HTML::Mason::Component - phpMan

NAME
    HTML::Mason::Component - Mason Component Class

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.