Package Basics

A package gives subroutines a namespace so names can be organized.
package A package is a namespace for Perl symbols such as subroutine names.
                            name
                            name = "Perl" (default)name = "Mira"name = "Ada"
                        

                            package_basics.pl
                        
Replay: real traced execution (multi-file project)

                            use strict;
use warnings;

package Greeter;

sub greet {
    my ($name) = @_;
    return "Hello, $name";
}

package main;

my $name = "Perl";
my $message = Greeter::greet($name);

print "name=$name\n";
print "message=$message\n";
use strict;
use warnings;

package Greeter;

sub greet {
    my ($name) = @_;
    return "Hello, $name";
}

package main;

my $name = "Mira";
my $message = Greeter::greet($name);

print "name=$name\n";
print "message=$message\n";
use strict;
use warnings;

package Greeter;

sub greet {
    my ($name) = @_;
    return "Hello, $name";
}

package main;

my $name = "Ada";
my $message = Greeter::greet($name);

print "name=$name\n";
print "message=$message\n";

                        
1$name ← Perl⋯13my $name→ Perl = "Perl"; #@name="Mira", "Ada"14my $message = Greeter::greet($namePerl);⋯
2$name ← Perl⋯6sub greet {7    my ($name→ Perl) = @_;8    return "Hello, $namePerl";9}⋯
3$message ← Hello, Perl⋯13my $name = "Perl"; #@name="Mira", "Ada"14my $message→ Hello, Perl = Greeter::greet($namePerl);1516print "name=$namePerl\n";17print "message=$messageHello, Perl\n";⋯outputname=Perl
message=Hello, Perl
1$name ← Mira⋯13my $name→ Mira = "Mira";14my $message = Greeter::greet($nameMira);⋯
2$name ← Mira⋯6sub greet {7    my ($name→ Mira) = @_;8    return "Hello, $nameMira";9}⋯
3$message ← Hello, Mira⋯13my $name = "Mira";14my $message→ Hello, Mira = Greeter::greet($nameMira);1516print "name=$nameMira\n";17print "message=$messageHello, Mira\n";⋯outputname=Mira
message=Hello, Mira
1$name ← Ada⋯13my $name→ Ada = "Ada";14my $message = Greeter::greet($nameAda);⋯
2$name ← Ada⋯6sub greet {7    my ($name→ Ada) = @_;8    return "Hello, $nameAda";9}⋯
3$message ← Hello, Ada⋯13my $name = "Ada";14my $message→ Hello, Ada = Greeter::greet($nameAda);1516print "name=$nameAda\n";17print "message=$messageHello, Ada\n";⋯outputname=Ada
message=Hello, Ada