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Problems using Class Methods as Callbacks.

asked 2012-12-07 10:05:50 -0500

Ammar gravatar image

Hi All, I have a weird issue that I am facing while using class methods as callbacks. I am going to try and summarize the issue here.

class A{
   int alpha;
class B:public A{ 
   B(){ alpha = 1; }
   void some_func(){ alpha = 2; }
   void odom_callback(const nav_msgs::Odometry::ConstPtr& msg){ std::cout<<alpha;}
int main(){
B * var = new B;
B->some_ func();

Now, when the odom callback is called, I would expect it to print 2 for the value of alpha. However, in the callback it keeps printing 1. I know for sure that some_func() has been called. However I do not know why in the callback it uses the first initialized value. Of course my real code is more complex, though I tried to illustrate the fault in this example. Please let me know what you think might be going wrong. Thanks! Ammar

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Try making your example more realistic, i.e. a real node that can compile, with a real subscriber, etc. and test it. It should work as expected. Meaning that your real and more complex code has a different issue. But try this first.

brice rebsamen gravatar image brice rebsamen  ( 2012-12-07 11:54:09 -0500 )edit

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answered 2012-12-07 12:40:02 -0500

I assume you meant:

B * var = new B;
var->some_ func();

ant not

B * var = new B;
B->some_ func();

As brice suggested, post the real example which is failing, or a link to it and a description of the relevant lines.

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Asked: 2012-12-07 10:05:50 -0500

Seen: 216 times

Last updated: Dec 07 '12