The G2 preprocessor

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  • Introduction

    The title of this page is deceptive: "G2" is not a preprocessor, it's not even a tool. It is mainly an idea, a strategy. This idea can be explained very simply: With only a small and simple tool, you can turn any existing language into a text preprocessor. The g2pp tool proposed on these pages, implements this idea for one specific case: it lets TCL act as a preprocessor language for C++. The documentation of the tool often reminds you that the same idea can also easily be implemented for other combinations of languages.

    When developing C++ applications, I have often bumped into the limitations of the C preprocessor. Sure, it has #define and #if, but why doesn't it have loops, lists, arrays, procedures, objects, file I/O and more? I would like my preprocessor to take over much of the boring, repetitive and non-creative effort of C++ programming, like managing member variables, writing a copy constructor and assignment operator, making objects persistent on disk, etc. That's the itch I'm trying to scratch.

    Rather than inventing a new preprocessor language (which would imply a steeper learning curve and a lot more development effort), I have chosen to use TCL as the preprocessor language for C/C++. The flexibility and extensibility of TCL are the main reasons for this choice; if you want, you can easily adapt most of the ideas for use with other languages (Python, Perl, Ruby, ...).

    Download area

    The following information is available for you to download:

    • Documentation about the tool's purposes and concepts, including lots of examples.
    • g2pp-0.6.tgz: Tarball with the sources, the documentation, and many examples that you can immediately run and experiment with.
      Includes TCL sources for clipboards, C++ generation, and roles.
      Implemented and tested on Linux; requires a sufficiently recent version of TCL (8.2 will do).