[Boost-users] [BLL] Right usage of he placeholder _1 ?

From: pheres (pheres_at_[hidden])
Date: 2007-04-25 18:27:11

Hello,

I've two problems so far with a simple for_each:

1.

vector<string*> v2(10);
fill(v2.begin(), v2.end(), new string("hehe"));
for_each(v2.begin(), v2.end(), cout << *_1 << " "); // works
for_each(v2.begin(), v2.end(), delete _1 ); // error
// error: type ‘const struct
// boost::lambda::lambda_functor<boost::lambda::placeholder<1>     
// >’ argument given to ‘delete’, expected pointer

Shouldn't the placeholder _1 actually become a (string-)pointer as it 
obviously does in the expression above ( cout << *_1 << " " )?

2.

Is it possible to call member functions from an placeholder of a boost-like 
lambda expression?

vector<string> v3(10);
fill(v3.begin(), v3.end(), "hoho");
for_each(v3.begin(), v3.end(), cout << _1->c_str() << " "); // error
// error: base operand of ‘->’ has non-pointer type ‘const   
// boost::lambda::lambda_functor<boost::lambda::placeholder<1> >’

Thank you for any input!