Re: Using function pointers in c++

From:
red floyd <no.spam@here.dude>
Newsgroups:
comp.lang.c++
Date:
Wed, 21 Feb 2007 18:37:40 GMT
Message-ID:
<Uj0Dh.8$BE2.6@newssvr27.news.prodigy.net>
MattWilson.6185@gmail.com wrote:

Hi!

I have had this problem several times before, and each time I have
been turned back forced to find another way. But not this time...

How can you cast a Class::* into a void *.

For this example I am using pthread and to start a thread you need to
pass it a void* (*)(void*)

however I have the run function inside a class:

class ThreadBase {
 public:
  ThreadBase() {}
  virtual void run() = 0;
  void start_thread() { pthread_create( &__thread_id , 0 ,this-

run , 0 ); }

  void join_thread();
 private:
  pthread_t __thread_id;
};

Now if you inherit from this class and make a run function and call
start_thread you recieve this error:

error: cannot convert void (ThreadBase::*)() to void* (*)(void*)

This doesn't only happen with classes, if you put a function in a
namespace I believe you get a similar error.

Is there a solution, or must you solve the problem another way?


In short, you can't, nor do you want to.

http://www.parashift.com/c++-faq-lite/pointers-to-members.html#faq-33.2

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