State Records

Keep related state as named scalar values.
state-records State is easier to reason about when each field has a clear name.
                            level
                            level = 2 (default)level = 1level = 5
                        

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

                            use strict;
use warnings;

package Badge;

sub summary {
    my ($name, $level) = @_;
    return "$name:$level";
}

package main;

my $level = 2;
my $name = "Rin";
my $summary = Badge::summary($name, $level);

print "name=$name\n";
print "level=$level\n";
print "summary=$summary\n";
use strict;
use warnings;

package Badge;

sub summary {
    my ($name, $level) = @_;
    return "$name:$level";
}

package main;

my $level = 1;
my $name = "Rin";
my $summary = Badge::summary($name, $level);

print "name=$name\n";
print "level=$level\n";
print "summary=$summary\n";
use strict;
use warnings;

package Badge;

sub summary {
    my ($name, $level) = @_;
    return "$name:$level";
}

package main;

my $level = 5;
my $name = "Rin";
my $summary = Badge::summary($name, $level);

print "name=$name\n";
print "level=$level\n";
print "summary=$summary\n";

                        
1$level ← 2, $name ← Rin⋯13my $level→ 2 = 2; #@level=1, 514my $name→ Rin = "Rin";15my $summary = Badge::summary($nameRin, $level2);⋯
2$name ← Rin, $level ← 2⋯6sub summary {7    my ($name→ Rin, $level→ 2) = @_;8    return "$nameRin:$level2";9}⋯
3$summary ← Rin:2⋯14my $name = "Rin";15my $summary→ Rin:2 = Badge::summary($nameRin, $level2);1617print "name=$nameRin\n";18print "level=$level2\n";19print "summary=$summaryRin:2\n";⋯outputname=Rin
level=2
summary=Rin:2
1$level ← 1, $name ← Rin⋯13my $level→ 1 = 1;14my $name→ Rin = "Rin";15my $summary = Badge::summary($nameRin, $level1);⋯
2$name ← Rin, $level ← 1⋯6sub summary {7    my ($name→ Rin, $level→ 1) = @_;8    return "$nameRin:$level1";9}⋯
3$summary ← Rin:1⋯14my $name = "Rin";15my $summary→ Rin:1 = Badge::summary($nameRin, $level1);1617print "name=$nameRin\n";18print "level=$level1\n";19print "summary=$summaryRin:1\n";⋯outputname=Rin
level=1
summary=Rin:1
1$level ← 5, $name ← Rin⋯13my $level→ 5 = 5;14my $name→ Rin = "Rin";15my $summary = Badge::summary($nameRin, $level5);⋯
2$name ← Rin, $level ← 5⋯6sub summary {7    my ($name→ Rin, $level→ 5) = @_;8    return "$nameRin:$level5";9}⋯
3$summary ← Rin:5⋯14my $name = "Rin";15my $summary→ Rin:5 = Badge::summary($nameRin, $level5);1617print "name=$nameRin\n";18print "level=$level5\n";19print "summary=$summaryRin:5\n";⋯outputname=Rin
level=5
summary=Rin:5