The document discusses different types of variables in Perl, including global ('our'), lexical ('my'), state, and local variables. It explains the scope and functionality of each type, providing examples to illustrate their usage. The presentation concludes with a Q&A session and thanks the audience.

1. Our local state, my, my

2. Your speaker for the evening
● Sawyer X
● Github.com/xsawyerx
● Blogs.perl.org/users/sawyer_x
● #dancer @ irc.perl.org

3. Our local state, my, my

4. our, local, state, my, my

5. Perl variables, the easy part
● our is global
● my is lexical

6. Easy part done!

7. What's a global variable?
● Perl code is divided to namespaces
● We use 'package' to declare them
● 'main' is the default namespace
● Globals are package variables
● Variables relating to that namespace
● (not the same as “superglobals”)
● (globals are saved in typeglobs)

8. Global variables, examples
● our $name; # $main::name
● package My::Package;
our $name; # $My::Package::name
● say $Moose::VERSION;

9. Globals: done!

10. What's a lexical variable?
● Scoped variables
● Variables that exist only in a scope!
● Available scopes: block, file, eval
● We define lexical variables with 'my'
● (they are saved in a lex pad)

11. Lexical variables, examples
● { my $exists_only_here }
● { my $outer; { my $inner } }
● foreach my $name (@names) {
say $name; # okay
}
say $name; # error

12. Lexical variables, pop quiz!
package Example;
my $exvar = 30;
package main;
say $exvar;
● Error or no error?

13. Lexical variables, pop quiz!
● No error!
● my is lexical
● package is a namespace, not a scope
● The scope here is the “file scope”
● Here is the correct way to do it:
{ package Example; my $exvar; }

14. Lexicals: done!

15. What's a state variable?
● Lexical variables with a twist!
● They don't get reinitialized
● sub inc {
state $myvar = 0; # default value
return ++$myvar;
}
say inc($_) for 1 .. 10;

16. States: Done!

17. What's a local variable?
● Something that confuses people
● But very simple, actually
● Localizes an already existing variable
● Used to temporarily override
variables instead of creating new ones
● Useful with superglobals
● Prevents fscking them up

18. Local variables, examples
● Slurping file content:
use autodie;
open my $fh, '<', $filename;
my $content = do { local $/; <$fh> };
close $fh;

19. Local variables, examples
● No output buffering for this scope:
local $| = 1;
● Disabling warnings for a scope:
{
local $^W = 0;
# do something that would warn
}

20. Locals: done!

21. Questions?

22. Thank you!
(yes, you can finally go home)