Databases
StackOverflow2013
Postsdbo
POHow do I implement a callback in C++?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POHow do I implement a callback in C++?
    primarykey
    data
    text
    <p>I want to implement a class in c++ that has a callback. </p> <p>So I think I need a method that has 2 arguments:</p> <ul> <li>the target object. (let's say *myObj)</li> <li>the pointer to a member function of the target object. (so i can do *myObj->memberFunc(); )</li> </ul> <p>The conditions are:</p> <ul> <li><p>myObj can be from any class.</p></li> <li><p>the member function that is gonna be the callback function is non-static. </p></li> </ul> <p>I've been reading about this but it seems like I need to know the class of myObj before hand. But I am not sure how to do it. How can I handle this? Is this possible in C++?</p> <p>This is something I have in mind but is surely incorrect.</p> <pre><code>class MyClassWithCallback{ public void *targetObj; void (*callback)(int number); void setCallback(void *myObj, void(*callbackPtr)(int number)){ targetObj = myObj; callback = callbackPtr; }; void callCallback(int a){ (myObj)-&gt;ptr(a); }; }; class Target{ public int res; void doSomething(int a){//so something here. This is gonna be the callback function}; }; int main(){ Target myTarget; MyClassWithCallback myCaller; myCaller.setCallback((void *)&amp;myTarget, &amp;doSomething); </code></pre> <p>}</p> <p>I appreciate any help. </p> <p>Thank you.</p> <p>UPDATE Most of you said Observing and Delegation, well that's i exactly what i am looking for, I am kind of a Objective-C/Cocoa minded guy. My current implementation is using interfaces with virtual functions. Is just I thought it would be "smarter" to just pass the object and a member function pointer (like boost!) instead of defining an Interface. But It seems that everybody agrees that Interfaces are the easiest way right? Boost seems to be a good idea, (assuming is installed)</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USnacho4d
    1. USnacho4d
    plurals
    1. This table or related slice is empty.
    1. PL
      singulars
      1. LTLinked
    2. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POHow do I implement a callback in C++?
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POHow do I implement a callback in C++?
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POHow do I implement a callback in C++?
      1. This table or related slice is empty.
      1. VTUpMod
    1. COObserver pattern requires changes in "observed" class interface, sometimes it is much simpler and clearer use `function` and `bind` instead of interfaces. Also note, if you using recent gcc, you already have `function` and `bind` so no need of boost. Using function/bind is functional programing patters while using interfaces is more using "standard" design pattern that has different meaning
      singulars
      1. POHow do I implement a callback in C++?
      1. USArtyom
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload