Andy Wardley > Badger > Badger::Utils



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Badger::Utils - various utility functions


    use Badger::Utils 'blessed params';

    sub example {
        my $self   = shift;
        my $params = params(@_);

        if (blessed $self) {
            print "self is blessed\n";


This module implements a number of utility functions. It also provides access to all of the utility functions in Scalar::Util, List::Util, List::MoreUtils, Hash::Util and Digest::MD5 as a convenience.

    use Badger::Utils 'blessed reftype first max any all lock_hash md5_hex';

The single line of code shown here will import blessed and reftype from Scalar::Util, first and max from List::Util, any and all from List::Util, lock_hash from Hash::Util, and md5_hex from Digest::MD5.

These modules are loaded on demand so there's no overhead incurred if you don't use them (other than a lookup table so we know where to find them).



Exports a UTILS constant which contains the name of the Badger::Utils class.


Badger::Utils can automatically load and export functions defined in the Scalar::Util, List::Util, List::MoreUtils, Hash::Util and Digest::MD5 Perl modules.

    use Badger::Utils 'blessed max md5_hex'

    # a rather contrived example
    if (blessed $some_ref) {
        print md5_hex(max @some_list);

Badger::Utils can also automatically load and export functions and constants defined in various other Badger modules. For example, you can use Badger::Utils to load the Now() function from Badger::Timestamp.

    use Badger::Utils 'Now';
    print Now->year;            # prints the current year



An alias for Badger::Duration.


A function to create a Badger::Duration object.

    use Badger::Utils 'Duration';

    my $duration = Duration('2 hours 20 minutes');
    print $duration->seconds;



An alias for Badger::Filesystem.


An alias for Badger::Filesystem::Virtual.


A function for creating a Badger::Filesystem::File object.

    my $f = File('filename');
    print $filename->modified;


A function for creating a Badger::Filesystem::Directory object.


Returns a Badger::Filesystem::Directory object for the directory in which the current script is located. See Bin() in Badger::Filesystem.


Returns a Badger::Filesystem::Directory object for the current working directory. See Cwd() in Badger::Filesystem.



An alias for Badger::Filter.


Function for returning a Badger::Filter object for filtering data.

    my $filter = Filter(
        include => [ qr/beer/ ],
        exclude => [ 'root beer' ],
    my @matches = $filter->accept(
        'beer', 'lite beer', 'root beer', 'soda'



An alias for Badger::Logic.


Function for returning a Badger::Logic object for representing simple logical assertions.

    my $logic  = Logic('trusted and not banned');
    my $person = {
        trusted => 1,
        banned  => 0,

    if ($logic->evaluate($person)) {



An alias for Badger::Timestamp.


A shorter alias for Badger::Timestamp.


Function for returning a Badger::Timestamp object representing the current date and time.

    print Now->date;


Function for creating a Badger::Timestamp object.

    my $stamp = Timestamp('2013-03-19 16:20:00');
    print $stamp->time;
    print $stamp->year;



Function for creating a Badger::URL object for representing and manipulating a URL.

    my $url = URL('');
    print $url->path;
    print $url->query;
    print $url->server;

Text Utility Functions


This function is used internally by the permute_fragments() function. It returns a reference to a list containing the alternates split from $text.

    alternates('foo|bar');          # returns ['foo','bar']
    alternates('foo');              # returns ['','bar']

If the $text doesn't contain the | character then it is assumed to be an optional item. A list reference is returned containing the empty string as the first element and the original $text string as the second.

camel_case($string) / CamelCase($string)

Converts a lower case string where words are separated by underscores (e.g. like_this_example) into CamelCase where each word is capitalised and words are joined together (e.g. LikeThisExample).

According to Perl convention (and personal preference), we use the lower case form wherever possible. However, Perl's convention also dictates that module names should be in CamelCase. This function performs that conversion.


The function returns a lower case representation of the text passed as an argument with all non-word character sequences replaced with dots.

    print dotid('Foo::Bar');            #

inflect($n, $noun, $format, $none_word)

This uses the plurality() function to construct an appropriate string listing the number $n of $noun items.

    inflect(0, 'package');      # no packages
    inflect(1, 'package');      # 1 package
    inflect(2, 'package');      # 2 packages


    inflect($n, 'wo(men|man|men');

The third optional argument can be used to specify a format string for xprintf to generate the string. The default value is %s %s, expecting the number (or word 'no') as the first parameter, followed by the relevant noun as the second.

    inflect($n, 'item', 'There are <b>%s</b> %s in your basket');

The fourth optional argument can be used to provide a word other than 'no' to be used when $n is zero.

        $n, 'item',
        'You have %s %s in your basket',
        'none, none more'

Please note that this function is intentionally limited. It's sufficient to generate simple headings, summary lines, etc., but isn't intended to be comprehensive or work in languages other than English.


