member data pointer and nested bind
Hello,
I've been trying to use STL alogorithms on POD struct data member without
writing any user defined functor nor adding get/set member function to the
POD sturct, instead I just wanted to use boost::mem_fn, boost::bind,
boost::lambda for member data pointer.
It was fine to use the member data pointer with any of boost::mem_fn,
boost::bind and boost::lambda only until I tried to use them in the nested
bind as an argument of outter bind. If I use them in nested bind, I got
compile error message of "cannot convert parameter 1 from
'boost::_bi::bind_t
JaeWook Choi wrote:
vector<CTestClass>::iterator it_f1 = find_if(vecTestClass.begin(), vecTestClass.end(), bind(::PtInRect, &bind(&CTestClass::rc, _1), ptTest) ); // compile error!
You can't use &bind with boost::bind, only with boost::lambda::bind. If you want to keep using boost::bind: template<class T> struct address_of { typedef T* result_type; result_type operator()( T & t ) const { return &t; } }; vector<CTestClass>::iterator it_f1 = find_if(vecTestClass.begin(), vecTestClass.end(), bind( ::PtInRect, bind( address_of<RECT>(), bind(&CTestClass::rc, _1) ), ptTest ) ); If you switch to lambda::bind you might have problems with the __stdcall convention that PtInRect uses; bind<BOOL>( ::PtInRect, ... ) might get you around that.
Hello Peter,
Thank you so much. It seems both solutions are working well.
BTW, Is there any links that explain the differences /or commons between
boost::bind & boost::lambda::bind in their usage? It isn't quite easy for a
newbie to look through boost source code to figure all that.
Thanks again.
Jae.
----- Original Message -----
From: "Peter Dimov"
JaeWook Choi wrote:
vector<CTestClass>::iterator it_f1 = find_if(vecTestClass.begin(), vecTestClass.end(), bind(::PtInRect, &bind(&CTestClass::rc, _1), ptTest) ); // compile error!
You can't use &bind with boost::bind, only with boost::lambda::bind. If you want to keep using boost::bind:
template<class T> struct address_of { typedef T* result_type; result_type operator()( T & t ) const { return &t; } };
vector<CTestClass>::iterator it_f1 = find_if(vecTestClass.begin(), vecTestClass.end(), bind( ::PtInRect, bind( address_of<RECT>(), bind(&CTestClass::rc, _1) ), ptTest ) );
If you switch to lambda::bind you might have problems with the __stdcall convention that PtInRect uses; bind<BOOL>( ::PtInRect, ... ) might get you around that.
JaeWook Choi wrote:
Hello Peter,
Thank you so much. It seems both solutions are working well. BTW, Is there any links that explain the differences /or commons between boost::bind & boost::lambda::bind in their usage?
There is http://www.boost.org/doc/html/lambda/s08.html#id2713474 but it doesn't seem to address neither of the questions you raised in your previous post. It should be possible to deduce most of the differences between lambda::bind and boost::bind by reading the documentation of the two libraries. For example, & doesn't work with boost::bind because boost::bind is not a "lambda" library and doesn't support operators (except for a very limited subset: http://www.boost.org/libs/bind/bind.html#operators that is a recent addition.) Lambda, on the other hand, doesn't support the boost::bind macro BOOST_BIND_ENABLE_STDCALL, however if you read http://www.boost.org/libs/bind/bind.html#Q_win32_api you'll see that it suggests an alternative of using bind<R>(...), so it makes sense to try it with lambda::bind and see whether it works. :-) Ideally, lambda::bind would be a superset of boost::bind, but for various reasons this is not the case today; at some point we probably need to accept this sad fact and write a page that lists all differences between the two.
Hello Peter,
Thank you so much. It seems both solutions are working well.
BTW, Is there any links that explain the differences /or commons between
boost::bind & boost::lambda::bind in their usage? It isn't quite easy for a
newbie to look through boost source code to figure all that.
Thanks again.
Jae.
----- Original Message -----
From: "Peter Dimov"
JaeWook Choi wrote:
vector<CTestClass>::iterator it_f1 = find_if(vecTestClass.begin(), vecTestClass.end(), bind(::PtInRect, &bind(&CTestClass::rc, _1), ptTest) ); // compile error!
You can't use &bind with boost::bind, only with boost::lambda::bind. If you want to keep using boost::bind:
template<class T> struct address_of { typedef T* result_type; result_type operator()( T & t ) const { return &t; } };
vector<CTestClass>::iterator it_f1 = find_if(vecTestClass.begin(), vecTestClass.end(), bind( ::PtInRect, bind( address_of<RECT>(), bind(&CTestClass::rc, _1) ), ptTest ) );
If you switch to lambda::bind you might have problems with the __stdcall convention that PtInRect uses; bind<BOOL>( ::PtInRect, ... ) might get you around that.
Hello Peter,
Thank you so much. It seems both solutions are working well.
BTW, Is there any links that explain the differences /or commons between
boost::bind & boost::lambda::bind in their usage? It isn't quite easy for a
newbie to look through boost source code to figure all that.
Thanks again.
Jae.
"Peter Dimov"
JaeWook Choi wrote:
vector<CTestClass>::iterator it_f1 = find_if(vecTestClass.begin(), vecTestClass.end(), bind(::PtInRect, &bind(&CTestClass::rc, _1), ptTest) ); // compile error!
You can't use &bind with boost::bind, only with boost::lambda::bind. If you want to keep using boost::bind:
template<class T> struct address_of { typedef T* result_type; result_type operator()( T & t ) const { return &t; } };
vector<CTestClass>::iterator it_f1 = find_if(vecTestClass.begin(), vecTestClass.end(), bind( ::PtInRect, bind( address_of<RECT>(), bind(&CTestClass::rc, _1) ), ptTest ) );
If you switch to lambda::bind you might have problems with the __stdcall convention that PtInRect uses; bind<BOOL>( ::PtInRect, ... ) might get you around that.
participants (2)
-
JaeWook Choi -
Peter Dimov