HTML::Mason::ComponentUser Contributed Perl DocumentaHTML::Mason::Component(3)NAMEHTML::Mason::Component - Mason Component Class
VERSION
version 1.54
SYNOPSIS
my $comp1 = $m->current_comp;
my $comp2 = $m->callers(1);
my $comp3 = $m->fetch_comp('foo/bar');
foreach ($comp1,$comp2,$comp3) {
print "My name is ".$_->title.".\n";
}
DESCRIPTION
Mason uses the Component class to store components loaded into memory.
Components come from three distinct sources:
1. File-based: loaded from a source or object file.
2. Subcomponents: embedded components defined with the "<%def>" or
"<%method>" tags.
3. Anonymous: created on-the-fly with the "make_component" Interp
method.
Some of the methods below return different values (or nothing at all)
depending on the component type.
The component API is primarily useful for introspection, e.g. "what
component called me" or "does the next component take a certain
argument". You can build complex Mason sites without ever dealing
directly with a component object.
CREATING AND ACCESSING COMPONENTS
Common ways to get handles on existing component objects include the
Request->current_comp, Request->callers, and Request->fetch_comp
methods.
There is no published "new" method, because creating a component
requires an Interpreter. Use the make_component method to create a new
component dynamically.
Similarly, there is no "execute" or "call" method, because calling a
component requires a request. All of the interfaces for calling a
component ("<& &>", "$m->comp", "$interp->exec") which normally take a
component path will also take a component object.
METHODS
attr (name)
Looks for the specified attribute in this component and its
parents, returning the first value found. Dies with an error if not
found. Attributes are declared in the "<%attr>" section.
attr_if_exists (name)
This method works exactly like the one above but returns undef if
the attribute does not exist.
attr_exists (name)
Returns true if the specified attribute exists in this component or
one of its parents, undef otherwise.
attributes
Returns a hashref containing the attributes defined in this
component, with the attribute names as keys. This does not return
attributes inherited from parent components.
call_method (name, args...)
Looks for the specified user-defined method in this component and
its parents, calling the first one found. Dies with an error if not
found. Methods are declared in the "<%method>" section.
create_time
A synonym for load_time (deprecated).
declared_args
Returns a reference to a hash of hashes representing the arguments
declared in the "<%args>" section. The keys of the main hash are
the variable names including prefix (e.g. $foo, @list). Each
secondary hash contains:
· 'default': the string specified for default value (e.g. 'fido')
or undef if none specified. Note that in general this is not
the default value itself but rather a Perl expression that gets
evaluated every time the component runs.
For example:
# does $comp have an argument called $fido?
if (exists($comp->declared_args->{'$fido'})) { ... }
# does $fido have a default value?
if (defined($comp->declared_args->{'$fido'}->{default})) { ... }
dir_path
Returns the component's notion of a current directory, relative to
the component root; this is used to resolve relative component
paths. For file-based components this is the full component path
minus the filename. For subcomponents this is the same as the
component that defines it. Undefined for anonymous components.
flag (name)
Returns the value for the specified system flag. Flags are
declared in the "<%flags>" section and affect the behavior of the
component. Unlike attributes, flags values do not get inherited
from parent components.
is_subcomp
Returns true if this is a subcomponent of another component. For
historical reasons, this returns true for both methods and
subcomponents.
is_method
Returns true if this is a method.
is_file_based
Returns true if this component was loaded from a source or object
file.
load_time
Returns the time (in Perl time() format) when this component object
was created.
method_exists (name)
Returns true if the specified user-defined method exists in this
component or one of its parents, undef otherwise.
methods
This method works exactly like the subcomps method, but it returns
methods, not subcomponents. This does not return methods inherited
from parent components.
Methods are declared in "<%method>" sections.
name
Returns a short name of the component. For file-based components
this is the filename without the path. For subcomponents this is
the name specified in "<%def>". Undefined for anonymous components.
object_file
Returns the object filename for this component.
parent
Returns the parent of this component for inheritance purposes, by
default the nearest "autohandler" in or above the component's
directory. Can be changed via the "inherit" flag.
path
Returns the entire path of this component, relative to the
component root.
scall_method (name, args...)
Like item_call_method, but returns the method output as a string
instead of printing it. (Think sprintf versus printf.) The method's
return value, if any, is discarded.
subcomps
With no arguments, returns a hashref containing the subcomponents
defined in this component, with names as keys and component objects
as values. With one argument, returns the subcomponent of that
name or undef if no such subcomponent exists. e.g.
if (my $subcomp = $comp->subcomps('.link')) {
...
}
Subcomponents are declared in "<%def>" sections.
title
Returns a printable string denoting this component. It is intended
to uniquely identify a component within a given interpreter
although this is not 100% guaranteed. Mason uses this string in
error messages, among other places.
For file-based components this is the component path. For
subcomponents this is "parent_component_path:subcomponent_name".
For anonymous components this is a unique label like "[anon 17]".
FILE-BASED METHODS
The following methods apply only to file-based components (those loaded
from source or object files). They return undef for other component
types.
source_file
Returns the source filename for this component.
source_dir
Returns the directory of the source filename for this component.
SEE ALSO
Mason
AUTHORS
· Jonathan Swartz <swartz@pobox.com>
· Dave Rolsky <autarch@urth.org>
· Ken Williams <ken@mathforum.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2012 by Jonathan Swartz.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
perl v5.18.2 2014-01-19 HTML::Mason::Component(3)
