does STL has a binder or an adaptor for type-casting?

[Diego Martins]

Let's say I have a vector of pointers of Base
vector<Base *> vec;

Now, someone assured me all elements of the vector are of dynamic type
Derived *.

I want to use for_each or other STL algorithms in this container using
Derived members.

My current workaround is presented as follows:

void KludgeFunction(Base * elem) {
static_cast<Derived *>(elem)->myDerivedOperation();
}
....
for_each(vec.begin(),vec.end(),KludgeFunction);


We know if vec was vector<Derived *>, we can do it more simply by:

for_each(vec.begin(),vec.end(),mem_fun(&Derived::myDerivedOperation));


Do you how can I build something to avoid writing the KludgeFunction?
- an interator adaptor?
- a binder?

any ideas?

Diego Martins
HP

 

[Victor Bazarov]

Let's say I have a vector of pointers of Base
vector<Base *> vec;

Now, someone assured me all elements of the vector are of dynamic type
Derived *.

I want to use for_each or other STL algorithms in this container using
Derived members.

My current workaround is presented as follows:

void KludgeFunction(Base * elem) {
static_cast<Derived *>(elem)->myDerivedOperation();
}
...
for_each(vec.begin(),vec.end(),KludgeFunction);


We know if vec was vector<Derived *>, we can do it more simply by:

for_each(vec.begin(),vec.end(),mem_fun(&Derived::myDerivedOperation));


Do you how can I build something to avoid writing the KludgeFunction?
- an interator adaptor?

What's an "interator"? Do you mean "iterator"?

- a binder?

any ideas?

What you described should be implemented using _polymorphic_ abilities
of the classes. Then there would be no need for "kludges" or "adapters".

V

 

[Daniel T.]

Let's say I have a vector of pointers of Base
vector<Base *> vec;

Now, someone assured me all elements of the vector are of dynamic type
Derived *.

I want to use for_each or other STL algorithms in this container using
Derived members.

My current workaround is presented as follows:

void KludgeFunction(Base * elem) {
static_cast<Derived *>(elem)->myDerivedOperation();
}
...
for_each(vec.begin(),vec.end(),KludgeFunction);


We know if vec was vector<Derived *>, we can do it more simply by:

for_each(vec.begin(),vec.end(),mem_fun(&Derived::myDerivedOperation));


Do you how can I build something to avoid writing the KludgeFunction?
- an interator adaptor?
- a binder?

any ideas?

The simplest fix would be to change your vector to 'vector<Derived*>'

 

[Pete Becker]

What's an "interator"? Do you mean "iterator"?

Of course. That's a very common typo.