1. A method for performing conditional compilation, the method comprising: analyzing a programming language file prior to compilation to locate a preprocessing directive that specifies a condition to be evaluated and identifies source code to be conditionally included during a subsequent compilation of the programming language file; generating evaluation source code that evaluates the condition; evaluating the condition by evaluating run-time variables within the evaluation source code, wherein the run-time variables are also available at run-time during execution of a compiled version of the programming language file; creating a modified programming language file by conditionally including source code associated with the evaluation of the condition; and compiling the modified programming language file.