Static array of method pointers

Question

I'm facing an error I dont understand.

I try to create and use a static array of method pointers. The declaration in my class looks like this:

static void (Client::*packetHandler[Op::handledOpcodeMax - Op::handledOpcodeMin + 1])(QByteArray &data);

Initialization takes place in my .cpp files is like that:

void (Client::*packetHandler[Op::handledOpcodeMax - Op::handledOpcodeMin + 1])(QByteArray &data);

Here comes the troubles, in one of my Client's class method I try to use this methods pointers' array. I tried several ways, for example :

(this->*packetHandler[_opcode])(data);

I said I didnt understand the problem, let me explain why. Running make on my code results in a proper compilation, tought, there is a problem when linking.

client.cpp:71: undefined reference to `Client::packetHandler'

This message is repeated 5 times.

Any help would be welcome. Thank you.

statics are local to your translation unit. maybe an export would be in order. — Captain Giraffe
– Captain Giraffe, Commented Sep 22, 2011 at 19:57
would it be too obnoxious to tell you to use boost::function instead ? — George Godik
– George Godik, Commented Sep 22, 2011 at 19:58
I would strongly recommend a few typedefs to clean up that mess. — Kerrek SB
– Kerrek SB, Commented Sep 22, 2011 at 19:58
is there any chance few of the lines exists in a header file ? — stdcall
– stdcall, Commented Sep 22, 2011 at 20:02
@KerrekSB typedefs would make those cleaner, but not so funny. — rodrigo
– rodrigo, Commented Sep 22, 2011 at 20:08

Neil · Accepted Answer · 2011-09-22 20:33:09Z

3

void (Client::*packetHandler[Op::handledOpcodeMax - Op::handledOpcodeMin + 1])(QByteArray &data); declares a global variable named packetHandler. You want to define your class variable, which needs an extra Client:: like so:

void (Client::*Client::packetHandler[Op::handledOpcodeMax - Op::handledOpcodeMin + 1])(QByteArray &data);

answered Sep 22, 2011 at 20:33

Neil

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2 Comments

Xaqq Over a year ago

Haha thank you Neil. I was thinking of something like this after @thekashyap comment. I tried void (Client::Client::*packetHandler[Op::handledOpcodeMax - Op::handledOpcodeMin + 1])(QByteArray &data);. Bad luck with * position :D. Thanks :)

Kashyap Over a year ago

Just goes to show how important Kerrek SB's comment abt typedefing is.. :)

Sean · Accepted Answer · 2011-09-22 20:12:26Z

0

Client::*packetHandler is a member function pointer that points to a member function named Client::packetHandler. I'm not sure how to make a member function pointer that points to an arbitrary member function which is what you seem to want to do. I think George is right. You should consider using something like boost::function or std::tr1::function or write your own member function wrapper class.

answered Sep 22, 2011 at 20:12

Sean

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1 Comment

Xaqq Over a year ago

To make a function pointer pointing to whatever member function you want is simple, you have nothing special to do. My problem here is that I want this array to be a static element of my class. Removing the static keyword in the header file makes the compilation and linking work.

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