C++ - Thread - Pointer to function!

Your problem is the function pointer.

For Windows, your thread function you supply to CreateThread must be:
You can write any function BUT the function must have an LPVOID argument and return a DWORD. If it doesn't, then it can't be used as a thread.

Read the pthread_create() documentation clearly and focus on the type of function pointer required. You may need to type cast your function to the correct type.

Your problem is the function pointer.

For Windows, your thread function you supply to CreateThread must be:
[code=cpp]
DWORD WINAPI THreadProc(LPVOID);
[/cpp]

You can write any function BUT the function must have an LPVOID argument and return a DWORD. If it doesn't, then it can't be used as a thread.

Read the pthread_create() documentation clearly and focus on the type of function pointer required. You may need to type cast your function to the correct type.

I am working with linux.

I just have one question: what is the correct syntax to call a method with function pointer as an argument in pthered_create?

forexample when I define this like:

pthread_create( &receiveThread, NULL, EventInterface::receiveEvent, (void *) (*ptToFunc))

or

pthread_create( &receiveThread, NULL, EventInterface::receiveEvent, (void *) ptToFunc)


I have this error:

error: invalid conversion from 'void* (*)(void (*)(Event*, int))' to 'void* (*)(void*)'

pthread_create has this prototype:

The start routine is:

void *(*start_routine)(void*)

That is, start_routine is a pointer to a function with a void* argunment that returns a void*.

Your function must have thisprototype.

However, this function:
does not have a void* argument and does not return a void*. So you can't use this function as a thread.

Yout could use:
This is exactly the procedure I outlined in the Windows eaxmple. The OS function cannot accommodate just any old function. It has to be of a pre-defined format.

Inside MyFunction(void* arg) you know the arg is an Event* so it is safe to type cast the void* to an Event* and off you go.

I guess I find a way to solve the problem.


However now I see some warning like:

ISO C++ forbids casting between pointer-to-function and pointer-to-object

for those lines I showed by *.

Do you have any idea?

Did you read Post #5??

Did you read Post #5??

actually I read that after I post my new post!

The problem is the name of call back function is called from EventInterface constructor. so how could it be possible with your solution?!

maybe I need to read your solution more accurately.

for those who might see this thread then... I finally come up with a syntax which WORKS!

I just wrap my pointer to function in an struct!\

for those who might see this thread then... I finally come up with a syntax which WORKS!

I just wrap my pointer to function in an struct!\

Expand|Select|Wrap|Line Numbers

1.  
2. class EventInterface 
3. {
4.  
5. public:
6.  
7.     typedef struct{
8.         void (*onMessageFunction)(Event*, int);
9.     } callBackFunc;
10.  
11.     EventInterface(callBackFunc);
12.         ...
13.     static void * receiveEvent (void *);
14.  
15. }
16.  
17. EventInterface::EventInterface(callBackFunc ptToFunc){
18.  
19.     pthread_create( &receiveThread, NULL, EventInterface::receiveEvent, (void *) &ptToFunc)
20.  
21. }
22.  
23. void * EventInterface::receiveEvent(void * arg){
24.  
25.     callBackFunc * onMessageFunc;
26.     onMessageFunc= (callBackFunc*) arg;
27.  
28.        .....
29.  
30.        onMessageFunc->onMessageFunction(notifiedEvent , subscriptionID);
31. }
32.  
33.  

Don't do it. It will mess up. Get rid of the address operator. You are passing the address of where the callback pointer is stored on the stack.
.


Adrian