Modules

A method exists for interfacing with C++ DLLs. The syntax of declaring a C++ module is shown below.

module module_name
{
 ...
}

Inside the module declaration the signatures of the C++ functions are declared. An example of this is shown below.

An Example of Modules

A program that interfaces with a C++ dll is shown below.

// testC.txt - Testing modules.

space TestC
{
    module TestC
    {
       test()
       test_double(d)
       test_string(s)
       test_pointer(p)
    }

    Test()
    {
        m = new TestC()
        m.test()
        r = m.test_double(20.5)
        cout << "return = " << r << "\n"
        r = m.test_string("hello world")
        p = 8
        p.allocate()
        p[0] = 100
        r = m.test_pointer(p)
        cout << "return = " << r << "\n"
        cout << "updated integer = " << p[0] << "\n"
        p.close()
    }
}

The output of the program is shown below.

In test
In test_double, parameter = 20.5
return = 100
In test_string, parameter = hello world
In test_pointer, parameter = 100 updating it to: 1000
return = 100
updated integer = 1000

The C++ source code of the module TestC is shown below.

#include<iostream>

extern "C"
{
	__declspec(dllexport) long long test()
	{
		std::cout << "In test\n";
		return 20;
	}

	__declspec(dllexport) long long test_int(long long l)
	{
		std::cout << "In test_int, parameter = " << l << "\n";
		return 100;
	}


	__declspec(dllexport) long long test_double(double* d)
	{
		std::cout << "In test_double, parameter = " << *d << "\n";
		return 100;
	}

	__declspec(dllexport) long long test_string(const wchar_t* s)
	{
		std::wcout << L"In test_string, parameter = " << s << L"\n";
		return 100;
	}

	__declspec(dllexport) long long test_pointer(int* i)
	{
		std::cout << "In test_pointer, parameter = " << *i <<  " updating it to: 1000\n";
		*i = 1000;
		return 100;
	}
}

Note that integers are passed as value types in the form of "long long". When a decimal number is passed, it is represented by the datatype "double*". You may update the double to which the parameter points to. Strings are passed as "const wchar_t*" and they should not be updated. To pass an arbitary pointer to data, you allocate the data on the heap using the method of the integer class: allocate(). Any type of data may be allocated and passed in this way. In the above example, a 64 bit integer is allocated and passed to the C++ function test_pointer. The integer is updated by the C++ function and the updated integer is printed by the Generic function.

This is a limited interface and the datatypes used in the C++ module must be 64 bit. A maximum of 15 parameters are supported.