晚期绑定与未知参数 [英] C late binding with unknown arguments

问题描述

我目前正处于一个需要调用很多在运行时提取的函数指针的情况。问题是在编译时参数是未知的。

但是，在运行时，我收到的数据可以让我知道这个函数的参数，甚至可以存储char *数组中的参数。问题是我没有一个函数指针模型来转换。

在高级语言中，我知道有一些函数，如InvokeMethode（String name， Byte [] args）解释字节数组，如参数。因为C中不存在反射，所以我没有希望看到这个函数指针。

我想到的一个解决方案（真的很糟糕）在编译时创建一个函数指针的模型，将以hardcoded方式将ptr转换为正确的类型，使用如下：

  void callFunc64Bits（void * funcPtr，long long args）; 
 void callFuncVoid（void * funcPtr）; 
  

问题是我必须创建像这样的100个函数才能正确地转换指针。

有更好的方法吗？

非常感谢！

解决方案

这是一个难题没有，不幸的是，好的或简单的答案。

看到这个以前的问题： gcc（反向va_args / varargs）中的运行时参数

看到这个C常见问题： http://c-faq.com/varargs/invvarargs.html

请通过C常见问题列表维护者查看wacky ideas的集合： http://c-faq.com/varargs/wacky.html

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附录：请参阅以前的SO问题：如何通过传递多个参数的指针来调用函数在C？中

...其中提到libffi： http://sourceware.org/libffi/

I am presently in a case where I need to call a lot of function pointers that has been extracted at runtime. The problem is that the arguments are unknown at compilation time.

But, at runtime I receive datas that allows me to know the arguments of the function and I can even store the arguments in a char* array. The problem is that I don't have a function pointer model to cast it into.

In high level language, I know there is function like "InvokeMethode(String name,Byte[] args)" that interpret the bytes array like arguments. Since reflection does not exist in C, I have no hope to see this with a function pointer.

One solution that I have in mind (and it's really bad), is to create a model of function pointer at compilation time that will cast in a "hardcoded way" the ptr to the right type to use like this:

void callFunc64Bits(void* funcPtr,long long args);
void callFuncVoid(void* funcPtr);

The problem is that I will have to create like 100 function like this that will cast the pointer correctly.

Is there a way to do it more efficiently?

Thank you very much!

解决方案

This is a hard problem without, unfortunately, good or easy answers.

See this former SO question: Run-time parameters in gcc (inverse va_args/varargs)

See this C FAQ question: http://c-faq.com/varargs/invvarargs.html

See this collection of "wacky ideas" by the C FAQ list maintainer: http://c-faq.com/varargs/wacky.html

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Addendum: see this former SO question: How to call functions by their pointers passing multiple arguments in C?

...which mentions "libffi": http://sourceware.org/libffi/

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