loop -> for_each advanced

[ibe]

Hi,
i can't get the clue:
I have had a loop in my code like this:

---snip---

class Foo {
accept(Visitor& v) {
v.visit(*this);
}
};

class Visitor {
visit (Foo& f) {
...
}
}

....in main...

Visitor v(arugments, ...);
for (std::deque<Foo*>::iterator iter = list_.begin();
iter != m_list.end();
++iter) {
(*iter)->accept(v);
}

---snip---

by means of the boost::bind i could express the loop with

std::for_each(list_.begin(), list_.end(),
bind(mem_fun(&Foo::accept), _1, v));

fine!
But now things changed to something like

std::deque<boost::shared_ptr<Foo> > list_;

I dont have an idea how could i express the same loop under this
curcumstances.
Can anyone help me?

thx in advance
Bernhard

 

[Victor Bazarov]

i can't get the clue:
I have had a loop in my code like this:

---snip---

class Foo {
public:

accept(Visitor& v) {

void accept(Visitor& v) {

v.visit(*this);
}
};

class Visitor {
public:

visit (Foo& f) {
...
}
} ;

...in main...

Visitor v(arugments, ...);
for (std::deque<Foo*>::iterator iter = list_.begin();
iter != m_list.end();
++iter) {
(*iter)->accept(v);

That should work for your new solution as well...

}

---snip---

by means of the boost::bind i could express the loop with

std::for_each(list_.begin(), list_.end(),
bind(mem_fun(&Foo::accept), _1, v));

fine!
But now things changed to something like

std::deque<boost::shared_ptr<Foo> > list_;

I dont have an idea how could i express the same loop under this
curcumstances.
Can anyone help me?

Doesn't it still compile? If it doesn't what error message do you get?
Post the minimal complete compilable code that exhibits the problem you
are talking about.

V

 

[Jeff Flinn]

Hi,
i can't get the clue:
I have had a loop in my code like this:

---snip---

class Foo {
accept(Visitor& v) {
v.visit(*this);
}
};

class Visitor {
visit (Foo& f) {
...
}
}

...in main...

Visitor v(arugments, ...);
for (std::deque<Foo*>::iterator iter = list_.begin();
iter != m_list.end();
++iter) {
(*iter)->accept(v);
}

---snip---

by means of the boost::bind i could express the loop with

std::for_each(list_.begin(), list_.end(),
bind(mem_fun(&Foo::accept), _1, v));

fine!
But now things changed to something like

std::deque<boost::shared_ptr<Foo> > list_;

std::for_each
( list_.begin()
, list_.end()
, bind( &Foo::accept, _1, v )
);

should do it. Note that with the above, v is copied. Alternatively pass
boost::ref(v) to pass a reference to your v.

Jeff

 

[ibe]

public:

yes, of course.
[all other typos snipped]

That should work for your new solution as well...

yes it does, but i wanna get the..

....thing work

Doesn't it still compile? If it doesn't what error message do you get?
Post the minimal complete compilable code that exhibits the problem you
are talking about.

it can't bind any more, because the iteraters are now of type shared_ptr
and no raw pointers.

B

 

[ibe]

std::for_each
( list_.begin()
, list_.end()
, bind( &Foo::accept, _1, v )
);

you are absolutely right! std::mem_fun is too much.
Thanks a lot for the hint with boost::ref too!

B

 

[Luke Meyers]

it can't bind any more, because the iteraters are now of type shared_ptr
and no raw pointers.

Try boost::mem_fn instead of std::mem_fun. It handles smart pointers
transparently, IIRC.

Luke