Input::Factory< Type, Arguments > Class Template Reference

This class implements more general factory mechanism to construct classes. More...

#include <factory.hh>

Collaboration diagram for Input::Factory< Type, Arguments >:

Public Member Functions
shared_ptr< Type > const	create (string name, Arguments... arguments) const
	create an instance of a registered class More...

Static Public Member Functions
static Factory *	instance ()
	Get the single instance of the factory. More...
template<class Child >
static int	register_class (string class_name)
	Register lambda function that calls default constructor of Type. More...

Private Member Functions
	Factory ()
	Forbid default constructor. More...

Private Attributes
map< string, boost::any >	factory_registry_
	the registry of factory functions More...

Detailed Description

template<class Type, class... Arguments>
class Input::Factory< Type, Arguments >

This class implements more general factory mechanism to construct classes.

One factory allows constructing derived classes of one base class. This class is determined by template parameter Type and all descendants must implement constructor with same parameters (given by template parameter Arguments). This constructor is called by factory.

All descendants must contain:

1. constructor with parameters given by Arguments
2. declaration of parent class as typedef with name FactoryBaseType
3. private static integer variable what is only for registration class to factory, this variable only allow to register class to factory and its implementation must call: (a) Factory::register_class that adds constructor of class to factory (b) generating function of Input::Type::Record (usually get_input_type() method)

Simple example of usage:

class SomeDescendant : public SomeBase
{
public:
   /// typedef of parent class
   typedef SomeBase FactoryBaseType;
 
   /// Return initialization Record
   static const Input::Type::Record & get_input_type();
 
/// constructor
   SomeDescendant() {}
 
private:
    /// registers class to factory
    static const int reg;
}
 
/// implementation of registration variable
const int SomeDescendant::reg =
 Input::register_class< SomeDescendant >("SomeDescendant") +
 SomeDescendant::get_input_type().size();

Factory allow to accept constructor with one or more parameters. In this case Factory is also templated by these parameters. For example Factory< SomeBase, int, double > accepts constructors with two parameters (int, double).

If registered class is templated the following design have to be used:

/// Example of class templated by integer parameter
template <int dimension>
class SomeDescendant : public SomeBase<dimension>
{
public:
 
/// constructor
   SomeDescendant(double time) {}
    ...
}
 
/// implementation of registration variable
const int SomeDescendant::reg =
 Input::register_class< SomeDescendant<dimension>, double >("SomeDescendant") +
 SomeDescendant<dimension>::get_input_type().size();

Factory can be used in two ways:

• through Factory::create method Example for constructor with one parameter:

  SomeBase * sb = Input::Factory< SomeBase, double >::instance()->create("SomeDescendant", 0.1);

• through AbstractRecord::factory method. This possibility can be used if base class has defined AbstractRecord and its descendants contain Record derived from this AbstractRecord. Example for same constructor:

  AbstractRecord a_rec = record.val<AbstractRecord>("problem");
  SomeBase * sb = a_rec.factory< SomeBase, double>(0.25);
  // If arguments types can be deduced (by compiler) from actual arguments one can even use:
  SomeBase * sb = a_rec.factory< SomeBase >(0.25);

For correct functionality must be used two macros defined in global_defs.h:

• FLOW123D_FORCE_LINK_IN_CHILD(x)
• FLOW123D_FORCE_LINK_IN_PARENT(x) First is used in C source file of descendant class out of class methods, e.g.: FLOW123D_FORCE_LINK_IN_CHILD(gmsh) Second is used in C source file of parent class in any of class method with same parameter as in first used, e.g.: FLOW123D_FORCE_LINK_IN_PARENT(gmsh)

Definition at line 132 of file factory.hh.

Constructor & Destructor Documentation

Factory()

template<class Type , class... Arguments>

Input::Factory< Type, Arguments >::Factory ( )

inlineprivate

Forbid default constructor.

Definition at line 150 of file factory.hh.

Member Function Documentation

create()

template<class Type , class... Arguments>

const shared_ptr< Type > Input::Factory< Type, Arguments >::create	(	string	name,
		Arguments...	arguments
	)		const

create an instance of a registered class

Definition at line 49 of file factory_impl.hh.

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instance()

template<class Type , class... Arguments>

Factory< Type, Arguments... > * Input::Factory< Type, Arguments >::instance

static

Get the single instance of the factory.

Definition at line 27 of file factory_impl.hh.

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register_class()

template<class Type , class... Arguments>

template<class Child >

int Input::Factory< Type, Arguments >::register_class ( string  class_name )

static

Register lambda function that calls default constructor of Type.

Definition at line 36 of file factory_impl.hh.

Member Data Documentation

factory_registry_

template<class Type , class... Arguments>

map<string, boost::any> Input::Factory< Type, Arguments >::factory_registry_

private

the registry of factory functions

Definition at line 153 of file factory.hh.

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The documentation for this class was generated from the following files:

• /home/runner/work/flow123d/flow123d/src/input/factory.hh
• /home/runner/work/flow123d/flow123d/src/input/factory_impl.hh