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Re: RPC_METHOD how to "define" [message #47579 is a reply to message #47578]

Tue, 31 January 2017 22:10

dolik.rce
Messages: 1791
Registered: August 2008
Location: Czech Republic

Ultimate Contributor

Hi NilaT,

NilaT wrote on Tue, 31 January 2017 16:56

How do i extract that weird define?
#define RPC_METHOD(name) void name(RpcData& rpc); INITBLOCK { Register(#name, name); } void name(RpcData& rpc)
So in particular, how can I use the example method getClientList as a member function?
And whats INITBLOCK and #name?

First a little hint: In TheIDE open a file where RPC_METHOD is used and hit Build -> Preprocess (or Alt+F7). It will show you the file with all includes included and macros expanded.

Now, to decipher the macro:

The INITBLOCK is another U++ macro, which allows you to add a code block that will be executed when the program starts, before main() is executed. It is often used to register methods or plugins.

#name creates a string literal of the value passed to the name parameter. So the "RPC_METHOD(MyMethod){ some_code; }" expands to this:

void MyMethod(RpcData& rpc);
INITBLOCK {
    Register("MyMethod", MyMethod);
}

void name(RpcData& rpc) {
    some_code;
}

Note that I added some newlines for better readability. So what the macro does, step by step, is:
1) The function is declared.
2) It is registered, so that the RPC server knows that the method exists.
3) The function is defined. Here the code block that follows macro handily becomes the function body.

Does this explanation make it clearer?

To create the methods as class members, you'll have to do the same steps as the macro does, but with a member functions. That's is declare and/or define the member function and register it before it can be used. It would be probably ok to call Register in the class constructor. So it could look somewhat like this:

class MyRpcClass {
public:
    typedef MyRpcClass CLASSNAME;
    void MyMethod(RpcData& data);
    MyRpcClass() {
        Register("MyMethod", THISBACK(MyMethod));
    }
}

Warning: I haven't tested the code (and I'm not even familiar with how the RpcServer works internally), so it will probably need a bit more work Smile

But in general, it should be possible to do this.

Best regards,
Honza

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