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From: David Greene (greened_at_[hidden])
Date: 2006-01-11 13:27:25

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Hi again,

As can can probably guess, I'm just learning how to use the BLL.

Here's another testcase I'm having trouble with:

#include <boost/lambda/lambda.hpp>
#include <boost/lambda/bind.hpp>
#include <boost/iterator/counting_iterator.hpp>

#include <vector>
#include <algorithm>
#include <cassert>

class Test {
private:
int value;

public:
Test(int v) : value(v) {};

int get(void) const { return(value); };
};

std::vector<Test> seq;

std::vector<Test>::iterator find_value(const Test &value)
{
using boost::lambda::bind;
using boost::lambda::_1;

return(std::find(seq.begin(), seq.end(),
bind(&Test::get, _1) == value.get()));
}

int main(void)
{
   std::copy(boost::counting_iterator<int>(0),
             boost::counting_iterator<int>(10),
             std::back_inserter(seq));

std::vector<Test>::iterator i = find_value(0);

assert(i == seq.begin());

i = find_value(5);

assert(i != seq.end());

i = find_value(11);

assert(i == seq.end());

return(0);
}

[compile log below]

Another question: when using bind to delay application of the member
function to the object, is the object passed by reference or value
on invocation? If by value, is there a way to pass it by reference?

It's not relevant to this test but will be in the code I'm
working on. I'm thinking of cases where I might want to
run transform algorithms on Test objects.

Thanks for your help. Some of this is just learning to pattern-match
gcc's cryptic template error messages.

-Dave

-------------------
/usr/include/c++/3.3.3/bits/stl_algo.h: In function `_RandomAccessIter
   std::find(_RandomAccessIter, _RandomAccessIter, const _Tp&,
   std::random_access_iterator_tag) [with _RandomAccessIter =
   __gnu_cxx::__normal_iterator<Test*, std::vector<Test,
std::allocator<Test> >
>, _Tp =

boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::relational_action<boost::lambda::equal_action>,
boost::tuples::tuple<const int,

boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<2,
   boost::lambda::function_action<2, boost::lambda::detail::unspecified> >,
   boost::tuples::tuple<int (Test::*const)() const, const
   boost::lambda::lambda_functor<boost::lambda::placeholder<1> >,
   boost::tuples::null_type, boost::tuples::null_type,
   boost::tuples::null_type, boost::tuples::null_type,
   boost::tuples::null_type, boost::tuples::null_type,
   boost::tuples::null_type, boost::tuples::null_type> > >,
   boost::tuples::null_type, boost::tuples::null_type,
   boost::tuples::null_type, boost::tuples::null_type,
   boost::tuples::null_type, boost::tuples::null_type,
   boost::tuples::null_type, boost::tuples::null_type> > >]':
/usr/include/c++/3.3.3/bits/stl_algo.h:298: instantiated from
`_InputIter std::find(_InputIter, _InputIter, const _Tp&) [with
_InputIter = __gnu_cxx::__normal_iterator<Test*, std::vector<Test,
std::allocator<Test> > >, _Tp =
boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::relational_action<boost::lambda::equal_action>,
boost::tuples::tuple<const int,
boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<2,
boost::lambda::function_action<2, boost::lambda::detail::unspecified> >,
boost::tuples::tuple<int (Test::*const)() const, const
boost::lambda::lambda_functor<boost::lambda::placeholder<1> >,
boost::tuples::null_type, boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type> > >,
boost::tuples::null_type, boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type> > >]'
lambda2.cc:28: instantiated from here
/usr/include/c++/3.3.3/bits/stl_algo.h:208: error: could not convert `
   boost::lambda::operator==(const A&, const
   boost::lambda::lambda_functor<Arg>&) [with A = Test, Arg =

boost::lambda::lambda_functor_base<boost::lambda::relational_action<boost::lambda::equal_action>,
boost::tuples::tuple<const int,

boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<2,
   boost::lambda::function_action<2, boost::lambda::detail::unspecified> >,
   boost::tuples::tuple<int (Test::*const)() const, const
   boost::lambda::lambda_functor<boost::lambda::placeholder<1> >,
   boost::tuples::null_type, boost::tuples::null_type,
   boost::tuples::null_type, boost::tuples::null_type,
   boost::tuples::null_type, boost::tuples::null_type,
   boost::tuples::null_type, boost::tuples::null_type> > >,
   boost::tuples::null_type, boost::tuples::null_type,
   boost::tuples::null_type, boost::tuples::null_type,
   boost::tuples::null_type, boost::tuples::null_type,
   boost::tuples::null_type, boost::tuples::null_type> >]((+__val))' to
`bool'
/usr/include/c++/3.3.3/bits/stl_algo.h:298: instantiated from
`_InputIter std::find(_InputIter, _InputIter, const _Tp&) [with
_InputIter = __gnu_cxx::__normal_iterator<Test*, std::vector<Test,
std::allocator<Test> > >, _Tp =
boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::relational_action<boost::lambda::equal_action>,
boost::tuples::tuple<const int,
boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<2,
boost::lambda::function_action<2, boost::lambda::detail::unspecified> >,
boost::tuples::tuple<int (Test::*const)() const, const
boost::lambda::lambda_functor<boost::lambda::placeholder<1> >,
boost::tuples::null_type, boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type> > >,
boost::tuples::null_type, boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type> > >]'
lambda2.cc:28: instantiated from here
/usr/include/c++/3.3.3/bits/stl_algo.h:211: error: could not convert `
   boost::lambda::operator==(const A&, const
   boost::lambda::lambda_functor<Arg>&) [with A = Test, Arg =

boost::lambda::lambda_functor_base<boost::lambda::relational_action<boost::lambda::equal_action>,
boost::tuples::tuple<const int,

Compilation exited abnormally with code 2 at Wed Jan 11 12:21:07

Next message: Nat Goodspeed: "Re: [Boost-users] Pyste/Pyplusplus/Boost documentation problems"
Previous message: Drumheller, Michael: "[Boost-users] Pyste/Pyplusplus/Boost documentation problems"
Next in thread: Peter Dimov: "Re: [Boost-users] [lambda] Operators"
Reply: Peter Dimov: "Re: [Boost-users] [lambda] Operators"
Reply: Daniel Wallin: "Re: [Boost-users] [lambda] Operators"
Reply: Jaakko Jarvi: "Re: [Boost-users] [lambda] Operators"

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