CODEWITHSUNDEEP
c++boostlambdaboost-signals2
Min Lin
Min Lin

Reputation: 3197

boost signals auto disconnect lambda slot

I'm trying to do this:

boost::signals::connection c = somesignal.connect(
[c]()->void{
    // Do something
    c.disconnect();
})

Will this cause problems?

The connection c is assigned only after connect.

lambda needs to be initialized before connect.

It seems capture by value would not work. However, I can not capture by reference, since c is only a local variable.

If it is not a lambda, I can capture the "somesignal", and call somesignal.disconnect(slot). But in the case of a lambda, the slot is itself.

Upvotes: 1

Views: 1720

Answers (1)

Igor R.
Igor R.

Reputation: 15075

Use extended slot, Signals2 passes the connection object to it. It's designed primarily for thread-safety, but you can utilize it for your purposes as well:

somesignal.connect([](const connection &c)->void 
{
  // Do something
  c.disconnect();
});

(By the way, as opposed to what the title implies, it's actually not an "auto-disconnection", but the manual one. To disconnect slots automatically, one could use the tracking mechanism.)

Upvotes: 1

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