Using boost bind to access member function of inner class

Question

I'm trying to access a member function of a nested class in a find_if expression.

My code below causes a compile error in the bind expression - (‘COuter::innerClass’ is not a class or namespace).

Could you help me with the correct bind expression?

vector<COuter> vec; vec.push_back(COuter()); vector<COuter>::const_iterator it = find_if(vec.begin(), vec.end(), bind(&COuter::innerClass::GetTemp, _1) == 42);

My example classes:

class CInner { public: CInner() : _temp(42) {}; int GetTemp() const { return _temp; } private: int _temp; }; class COuter { public: CInner innerClass; };

Maxim Egorushkin · Accepted Answer · 2011-01-12 15:27:59Z

3

Correct expression is bind(&CInner::GetTemp, bind(&COuter::innerClass, _1)).

edited Jan 12, 2011 at 15:27

answered Jan 12, 2011 at 15:22

Maxim Egorushkin

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3 Comments

CashCow Over a year ago

What is this extra bind doing there? You should just pass in a reference to the member.

Maxim Egorushkin Over a year ago

@CashCow: you need an extra bind to traverse through the extra object innerClass. It works as it should with gcc-4.4.

Rob Kennedy Over a year ago

@CashCow, the desired ordinary-C++ expression is this: vec[i].innerClass.GetTemp() == 42. The _1 variable will refer to vec[i], so the inner bind expression gives us a reference to vec[i].innerClass. The outer bind gets us its GetTemp member.

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