1HTML::Mason::Component(U3s)er Contributed Perl DocumentatHiToMnL::Mason::Component(3)
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NAME

6       HTML::Mason::Component - Mason Component Class
7

SYNOPSIS

9           my $comp1 = $m->current_comp;
10           my $comp2 = $m->callers(1);
11           my $comp3 = $m->fetch_comp('foo/bar');
12
13           foreach ($comp1,$comp2,$comp3) {
14              print "My name is ".$_->title.".\n";
15           }
16

DESCRIPTION

18       Mason uses the Component class to store components loaded into memory.
19       Components come from three distinct sources:
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21       1.  File-based: loaded from a source or object file.
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23       2.  Subcomponents: embedded components defined with the "<%def>" or
24           "<%method>" tags.
25
26       3.  Anonymous: created on-the-fly with the "make_component" Interp
27           method.
28
29       Some of the methods below return different values (or nothing at all)
30       depending on the component type.
31
32       The component API is primarily useful for introspection, e.g. "what
33       component called me" or "does the next component take a certain
34       argument".  You can build complex Mason sites without ever dealing
35       directly with a component object.
36
37   CREATING AND ACCESSING COMPONENTS
38       Common ways to get handles on existing component objects include the
39       Request->current_comp, Request->callers, and Request->fetch_comp
40       methods.
41
42       There is no published "new" method, because creating a component
43       requires an Interpreter. Use the make_component method to create a new
44       component dynamically.
45
46       Similarly, there is no "execute" or "call" method, because calling a
47       component requires a request. All of the interfaces for calling a
48       component ("<& &>", "$m->comp", "$interp->exec") which normally take a
49       component path will also take a component object.
50

METHODS

52       attr (name)
53           Looks for the specified attribute in this component and its
54           parents, returning the first value found. Dies with an error if not
55           found. Attributes are declared in the "<%attr>" section.
56
57       attr_if_exists (name)
58           This method works exactly like the one above but returns undef if
59           the attribute does not exist.
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61       attr_exists (name)
62           Returns true if the specified attribute exists in this component or
63           one of its parents, undef otherwise.
64
65       attributes
66           Returns a hashref containing the attributes defined in this
67           component, with the attribute names as keys.  This does not return
68           attributes inherited from parent components.
69
70       call_method (name, args...)
71           Looks for the specified user-defined method in this component and
72           its parents, calling the first one found. Dies with an error if not
73           found.  Methods are declared in the "<%method>" section.
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75       create_time
76           A synonym for load_time (deprecated).
77
78       declared_args
79           Returns a reference to a hash of hashes representing the arguments
80           declared in the "<%args>" section. The keys of the main hash are
81           the variable names including prefix (e.g. $foo, @list). Each
82           secondary hash contains:
83
84           •   'default': the string specified for default value (e.g. 'fido')
85               or undef if none specified.  Note that in general this is not
86               the default value itself but rather a Perl expression that gets
87               evaluated every time the component runs.
88
89           For example:
90
91             # does $comp have an argument called $fido?
92             if (exists($comp->declared_args->{'$fido'})) { ... }
93
94             # does $fido have a default value?
95             if (defined($comp->declared_args->{'$fido'}->{default})) { ... }
96
97       dir_path
98           Returns the component's notion of a current directory, relative to
99           the component root; this is used to resolve relative component
100           paths. For file-based components this is the full component path
101           minus the filename.  For subcomponents this is the same as the
102           component that defines it.  Undefined for anonymous components.
103
104       flag (name)
105           Returns the value for the specified system flag.  Flags are
106           declared in the "<%flags>" section and affect the behavior of the
107           component.  Unlike attributes, flags values do not get inherited
108           from parent components.
109
110       is_subcomp
111           Returns true if this is a subcomponent of another component.  For
112           historical reasons, this returns true for both methods and
113           subcomponents.
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115       is_method
116           Returns true if this is a method.
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118       is_file_based
119           Returns true if this component was loaded from a source or object
120           file.
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122       load_time
123           Returns the time (in Perl time() format) when this component object
124           was created.
125
126       method_exists (name)
127           Returns true if the specified user-defined method exists in this
128           component or one of its parents, undef otherwise.
129
130       methods
131           This method works exactly like the subcomps method, but it returns
132           methods, not subcomponents.  This does not return methods inherited
133           from parent components.
134
135           Methods are declared in "<%method>" sections.
136
137       name
138           Returns a short name of the component.  For file-based components
139           this is the filename without the path. For subcomponents this is
140           the name specified in "<%def>". Undefined for anonymous components.
141
142       object_file
143           Returns the object filename for this component.
144
145       parent
146           Returns the parent of this component for inheritance purposes, by
147           default the nearest "autohandler" in or above the component's
148           directory.  Can be changed via the "inherit" flag.
149
150       path
151           Returns the entire path of this component, relative to the
152           component root.
153
154       scall_method (name, args...)
155           Like item_call_method, but returns the method output as a string
156           instead of printing it. (Think sprintf versus printf.) The method's
157           return value, if any, is discarded.
158
159       subcomps
160           With no arguments, returns a hashref containing the subcomponents
161           defined in this component, with names as keys and component objects
162           as values.  With one argument, returns the subcomponent of that
163           name or undef if no such subcomponent exists. e.g.
164
165               if (my $subcomp = $comp->subcomps('.link')) {
166                   ...
167               }
168
169           Subcomponents are declared in "<%def>" sections.
170
171       title
172           Returns a printable string denoting this component.  It is intended
173           to uniquely identify a component within a given interpreter
174           although this is not 100% guaranteed. Mason uses this string in
175           error messages, among other places.
176
177           For file-based components this is the component path.  For
178           subcomponents this is "parent_component_path:subcomponent_name".
179           For anonymous components this is a unique label like "[anon 17]".
180

FILE-BASED METHODS

182       The following methods apply only to file-based components (those loaded
183       from source or object files). They return undef for other component
184       types.
185
186       source_file
187           Returns the source filename for this component.
188
189       source_dir
190           Returns the directory of the source filename for this component.
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194perl v5.32.1                      2021-01-27         HTML::Mason::Component(3)
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