Re: Problem with threads

James Kanze <>
Sun, 24 Feb 2008 05:34:41 -0800 (PST)
yatko wrote:

I want to write a class as follows:

class Foo

   void Start(void);

   boost::thread* ptr;
   void Update(int x, int y);

     ptr = new boost::thread( boost::bind( &Update, x, y) ); //
compiler complains here

And what is boost::thread supposed to do with &Update? Update
is a non-static member function, and can only be called on an
object. Of type Foo. The only object you're giving
boost::thread is the result of boost::bind.

And of course, you can't take the address of a member function
like that anyway; the syntax would be &Foo::Update (even in a
member function of Foo).

You need is something like:

    boost::bind( &Foo::Update, this, x, y ) ;

All I want to do is creating a Foo object, initializing it
and creating a thread which is calling Update() member
function after calling Start() member function. However,
compiler complains and says that

"error: ISO C++ forbids taking the address of an unqualified
or parenthesized non-static member function to form a pointer
to member function."

Well, that's the obvious syntax error mentionned above. Once
you've resolved that, you still have to tell bind what object to
use when calling the member function.

It seems that creating a thread that calls a member function
is impossible, and called function must be static.

No, but you have to tell bind (and thus boost::thread) what
object to use. And you have to use the correct syntax for a
pointer to member.

(I modified your code so that start() took two arguments, x and
y, and with the suggested corrections, it worked for me.)

James Kanze (GABI Software)
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