Executable Programs

Gamma: Version 4.0
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# 2.2. Executable Programs

There is currently no facility for embedding Gamma source code into a stand-alone Gamma executable. However, it is possible to create a Gamma program which appears to be a stand-alone executable to the user. This is done by using the shell's #! directive at the top of the Gamma file. Simply include the line indicating the full path for your Gamma program, for example:

        #!/usr/cogent/bin/gamma

If using Gamma with Photon, you should use:

        #!/usr/cogent/bin/phgamma

Then change the permissions on the Gamma file to be executable. The Gamma file can now be run directly as if it were a stand-alone executable. The directive must appear as the first line of the program, and it must reference the actual Gamma executable, not a link.

The following example program will print the famous "Hello world" message to the screen:

        #!/usr/cogent/bin/gamma

        princ ("Hello world\n");

There is no requirement for a function named `main`. If a function with the name `main` is defined, then Gamma automatically starts to execute that function. Thus, the result of the following program:

        #!/usr/cogent/bin/gamma

        function MyPrint()
        {
            princ ("Hello world\n");
        }

        function main()
        {
            MyPrint();
        }

        MyPrint();

is that the function `MyPrint` will be executed twice.

Command line arguments can be passed to the Gamma program using the list variable `argv`. For more details see Tutorial I.

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