me
in thread Autovivification sucking the life out of me

Update: My apologies! Forget what I have said, it was my observation was off, not yours. But it might be a better idea to demo your issue by using Data::Dumper.

use Data::Dumper; use strict; use warnings; my %foo = ( BAZ => 1 ); sub see_args { }; print Dumper(\%foo); see_args( @foo{qw(BAR BAZ)} ); print Dumper(\%foo);

It prints:

$VAR1 = { 'BAZ' => 1 }; $VAR1 = { 'BAZ' => 1, 'BAR' => undef };

Yes, autovivification is in working.

Your observation was off. In your original post, you were confused by the fact that the $ENV{TMPDIR} "appears" to have a value as you saw it through that sprintf. No, you didn't see the value of $ENV{TMPDIR}. Your sprintf printed a constant "<absent>", not the value of $ENV{TMPDIR}.</strick>

Replies are listed 'Best First'.
Re^4: Autovivification sucking the life out of me
by shenme (Priest) on Oct 14, 2005 at 07:11 UTC
    A simpler example perhaps:
    use strict; use warnings; my %foo = ( BAZ => 1 ); sub see_args { }; warn sprintf "at start: BAR '%s'\n", ! exists $foo{BAR} ? '<absent>' : ! defined $foo{BAR} ? '<und +ef>' : $foo{BAR}; # see_args( @foo{qw(BAR BAZ)} ); my @a = @foo{qw(BAR BAZ)}; warn sprintf "at end: BAR '%s'\n", ! exists $foo{BAR} ? '<absent>' : ! defined $foo{BAR} ? '<und +ef>' : $foo{BAR};

    Running this without the subroutine call, but rather the assignment to the array, results in output:

    at start: BAR '<absent>' at end: BAR '<absent>'
    That is, using the slice @foo{qw(BAR BAZ)} returns the values without modifying them.

    Commenting out the assignment and instead executing the subroutine call produces this output:

    at start: BAR '<absent>' at end: BAR '<undef>'
    Somehow using the slice in the call to the subroutine has modified the values in the slice, creating an undef value for the key 'BAR'. How?

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://500141]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others chilling in the Monastery: (2)
As of 2021-04-15 03:00 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found

    Notices?