C++ when i try get string, it always empty, lambda - c++

Question

I have object of class
class MenuItem {
public:
void updateInputText(string text)
{
this->text += text;
}
string getText() const {
return this->text;
}
void trigger(Event event)
{
switch (event) {
case ENTER:
this->onEnterAction();
break;
}
}
function<void(void)> onEnterAction;
private:
Text text;
void onEnter();
};
I create object and set event handler
MenuItem IP;
IP.onEnterAction = eventOnEnter;
// ENTER - element from enum
IP.trigger(ENTER);
Event handler:
function<void(void)> eventOnEnter = [&] () {
auto selected = next(this->currentMenu.begin(), this->selected);
selected->updateInputText("Hello");
};
And second object of MenuItem
MenuItem nextButton;
next.onEnterAction = [&] () {
Log::write("IP: " + IP.getText());
};
// ENTER - element from enum
next.trigger(ENTER);
But IP.getText() always empty. What i do wrong?
All objects created in one scope (in one function)

Answer 1

Whenever I see something like this
MenuItem nextButton;
next.onEnterAction = [&] () { // Should next be nextButton???
Log::write("IP: " + IP.getText());
};
// ENTER - element from enum
next.trigger(ENTER);
I'm waiting for a disaster to occur. And if you had shown a fully working example you would have noted that your example code might have worked ... so what is the problem.
The main problem is that you capture everything by reference, but from your code I can't se if it should work, but I think not in a large system, the reason is that the captured values have gone out of scope.
std::vector<MenuItem> CreateMenu() {
std::vector<MenuItem> res;
function<void(void)> eventOnEnter = [&] () {
auto selected = next(this->currentMenu.begin(), this->selected);
selected->updateInputText("Hello");
};
MenuItem IP;
IP.onEnterAction = eventOnEnter;
res.push_back(IP);
MenuItem nextButton;
nextButton.onEnterAction = [&] () {
Log::write("IP: " + IP.getText());
};
res.push_back(nextButton);
return res;
}
void Call() {
auto buttons = CreateMenu();
// what is captured at this point???
buttons.back().trigger(ENTER);
}
Most of the captured has now gone out of scope.

Answer 2

Surt gave me a hint... Scope.
All MenuItems pushed to vector, and when i use this function
next.onEnterAction = [&] () {
Log::write("IP: " + IP.getText());
};
I try to get text from empty variable, when i changed function to
next.onEnterAction = [&] () {
auto selectedIP = std::next(currentMenu.begin(), 0);
Log::write("IP: " + selectedIP.getText());
};