about_loops.pl

#!/usr/bin/perl
=pod
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=cut

package Perl::Koans::Loops;
use warnings;

use lib './lib';
use Perl::Koans;

################
# your code goes below this line

sub about_for {
    # about_for()
    
    # TODO write an explicit fencepost issue
    for (my $i = 0; $i < 10; $i++) {
        
        is ($i, __, 'a very common form of a for loop, incrementing a named variable from 0 to 9');
        
        last;
    }
    
    for (1..10) {
        
        is ($_, __, 'a common form of a for loop, incrementing the default variable from 1 to 10');
        
        last;
    }
    
    for (my $j = 10; $j > 0; $j--) {
        
        is ($j, __, 'a common form of a for loop, decrementing a named variable from 10 to 0');
        
        last;
    }
    
    for (reverse 1..10) {
        # for student: why doesn't 10..1 ?
        
        is ($_, __, 'an uncommon form of a for loop, decrementing the default variable from 10 to 1');
        
        last;
    }
    
    # now with predefined/complex variables
    my @array = ('a', 'b', 'c', 1, 2, 3, 'fizzbang');
    my %hash  = (
        foo => 1,
        bar => 2,
        baz => 3,
    );
    
	# foreach is a synonm for 'for' in list context
    for (@array) {
        
        is ($_, __, 'iterating the elements of an array');
        
        last;
    }
    
    for (my $i = 0; $i < $#array; $i++) {
        
        is (__, 'a', 'incrementing an iterator, using it to refer to array indicies'); # TODO rewrite this hint
        
        last;
    }
    

    # TODO need to talk about how perl doesn't do many in place changes (and the caveats to that--chomp/chop)
    for my $element (sort @array) {
        
        is ($element, __, 'sort() will return an array ordered in ASCIIbetical order');
        
        last;
    }
    
    for my $element (reverse @array) {
        
        is ($element, __, 'reverse() will return its operant in reverse order');
        
        last;
    }
    
    for my $element (reverse sort @array) {
        
        is ($element, __, 'reverse()ing a sort() will return its operant in reverse ASCIIbetical order');
        
        last;
    }

    for my $key (sort keys %hash) {
        # TODO: clarify comment below?
        # using sort here because the hashing order is unpredictable
        
        is ($key, __, 'hash keys are often sorted before they are iterated');
        
        
        last;
    }
    
    for my $value (sort values %hash) {
        
        is ($value, __, "this is less common, but sometimes you don't actually care about the keys themselves");
        
        last;
    }
    
    
    fail('last, next, redo, continue need coverage');
    
    
    return (Perl::Koans::get_return_code()); 
}

sub about_while {
    # about_while() - while loops execute as long as their sentinel test is 'true'
    
    my %hash = (
        fizz => 'bang',
    );
    
    while (my ($key, $value) = sort each %hash) {
        # each pulls ($key, $value) pairs from a hash
        
        is ($key,   __, 'each() returns a key/value pair from a hash -- part key');
        is ($value, __, 'each() returns a key/value pair from a hash -- part value');
        
        last;
    }
    
    while (1) {
        
        is (1, __, 'while(1) is used in place of "while(true)", runs until last() is called');
        
        last;
    }
    
    do {
        
        is (1, __, 'do while() loops execute at least once');
        
    } while (1 == 0);

    
    return (Perl::Koans::get_return_code()); 
}


sub about_until {
    # about_until()
    
    fail('about_until() has not been written');
    
    return (Perl::Koans::get_return_code()); 
}

# your code goes above this line
################


unless (caller(0)) {
    run(@ARGV) or print_illumination();
    exit();
}

sub run {
    # run() -- runs all functions in this module
    my $results = 0;
    
    $results += about_for();
    $results += about_while();
    $results += about_until();
    
    return ($results) ? bail($results) : $results;
}


1;