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POAsk for an example for the limitation of boost::bind()
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copied!<p>I read the explanation of the limitation at <a href="http://www.boost.org/doc/libs/1_49_0/libs/bind/bind.html#Limitations" rel="nofollow">http://www.boost.org/doc/libs/1_49_0/libs/bind/bind.html#Limitations</a> but I don't quite understand it. Can any body give me an example of that stated limitation, please?</p> <p>Let me ask this question in another way with this example:</p> <pre><code>#include <boost/bind.hpp> #include <boost/function.hpp> #include <iostream> #include <string> using namespace std; void Five(int &a, int &b, int &c, const int &d, const int &e) { cerr << "In Five(): " << a + b + c + d + e << endl; } int main() { int r = 1; const int c = 100; boost::bind(Five, _1, _2, _3, _4, _5)(r, r, r, c, r); boost::bind(Five, _1, _2, _3, _4, _5)(r, r, r, r, c); return 0; } </code></pre> <p>This code compiles just fine (without C++11 support). So, if bind even works in this case, what does "limitation" refer to? Any concrete examples, please?</p> <p>Another (better) example:</p> <pre><code>#include <boost/bind.hpp> #include <iostream> #include <string> using namespace std; void Two(int &a, const int &c) { cerr << "In Two(): " << a + c << endl; } void Three(int &a, int &b, const int &c) { cerr << "In Three(): " << a + b + c << endl; } int Fun() { return 3; } int main() { int r = 1; const int c = 100; boost::bind(Two, _1, _2)(r, Fun()); // 1. OK boost::bind(Three, _1, _2, _3)(r, r, c); // 2. OK Three(r, r, Fun()); // 3. OK boost::bind(Three, _1, _2, _3)(r, r, Fun()); // 4. CE!! //??? Why 2 is OK but 4 is not ??? return 0; } </code></pre>

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