fortran90 - Store a "pointer to function" in fortran 90? -

in fortran, can pass function/subroutine argument function/subroutine b, can store later retrieval , use?

for example, allowed in c

int foo(float, char, char) { /*whatever*/};  int (*pointertofunction)(float, char, char); pointertofunction = foo; 

in fortran can pass subroutine argument

subroutine foo ! whatever end subroutine foo  subroutine bar(func)     call func end subroutine bar  program x      call bar(foo)  end program 

but how can store address of foo in similar way c ?

starting so-called "fortran 2003" (iso/iec 1539-2004) procedure pointers part of fortran language. it's of major new features of fortran language.

usage example fortran wiki.

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stefano, mentioned strategy design pattern. in fortran 2003 can use pure oop way implement (without procedure pointers). offhand example:

strategies.f90

module strategies    implicit none    private    public :: strategies_transportation_strategy, &             strategies_by_taxi_strategy, &             strategies_by_bus_strategy    type, abstract :: strategies_transportation_strategy   contains     procedure(transportation_strategy_go), deferred :: go   end type strategies_transportation_strategy    type, extends(strategies_transportation_strategy) :: strategies_by_taxi_strategy   contains     procedure :: go => strategies_by_taxi_strategy_go   end type strategies_by_taxi_strategy    type, extends(strategies_transportation_strategy) :: strategies_by_bus_strategy   contains     procedure :: go => strategies_by_bus_strategy_go   end type strategies_by_bus_strategy    abstract interface     subroutine transportation_strategy_go(this)       import strategies_transportation_strategy       class(strategies_transportation_strategy), intent(in) ::     end subroutine transportation_strategy_go   end interface    contains      subroutine strategies_by_taxi_strategy_go(this)       class(strategies_by_taxi_strategy), intent(in) ::        print *, "we using taxi."      end subroutine strategies_by_taxi_strategy_go      subroutine strategies_by_bus_strategy_go(this)       class(strategies_by_bus_strategy), intent(in) ::        print *, "we using public transport."      end subroutine strategies_by_bus_strategy_go  end module strategies 

vehicles.f90

module vehicles    use strategies    implicit none    private    public :: vehicles_vehicle, &             vehicles_taxi, &             vehicles_bus    type, abstract :: vehicles_vehicle     private     class(strategies_transportation_strategy), allocatable :: transportation_strategy   contains     procedure :: set_transportation_strategy => vehicle_set_transportation_strategy     procedure :: go => vehicle_go   end type vehicles_vehicle    type, extends(vehicles_vehicle) :: vehicles_taxi   contains     procedure :: init => taxi_init   end type vehicles_taxi    type, extends(vehicles_vehicle) :: vehicles_bus   contains     procedure :: init => bus_init   end type vehicles_bus    contains      subroutine vehicle_go(this)       class(vehicles_vehicle), intent(in) ::        call this%transportation_strategy%go()      end subroutine vehicle_go      subroutine vehicle_set_transportation_strategy(this, new_transportation_strategy)       class(vehicles_vehicle), intent(inout) ::       class(strategies_transportation_strategy), intent(in) :: new_transportation_strategy        if (allocated(this%transportation_strategy))         deallocate (this%transportation_strategy)       end if        allocate (this%transportation_strategy, source=new_transportation_strategy)      end subroutine vehicle_set_transportation_strategy      subroutine taxi_init(this)       class(vehicles_taxi), intent(out) ::        type(strategies_by_taxi_strategy) :: by_taxi_strategy        call this%set_transportation_strategy(by_taxi_strategy)      end subroutine taxi_init      subroutine bus_init(this)       class(vehicles_bus), intent(out) ::        type(strategies_by_bus_strategy) :: by_bus_strategy        call this%set_transportation_strategy(by_bus_strategy)      end subroutine bus_init  end module vehicles 

main.f90

program main    use vehicles    implicit none    type(vehicles_taxi) :: taxi   type(vehicles_bus) :: bus    call taxi%init()   call bus%init()    call taxi%go()   call bus%go()  end program main 

at least works using gfortran 4.6 (20100925).