This is an alias to the looks_like_number() function defined in Scalar::Util.


This function permutes any optional or alternate fragments embedded in parentheses. For example, Badger(X) is permuted as (Badger, BadgerX) and Badger(X|Y) is permuted as (BadgerX, BadgerY).

    permute_fragments('Badger(X)');     # Badger, BadgerX
    permute_fragments('Badger(X|Y)');   # BadgerX, BadgerY

Multiple fragments may be embedded. They are expanded in order from left to right, with the rightmost fragments changing most often.

    permute_fragments('A(1|2):B(3|4)')  # A1:B3, A1:B4, A2:B3, A2:B4


The function makes a very naive attempt at pluralising the singular noun word passed as an argument.

If the $noun word ends in ss, sh, ch or x then es will be added to the end of it.

    print plural('class');      # classes
    print plural('hash');       # hashes
    print plural('patch');      # patches
    print plural('box');        # boxes

If it ends in y then it will be replaced with ies.

    print plural('party');      # parties

In all other cases, s will be added to the end of the word.

    print plural('device');     # devices

It will fail miserably on many common words.

    print plural('woman');      # womans     FAIL!
    print plural('child');      # childs     FAIL!
    print plural('foot');       # foots      FAIL!

This function should only be used in cases where the singular noun is known in advance and has a regular form that can be pluralised correctly by the algorithm described above. For example, the Badger::Factory module allows you to specify $ITEM and $ITEMS package variable to provide the singular and plural names of the items that the factory manages.

    our $ITEM  = 'person';
    our $ITEMS = 'people';

If the singular noun is sufficiently regular then the $ITEMS can be omitted and the plural function will be used.

    our $ITEM  = 'codec';       # $ITEMS defaults to 'codecs'

In this case we know that codec will pluralise correctly to codecs and can safely leave $ITEMS undefined.

For more robust pluralisation of English words, you should use the Lingua::EN::Inflect module by Damian Conway. For further information on the difficulties of correctly pluralising English, and details of the implementation of Lingua::EN::Inflect, see Damian's paper "An Algorithmic Approach to English Pluralization" at

plurality($n, $noun)

This function can be used to construct the correct singular or plural form for a given number, $n, of a noun, $noun in the English language. For nouns that pluralise regularly (i.e. via the quick-and-dirty plural() function), the following is sufficient:

    plurality(0, 'package');      # packages
    plurality(1, 'package');      # package
    plurality(2, 'package');      # packages

For nouns that don't pluralise regularly, or where more complicated phrases should be constructed, the alternates for 0, 1 and 2 or more items can be specified in the format expected by permute_fragments().

    plurality($n, 'women|woman|women');     # 0 women, 1 woman, 2 women
    plurality($n, 'wo(men|man|men');        # optimised form


Generates a random name of maximum length $length using any additional seeding data passed as @args. If $length is undefined then the default value in $RANDOM_NAME_LENGTH (32) is used.

    my $name = random_name();
    my $name = random_name(64);


Returns true if $item is a non-reference scalar or an object that has an overloaded stringification operator.

    use Badger::Filesystem 'File';
    use Badger::Utils 'textlike';

    # Badger::Filesystem::File objects have overloaded string operator
    my $file = File('example.txt');
    print $file;                                # example.txt
    print textlike $file ? 'ok' : 'not ok';     # ok

wrap($text, $width, $indent)

Simple subroutine to wrap $text to a fixed $width, applying an optional indent of $indent spaces. It uses a trivial algorithm which splits the text into words, then rejoins them as lines. It has an additional hack to recognise the literal sequence '\n' as a magical word indicating a forced newline break. It must be specified as a separate whitespace delimited word.

    print wrap('Foo \n Bar');

If anyone knows how to make Text::Wrap handle this, or knows of a better solution then please let me know.


A wrapper around sprintf() which provides some syntactic sugar for embedding positional parameters.

    xprintf('The <2> sat on the <1>', 'mat', 'cat');
    xprintf('The <1> costs <2:%.2f>', 'widget', 11.99);

Hash Utility Functions

extend($hash, $another_hash, $yet_another_hash, ...)

This function merges the contents of several hash arrays into one. The first hash array will end up containing the keys and values of all the others.

    my $one = { a => 10 };
    my $two = { b => 20 };
    extend($one, $two);     # $one now contains a and b

If you want to create a new hash, simply pass an empty hash in as the first argument.

    my $mixed = extend(
        { },

You can also extend a hash array with named parameters.

        c => 30,
        d => 40,

You can mix and match the two calling conventions as long as any hash references come first.

        { },
        c => 30,
        d => 40,

merge($hash, $another_hash, $yet_another_hash, ...)

