Used to specify the default template that should be used for a header. It can be specified as anything that the Template::TT3::Templates template() method will accept, e.g. a template name, text references, subroutine reference, etc.

template is the default option for the service. Thus the following:

my $header = Template::TT3::Services->service(
    header => 'site/header.tt3',
);

is syntactic sugar for:

my $header = Template::TT3::Services->service(
    header => {
        template => 'site/header.tt3',
    },
);

This can be used to change the name of the service component. The default name is header. If a header is specified in the environment passed to the pipeline service function then it will be used in preference to the default template .

$pipeline->(
    context => $context,
    input   => 'example.tt3',
    header  => 'my/header.tt3',     # over-ride default header template
);

If you want to have several different header services in the same pipeline then you should give them unique names. For example, you might set one to site_header and the other to section_header. This allows you to change the name of either independently.

$pipeline->(
    context        => $context,
    input          => 'example.tt3',
    site_header    => 'site/header.tt3',
    section_header => 'section/products/header.tt3',
);

This is the main service method. It is called automatically when the service is bound in a pipeline that is executed. A copy of the environment is passed as the first argument (a reference to a hash array). A reference to a subroutine representing the rest of the pipeline is passed as the second argument.

The method looks in the environment for an item named header, or whatever alternate name the service has been given (e.g. site_header, section_header, etc). If the item isn't specified then it instead uses the default header template defined when the service is created. If that is undefined or set to a false value (e.g. 0 or the empty string '') then no header is added.

Otherwise it processes the header template and then executes the $pipeline function to render the rest of the service pipeline. It returns the output generated from the header concatenated with that returned by the $pipeline function. If no header is specified then it returns only the output from the $pipeline function.