Service returning a provider. More...

#include <ServiceProviderWrappers.h>

Public Types
using	provider_type = PROVIDER
	type of the service provider More...

using	Parameters = ::art::ServiceTable< typename provider_type::Config >
	Type of configuration parameter (for art description) More...

Public Member Functions
	SimpleServiceProviderWrapper (Parameters const &config,::art::ActivityRegistry &)
	Constructor (using a configuration table) More...

provider_type const *	provider () const
	Returns a constant pointer to the service provider. More...

Private Attributes
std::unique_ptr< provider_type >	prov
	service provider More...

Detailed Description

template<class PROVIDER>
class gar::SimpleServiceProviderWrapper< PROVIDER >

Service returning a provider.

Template Parameters

PROVIDER type of service provider to be returned

This class provides the simplest possible art service to wrap a GArSoft service provider. The service is not reacting to any framework events.

The configuration is passed directly to the provider.

The simplest way to create an art service with this template is:

#include "CoreUtils/ServiceProviderWrappers.h"
#include "path/to/MyProvider.h"

#include "art/Framework/Services/Registry/ServiceDeclarationMacros.h"
#include "art/Framework/Services/Registry/ServiceDefinitionMacros.h"

namespace myprov {

  using MyService = gar::SimpleServiceProviderWrapper<MyProvider>;

}

DECLARE_ART_SERVICE(myprov::MyService, LEGACY)

An implementation file is necessary too, that will look like:

#include "path/to/MyService.h"

DEFINE_ART_SERVICE(myprov::MyService)

If callback registration is needed, a class can derive from this template and still gain a bit of boilerplate facility. That is:

a provider_type definition (required by gar::providerFrom())
a provider() method to access the provider (required by gar::providerFrom())
a Parameters definition (used by art to print accepted configuration)
a constructor supporting FHiCL configuration validation
transparent life management of the provider instance

Requirements on the service provider:

a data type Config being the configuration object. This is the object wrapped by fhicl::Table when performing FHiCL validation.
a constructor with as argument a constant reference to a Config object. The provider should be configured by that constructor.

Definition at line 92 of file ServiceProviderWrappers.h.