This function is a version of extend() that merges nested hash arrays to any depth.

    my $one = {
        a => 10,
        b => {
            c => 20,
            d => {
                e => 30,
    my $two = {
        b => {
            d => {
                f => 40
            g => 50,
        h => 60

    merge($one, $two);

After merging $one will contain:

        a => 10,
        b => {
            c => 20,
            d => {
                e => 30,
                f => 40
            g => 50,
        h => 60


Iterates over each key/value pair in the hash array referenced by the first argument, $hash, calling the function passed as the second argument, $function.

The function is called with 3 arguments: a reference to the hash array, the key of the current item and the value.

        { a => 10, b => 20 },
        sub {
            my ($hash, $key, $value) = @_;
            print "hash item $key is $value\n";

List Utility Functions


Iterates over each item in the array referenced by the first argument, $list, calling the function passed as the second argument, $function.

The function is called with 3 arguments: a reference to the list, the index of the current index (from 0 to size-1) and the item in the list at that index.

        sub {
            my ($list, $index, $item) = @_;
            print "list item #$index is $item\n";


This splits a string of words separated by whitespace (and/or commas) into a list reference. The following are all valid and equivalent:

    my $list = split_to_list("foo bar baz");    # => ['foo', 'bar', 'baz']
    my $list = split_to_list("foo,bar,baz");
    my $list = split_to_list("foo, bar, baz");

If the argument is already a list then it is returned unmodified.

Object Utility Functions


Returns true if the $object is a blessed reference which isa $class.

    use Badger::Filesystem 'FS';
    use Badger::Utils 'is_object';

    if (is_object( FS => $object )) {       # FS == Badger::Filesystem
        print $object, ' isa ', FS, "\n";

Parameter Handling Functions


Method to coerce a list of named parameters to a hash array reference. If the first argument is a reference to a hash array then it is returned. Otherwise the arguments are folded into a hash reference.

    use Badger::Utils 'params';

    params({ a => 10 });            # { a => 10 }
    params( a => 10 );              # { a => 10 }

Pro Tip: If you're getting warnings about an "Odd number of elements in anonymous hash" then try enabling debugging in Badger::Utils. To do this, add the following to the start of your program before you've loaded Badger::Utils:

    use Badger::Debug
        modules => 'Badger::Utils'

When debugging is enabled in Badger::Utils you'll get a full stack backtrace showing you where the subroutine was called from. e.g.

    Badger::Utils::self_params() called with an odd number of arguments: <undef>
    #1: Called from Foo::bar in /path/to/Foo/ at line 210
    #2: Called from Wam::bam in /path/to/Wam/ at line 420
    #3: Called from main in /path/to/your/ at line 217


Similar to params() but also expects a $self reference at the start of the argument list.

    use Badger::Utils 'self_params';

    sub example {
        my ($self, $params) = self_params(@_);
        # do something...

If you enable debugging in Badger::Utils then you'll get a stack backtrace in the event of an odd number of parameters being passed to this function. See params() for further details.


This is an internal function used by params() and self_params() to report any attempt to pass an odd number of arguments to either of them. It can be enabled by setting $Badger::Utils::DEBUG to a true value.

    use Badger::Utils 'params';
    $Badger::Utils::DEBUG = 1;

    my $hash = params( foo => 10, 20 );    # oops!

The above code will raise a warning showing the arguments passed and a stack backtrace, allowing you to easily track down and fix the offending code. Apart from obvious typos like the above, this is most likely to happen if you call a function or methods that returns an empty list. e.g.

        foo => 10,
        bar => get_the_bar_value(),

If get_the_bar_value() returns an empty list then you'll end up with an odd number of elements being passed to params(). You can correct this by providing undef as an alternative value. e.g.

        foo => 10,
        bar => get_the_bar_value() || undef,

URI Utility Functions

The following functions are provided for very simple manipulation of URI paths. You should consider using the URI module for anything non-trivial.

join_uri(frag1, frag2, etc)

Joins the elements of a URI passed as arguments into a single URI.

    use Contentity::Utils 'join_uri';
    print join_uri('/foo', 'bar');     # /foo/bar

resolve_uri(base, frag1, frag2, etc)

The first argument is a base URI. The remaining argument(s) are joined (via join_uri()) to construct a relative URI. If the relative URI begins with / then it is considered absolute and is returned unchanged. Otherwise it is appended to the base URI.

    use Contentity::Utils 'resolve_uri';
    print resolve_uri('/foo', 'bar/baz');     # /foo/bar/baz
    print resolve_uri('/foo', '/bar/baz');    # /bar/baz

Miscellanesou Utility Functions


Returns the module name passed as an argument as a relative filesystem path suitable for feeding into require()

    print module_file('My::Module');     # My/


Andy Wardley


Copyright (C) 1996-2013 Andy Wardley. All Rights Reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

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