Re: [Boost-users] Simple Lambda Problem

7 Apr 2011

      On 04/07/2011 01:02 AM, Richard Howard wrote:
...
I am currently trying to get to grips with using Lambda, but I have
hit a problem fairly early on.
Can anyone explain what I am doing wrong.
bool isCar(std::string const&  val)
{
    return val.find("car") != std::string::npos;
}
int main()
{
    std::liststd::string  l;
    l.push_back("car");
    l.push_back("blue car");
    l.push_back("red van");
    l.push_back("bike");
    l.push_back("blue car");
// ...
l.remove_if(&isCar);
// this works and is how I have done things in the past but I was
hoping to avoid the need for the separate function by using Lambda.
    // I have tried the following
l.remove_if(boost::lambda::var(boost::lambda::bind(&std::string::find,
boost::lambda::_1, "car")) != std::string::npos);
// I am not sure why this does not work, can anyone point me in the
right direction?
}
Don't use var.  Also, I think std::string::find
is overloaded, so you'll need to cast it to
the correct member pointer type.

You can do better with phoenix which provides
find.  (Phoenix 2 is included under spirit,
Phoenix 3 will be released in 1.47.)  Actually,
with phoenix, you'll want to use search instead
of find, since find isn't specialized for string.

In Christ,
Steven Watanabe