Command-Line Program Patterns

Argument Lists

Model a command argument list with fixed local values.

argument-lists Command-line programs receive a list of words. In examples, a local list can show the same indexing and counting ideas without depending on the process that started the program.

Argument Lists

command
argv_simulation.pl
Replay: real traced execution (multi-file project)
use strict;
use warnings;

my $command = "build";
my $argument_count = 1;
my $summary = "command:$command";

print "count=$argument_count\n";
print "command=$command\n";
print "summary=$summary\n";

use strict;
use warnings;

my $command = "test";
my $argument_count = 1;
my $summary = "command:$command";

print "count=$argument_count\n";
print "command=$command\n";
print "summary=$summary\n";

use strict;
use warnings;

my $command = "help";
my $argument_count = 1;
my $summary = "command:$command";

print "count=$argument_count\n";
print "command=$command\n";
print "summary=$summary\n";

  1. $command ← build, $argument_count ← 1, $summary ← command:build

    4my $command→ build = "build"; #@command="test", "help"5my $argument_count→ 1 = 1;6my $summary→ command:build = "command:$commandbuild";78print "count=$argument_count1\n";9print "command=$commandbuild\n";10print "summary=$summarycommand:build\n";
    outputcount=1
command=build
summary=command:build

  1. $command ← test, $argument_count ← 1, $summary ← command:test

    4my $command→ test = "test";5my $argument_count→ 1 = 1;6my $summary→ command:test = "command:$commandtest";78print "count=$argument_count1\n";9print "command=$commandtest\n";10print "summary=$summarycommand:test\n";
    outputcount=1
command=test
summary=command:test

  1. $command ← help, $argument_count ← 1, $summary ← command:help

    4my $command→ help = "help";5my $argument_count→ 1 = 1;6my $summary→ command:help = "command:$commandhelp";78print "count=$argument_count1\n";9print "command=$commandhelp\n";10print "summary=$summarycommand:help\n";
    outputcount=1
command=help
summary=command:help