[讨论] 如何判断两个无限多态变量相等

program main
	implicit none
	write(*,*)EqualClass(1,2)
	write(*,*)EqualClass(1,1)
	write(*,*)EqualClass(1.0,1.001)
	write(*,*)EqualClass(1.0,1.0)
	write(*,*)EqualClass('abc','abcd')
	write(*,*)EqualClass('abc','abc')
	write(*,*)EqualClass(.true.,.false.)
	write(*,*)EqualClass(.true.,.true.)
contains
pure logical function EqualClass(self, other)
	class(*), intent(in) :: self
	class(*), intent(in) :: other
	EqualClass=.false. !初值为假

	select type(self)
		type is(Integer)
			select type(other)
				type is(Integer)
					EqualClass=(self==other)
			end select
		type is(Real)
			select type(other)
				type is(Real)
					EqualClass=(abs(self-other)<1.0e-5)
			end select
		type is(Character(*))
			select type(other)
				type is(Character(*))
          EqualClass=(self==other)
			end select
		type is(Logical)
			select type(other)
				type is(Logical)
					EqualClass=(self.eqv.other)
			end select
	end select
end function
end program