aliased(3pm)

1aliased(3)            User Contributed Perl Documentation           aliased(3)
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NAME

6       aliased - Use shorter versions of class names.
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SYNOPSIS

9         # Class name interface
10         use aliased 'My::Company::Namespace::Customer';
11         my $cust = Customer->new;
12
13         use aliased 'My::Company::Namespace::Preferred::Customer' => 'Preferred';
14         my $pref = Preferred->new;
15
16         # Variable interface
17         use aliased;
18         my $Customer  = alias "My::Other::Namespace::Customer";
19         my $cust      = $Customer->new;
20
21         my $Preferred = alias "My::Other::Namespace::Preferred::Customer";
22         my $pref      = $Preferred->new;
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DESCRIPTION

25       "aliased" is simple in concept but is a rather handy module.  It loads
26       the class you specify and exports into your namespace a subroutine that
27       returns the class name.  You can explicitly alias the class to another
28       name or, if you prefer, you can do so implicitly.  In the latter case,
29       the name of the subroutine is the last part of the class name.  Thus,
30       it does something similar to the following:
31
32         #use aliased 'Some::Annoyingly::Long::Module::Name::Customer';
33
34         use Some::Annoyingly::Long::Module::Name::Customer;
35         sub Customer {
36           return 'Some::Annoyingly::Long::Module::Name::Customer';
37         }
38         my $cust = Customer->new;
39
40       This module is useful if you prefer a shorter name for a class.  It's
41       also handy if a class has been renamed.
42
43       (Some may object to the term "aliasing" because we're not aliasing one
44       namespace to another, but it's a handy term.  Just keep in mind that
45       this is done with a subroutine and not with typeglobs and weird names‐
46       pace munging.)
47
48       Note that this is only for "use"ing OO modules.  You cannot use this to
49       load procedural modules.  See the Why OO Only? section.  Also, don't
50       let the version number fool you.  This code is ridiculously simple and
51       is just fine for most use.
52
53       Implicit Aliasing
54
55       The most common use of this module is:
56
57         use aliased 'Some::Module::name';
58
59       "aliased" will  allow you to reference the class by the last part of
60       the class name.  Thus, "Really::Long::Name" becomes "Name".  It does
61       this by exporting a subroutine into your namespace with the same name
62       as the aliased name.  This subroutine returns the original class name.
63
64       For example:
65
66         use aliased "Acme::Company::Customer";
67         my $cust = Customer->find($id);
68
69       Note that any class method can be called on the shorter version of the
70       class name, not just the constructor.
71
72       Explicit Aliasing
73
74       Sometimes two class names can cause a conflict (they both end with
75       "Customer" for example), or you already have a subroutine with the same
76       name as the aliased name.  In that case, you can make an explicit alias
77       by stating the name you wish to alias to:
78
79         use aliased 'Original::Module::Name' => 'NewName';
80
81       Here's how we use "aliased" to avoid conflicts:
82
83         use aliased "Really::Long::Name";
84         use aliased "Another::Really::Long::Name" => "Aname";
85         my $name  = Name->new;
86         my $aname = Aname->new;
87
88       You can even alias to a different package:
89
90         use aliased "Another::Really::Long::Name" => "Another::Name";
91         my $aname = Another::Name->new;
92
93       Messing around with different namespaces is a really bad idea and you
94       probably don't want to do this.  However, it might prove handy if the
95       module you are using has been renamed.  If the interface has not
96       changed, this allows you to use the new module by only changing one
97       line of code.
98
99         use aliased "New::Module::Name" => "Old::Module::Name";
100         my $thing = Old::Module::Name->new;
101
102       Import Lists
103
104       Sometimes, even with an OO module, you need to specify extra arguments
105       when using the module.  When this happens, simply use "Explicit Alias‐
106       ing" followed by the import list:
107
108       Snippet 1:
109
110         use Some::Module::Name qw/foo bar/;
111         my $o = Some::Module::Name->some_class_method;
112
113       Snippet 2 (equivalent to snippet 1):
114
115         use aliased 'Some::Module::Name' => 'Name', qw/foo bar/;
116         my $o = Name->some_class_method;
117
118       Note:  remember, you cannot use import lists with "Implicit Aliasing".
119       As a result, you may simply prefer to only use "Explicit Aliasing" as a
120       matter of style.
121
122       alias()
123
124           my $alias = alias($class);
125           my $alias = alias($class, @imports);
126
127       alias() is an alternative to "use aliased ..." which uses less magic
128       and avoids some of the ambiguities.
129
130       Like "use aliased" it "use"s the $class (pass in @imports, if given)
131       but instead of providing an "Alias" constant it simply returns a scalar
132       set to the $class name.
133
134           my $thing = alias("Some::Thing::With::A::Long::Name");
135
136           # Just like Some::Thing::With::A::Long::Name->method
137           $thing->method;
138
139       The use of a scalar instead of a constant avoids any possible ambiguity
140       when aliasing two similar names:
141
142           # No ambiguity despite the fact that they both end with "Name"
143           my $thing = alias("Some::Thing::With::A::Long::Name");
144           my $other = alias("Some::Other::Thing::With::A::Long::Name");
145
146       and there is no magic constant exported into your namespace.
147
148       The only caveat is loading of the $class happens at run time.  If
149       $class exports anything you might want to ensure it is loaded at com‐
150       pile time with:
151
152           my $thing;
153           BEGIN { $thing = alias("Some::Thing"); }
154
155       However, since OO classes rarely export this should not be necessary.
156
157       Why OO Only?
158
159       Some people have asked why this code only support object-oriented mod‐
160       ules (OO).  If I were to support normal subroutines, I would have to
161       allow the following syntax:
162
163         use aliased 'Some::Really::Long::Module::Name';
164         my $data = Name::data();
165
166       That causes a serious problem.  The only (reasonable) way it can be
167       done is to handle the aliasing via typeglobs.  Thus, instead of a sub‐
168       routine that provides the class name, we alias one package to another
169       (as the namespace module does.)  However, we really don't want to sim‐
170       ply alias one package to another and wipe out namespaces willy-nilly.
171       By merely exporting a single subroutine to a namespace, we minimize the
172       issue.
173
174       Fortunately, this doesn't seem to be that much of a problem.  Non-OO
175       modules generally support exporting of the functions you need and this
176       eliminates the need for a module such as this.
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EXPORT

179       This modules exports a subroutine with the same name as the "aliased"
180       name.
181

BUGS

183       There are no known bugs in this module, but feel free to email me
184       reports.
185

THANKS

190       Many thanks to Rentrak, Inc. (http://www.rentrak.com/) for graciously
191       allowing me to replicate the functionality of some of their internal
192       code.
193

AUTHOR

195       Curtis Poe, "ovid [at] cpan [dot] org"
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COPYRIGHT AND LICENSE

198       Copyright (C) 2005 by Curtis "Ovid" Poe
199
200       This library is free software; you can redistribute it and/or modify it
201       under the same terms as Perl itself, either Perl version 5.8.5 or, at
202       your option, any later version of Perl 5 you may have available.
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206perl v5.8.8                       2007-03-30                        aliased(3)