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POMetaprogramming C/C++ using the preprocessor
 

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    <p>So I have this huge tree that is basically a big switch/case with string keys and different function calls on one common object depending on the key and one piece of metadata.</p> <p>Every entry basically looks like this</p> <pre><code>} else if ( strcmp(key, "key_string") == 0) { ((class_name*)object)-&gt;do_something(); } else if ( ... </code></pre> <p>where <code>do_something</code> can have different invocations, so I can't just use function pointers. Also, some keys require object to be cast to a subclass.</p> <p>Now, if I were to code this in a higher level language, I would use a dictionary of lambdas to simplify this.</p> <p>It occurred to me that I could use macros to simplify this to something like</p> <pre><code>case_call("key_string", class_name, do_something()); case_call( /* ... */ ) </code></pre> <p>where <code>case_call</code> would be a macro that would expand this code to the first code snippet.</p> <p>However, I am very much on the fence whether that would be considered good style. I mean, it would reduce typing work and improve the DRYness of the code, but then it really seems to abuse the macro system somewhat. </p> <p>Would you go down that road, or rather type out the whole thing? And what would be your reasoning for doing so?</p> <p><strong>Edit</strong></p> <p>Some clarification:</p> <p>This code is used as a glue layer between a simplified scripting API which accesses several different aspects of a C++ API as simple key-value properties. The properties are implemented in different ways in C++ though: Some have getter/setter methods, some are set in a special struct. Scripting actions reference C++ objects casted to a common base class. However, some actions are only available on certain subclasses and have to be cast down.</p> <p>Further down the road, I may change the actual C++ API, but for the moment, it has to be regarded as unchangeable. Also, this has to work on an embedded compiler, so boost or C++11 are (sadly) not available.</p>
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    1. COWhy the votes to close - this is a very good, valid question. What am I missing here?
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      1. USMichael Dorgan
    2. COIt's a nice question, but "This question is not a good fit to our Q&A format. We expect answers to generally involve facts, references, or specific expertise; *this question will likely solicit opinion, debate, arguments, polling, or extended discussion.*"
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    3. COIt's already at +5 score, so that kinda says that others, myself included, are interested in the result. The answer below is already pretty nice.
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