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Fortran Module

The general form is ~~~~~~~~~~~ {: lang=fortran } module <name>

contains

end module <name> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

There are three possible access properties: `public, private, protected`.

One can include the module's public data in outside code. There are three ways.

`use <moduleName>`: includes all public data and methods
`use <moduleName>, <renames>`: includes all public data and methods, but renames some public data or methods
`use <moduleName>, only : <subset>`: includes only some public data and methods

These examples highlight the above methods using the following module.

~~~~~~~~~~~ {: lang=fortran } !> \\file test_module.f module test_module

 implicit none
 private
 integer, public :: a=1
 integer, public, protected :: b=1
 integer, private :: c=1

end module test_module ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

~~~~~~~~~~~ {: lang=fortran } !> \\file main.f program main

 use test_module

 ! accessing public object works
 print *, a

 ! editing public object works
 a = 2

 ! accessing protected object works
 print *, b

 ! editing protected object does not work
 !b = 2 <- ERROR

 ! accessing private object does not work
 !print *, c <- ERROR

 ! editing protected object does not work
 !c = 2 <- ERROR

end program main ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

~~~~~~~~~~~ {: lang=fortran } !> \\file main1.f program main

 use test_module

 print *, a, b

end program main ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

~~~~~~~~~~~ {: lang=fortran } !> \\file main2.f program main

 use test_module, better_name => a

 ! new name use available
 print *, better_name

 ! old name is not available anymore
 !print *, a  <- ERROR

end program main

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

~~~~~~~~~~~ {: lang=fortran } !> show using only program main

 use test_module, only : a

 ! only a is loaded
 print *, a

 ! b is not loaded
 !print *, b  <- ERROR

end program main

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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