NAME

Data::Miscellany - collection of miscellaneous subroutines

SYNOPSIS

use Data::Miscellany qw/set_push flex_grep/;

@foo = (1, 2, 3, 4);
set_push @foo, 3, 1, 5, 1, 6;
# @foo is now (1, 2, 3, 4, 5, 6)

flex_grep('foo', [ qw/foo bar baz/ ])                     # true
flex_grep('foo', [ qw/bar baz flurble/ ])                 # false
flex_grep('foo', 1..4, 'flurble', [ qw/foo bar baz/ ])    # true
flex_grep('foo', 1..4, [ [ 'foo' ] ], [ qw/bar baz/ ])    # false

DESCRIPTION

This is a collection of miscellaneous subroutines useful in wide but varying scenarios; a catch-all module for things that don't obviously belong anywhere else. Obviously what's useful differs from person to person, but this particular collection should be useful in object-oriented frameworks, such as Class::Framework and Data::Conveyor.

SUBROUTINES

set_push ARRAY, LIST

Like push(), but only pushes the item(s) onto the list indicated by the list or list ref (the first argument) if the list doesn't already contain it.

Example:

@foo = (1, 2, 3, 4);
set_push @foo, 3, 1, 5, 1, 6;
# @foo is now (1, 2, 3, 4, 5, 6)

flatten()

If the first argument is an array reference, it returns the dereferenced array. If the first argument is undefined (or there are no arguments), it returns the empty list. Otherwise the argument list is returned as is.

flex_grep(SCALAR, LIST)

Like grep(), but compares the first argument to each flattened (see flatten()) version of each element of the list.

Examples:

flex_grep('foo', [ qw/foo bar baz/ ])                     # true
flex_grep('foo', [ qw/bar baz flurble/ ])                 # false
flex_grep('foo', 1..4, 'flurble', [ qw/foo bar baz/ ])    # true
flex_grep('foo', 1..4, [ [ 'foo' ] ], [ qw/bar baz/ ])    # false

is_deeply()

Like Test::More's is_deeply() except that this version respects stringification overloads. If a package overloads stringification, it means that it specifies how it wants to be compared. Recent versions of Test::More break this behaviour, so here is a working version of is_deeply(). This subroutine only does the comparison; there are no test diagnostics or results recorded or printed anywhere.

eq_array()

Like Test::More's eq_array() except that this version respects stringification overloads. If a package overloads stringification, it means that it specifies how it wants to be compared. Recent versions of Test::More break this behaviour, so here is a working version of eq_array(). This subroutine only does the comparison; there are no test diagnostics or results recorded or printed anywhere.

eq_hash()

Like Test::More's eq_hash() except that this version respects stringification overloads. If a package overloads stringification, it means that it specifies how it wants to be compared. Recent versions of Test::More break this behaviour, so here is a working version of eq_hash(). This subroutine only does the comparison; there are no test diagnostics or results recorded or printed anywhere.

is_defined(SCALAR)

A kind of defined() that is aware of Class::Value, which has its own views of what is a defined value and what isn't. The issue arose since Class::Value objects are supposed to be used transparently, mixed with normal scalar values. However, it is not possible to overload "definedness", and defined() used on a value object always returns true since the object reference certainly exists. However, what we want to know is whether the value encapsulated by the value object is defined. Additionally, each value class can have its own ideas of when its encapsulated value is defined. Therefore, Class::Value has an is_defined() method.

This subroutine checks whether its argument is a value object and if so, calls the value object's is_defined() method. Otherwise, the normal defined() is used.

value_of(SCALAR)

Stringifies its argument, but returns undefined values (per is_defined()) as undef.

str_value_of(SCALAR)

Stringifies its argument, but returns undefined values (per is_defined()) as the empty string.

class_map(SCALAR, HASH)

Takes an object or class name as the first argument (if it's an object, the class name used will be the package name the object is blessed into). Takes a hash whose keys are class names as the second argument. The hash values are completely arbitrary.

Looks up the given class name in the hash and returns the corresponding value. If no such hash key is found, the class hierarchy for the given class name is traversed depth-first and checked against the hash keys in turn. The first value found is returned.

If no key is found, a special key, UNIVERSAL is used.

As an example of how this might be used, consider a hierarchy of exception classes. When evaluating each exception, we want to know how severe this exception is, so we define constants for RC_OK (meaning it's informational only), RC_ERROR (meaning some sort of action should be taken) and RC_INTERNAL_ERROR (meaning something has gone badly wrong and we might halt processing). In the following table assume that if you have names like Foo::Bar and Foo::Bar::Baz, then the latter subclasses the former.

%map = (
    'UNIVERSAL'                                => RC_INTERNAL_ERROR,
    'My::Exception::Business'                  => RC_ERROR,
    'My::Exception::Internal'                  => RC_INTERNAL_ERROR,
    'My::Exception::Business::ValueNormalized' => RC_OK,
);

Assuming that My::Exception::Business::IllegalValue exists and that it subclasses My::Exception::Business, here are some outcomes:

class_map('My::Exception::Business::IllegalValue', \%map)     # RC_ERROR
class_map('My::Exception::Business::ValueNormalzed', \%map)   # RC_OK

TAGS

If you talk about this module in blogs, on del.icio.us or anywhere else, please use the datamiscellany tag.

BUGS AND LIMITATIONS

No bugs have been reported.

Please report any bugs or feature requests to bug-data-miscellany@rt.cpan.org, or through the web interface at http://rt.cpan.org.

INSTALLATION

See perlmodinstall for information and options on installing Perl modules.

AVAILABILITY

The latest version of this module is available from the Comprehensive Perl Archive Network (CPAN). Visit <http://www.perl.com/CPAN/> to find a CPAN site near you. Or see <http://www.perl.com/CPAN/authors/id/M/MA/MARCEL/>.

AUTHOR

Marcel Grünauer, <marcel@cpan.org>

COPYRIGHT AND LICENSE

Copyright 2007 by Marcel Grünauer

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