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HTML::Mason::Component - Mason Component Class
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HTML::Mason::Component - Mason Component Class
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";
}
Mason uses the Component class to store components loaded into
memory. Components come from three distinct sources:
-
File-based: loaded from a source or object file.
-
Subcomponents: embedded components defined with the
<%def> tag.
-
Anonymous: created on-the-fly with the
make_component Parser 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.
Common ways to get handles on existing component objects include the
current_comp in the Request manpage, callers in the Request manpage, and fetch_comp in the Request manpage Request methods.
There is no published new method, because creating a component
requires a parser. Use the make_component in the Parser manpage Parser 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.
- 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_exists (name)
-
Returns true if the specified attribute exists in this component or
one of its parents, undef otherwise.
- cache_file
-
Returns the data cache filename for this component.
- create_time
-
Returns the time (in Perl
time() format) when this component object
was created.
- 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, @lst). 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 an 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->{'$fido'}->{default})) { ... }
- dir_path
-
Returns the component's notion of a current directory, relative to the
component root; this is used to resolve relative component paths. For
file-based components this is the full component path minus the final
piece. For subcomponents this is the same as its parent component.
Undefined for anonymous components.
- first_time
-
Returns true if this is the first time the component has executed,
false otherwise. Useful for initializing persistent component
lexicals:
if ($m->current_comp->first_time) {
$dbh = DBI->connect(...);
Note that in a web-based environment, this ``first time'' will
come once for each child and every time the component is reloaded.
- flag (name)
-
Returns the value for the specified system flag. Flags are declared
in the
<%flags> section and affect the behavior of the component.
- is_subcomp
-
Returns true if this is a subcomponent of another component.
- is_file_based
-
Returns true if this component was loaded from a source or object
file.
- 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.
- method_exists (name)
-
Returns true if the specified user-defined method exists in this
component or one of its parents, undef otherwise.
- 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.
- owner
-
Defined only for subcomponents; returns the component that this
subcomponent was defined in.
- 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 absolute path of this component.
- run_count
-
Returns the number of times this component has been invoked. In a
web-based environment, this value is separate for each child and
resets every time the component is reloaded.
- scall_method (name, args...)
-
Like call_method (name, args...) in the Component manpage, but returns the method
output as a string instead of printing it. (Think sprintf versus
printf.) The method's return value 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 the <%def> section.
- 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,
the previewer component trace, and
$m-comp_stack>.
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]''.
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.
Jonathan Swartz, swartz@pobox.com
the HTML::Mason::Request manpage
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HTML::Mason::Component - Mason Component Class
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