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POC++ unpack/unbox class method arguments
 

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  1. POC++ unpack/unbox class method arguments
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    <p>I have a a bunch of subclasses each with static class factory methods of varying argument numbers and types, and would also like to instantiate them from data loaded via a json data file using <a href="http://jsoncpp.sourceforge.net/" rel="nofollow noreferrer">jsonpp</a>.</p> <p>So say I'll have an array of Json::Value objects for the arguments, is there a smart way, using macros or something in c++ to create alternate proxy methods that accepts the Json::Value array and calls the original method, e.g.)</p> <pre><code>Foo* Foo::create(int a, const char* b) { /* ... */ } Foo* Foo::create(Json::Value args) { //the Json::Value args represents an array value here // can I avoid having to manually create each of these Json methods? return Foo::create(args[0].asInt(), args[1].asCString()); } </code></pre> <p>Sorry, my c++ is still getting up to speed. I've found a few topics that seem to deal with unpacking tuple arguments for example,</p> <ul> <li><a href="https://stackoverflow.com/questions/10766112/c11-i-can-go-from-multiple-args-to-tuple-but-can-i-go-from-tuple-to-multiple?lq=1">C++11: I can go from multiple args to tuple, but can I go from tuple to multiple args?</a></li> <li><a href="https://stackoverflow.com/questions/687490/how-do-i-expand-a-tuple-into-variadic-template-functions-arguments">How do I expand a tuple into variadic template function&#39;s arguments?</a></li> <li><a href="https://stackoverflow.com/questions/11044504/any-solution-to-unpack-a-vector-to-function-arguments-in-c">Any Solution to Unpack a Vector to Function Arguments in C++?</a></li> </ul> <p>but I am unsure of which approach to proceed with. Thanks for the help</p>
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    1. USmagoo
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    1. CODo you have access to C++11 or C++03? C++11 had methods of handling this. If you only have C++03, then you will have to do a lot of the work yourself.
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      1. USCort Ammon
    2. COHi Cort, yes, I am compiling with C++11
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      1. USmagoo
    3. COYou stated you load some data from a file and use it to instantiate some classes. If the number of arguments (or their types) for this `create` function call is dependent on the loaded data, then there's no sane way to do it. Templates are "resolved" at compile-time, which means to use a pack expansion, the types and number of arguments must be known at compile-time.
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