问题
In C# the extern modifier is used to declare a method that is implemented externally. Usually it is used with DllImport attribute to call some function in unmanaged code.
I wonder if there is a way to provide custom implementation of extern method?
To understand better the problem consider the following use case. I have a set of functions implemented in unmanaged code and I'd like to supply pointers to these function in run-time (during the loading of assembly).
The same thing DllImport attribute does, but I'd like to provide pointers by myself.
回答1:
This is possible although you would need to PInvoke several things (LoadLibrary and GetProcAddress - see links below)... it is called "late binding native code"...
Some relevant links with source:
- http://blogs.msdn.com/b/junfeng/archive/2004/07/14/181932.aspx
- http://www.codeproject.com/KB/cs/dyninvok.aspx
- http://pinvoke.net/default.aspx/kernel32/GetPRocAddress.html
- http://www.pinvoke.net/default.aspx/kernel32.loadlibrary
回答2:
You would need to use LoadLibrary and GetProcAddress
来源：https://stackoverflow.com/questions/7245507/how-to-provide-custom-implementation-for-extern-methods-in-net