Re: Static methods and members

From:
"Victor Bazarov" <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++
Date:
Wed, 17 May 2006 15:56:35 -0400
Message-ID:
<e4fv5j$892$1@news.datemas.de>
Don't top-post, please. I've rearranged your reply.

Vincent RICHOMME wrote:

Victor Bazarov a 9crit :

Vincent RICHOMME wrote:

First my questions are related to C++ even if I am talking about
managed c++(.NET)...

I am currently implementing some interesting .NET classes in
c++(native code) and I am not an expert with static methods.
Here is what I am doing (class to manage processes) :

.h

namespace System{
namespace Diagnostics{

class ProcessStartInfo
{
[...]
};

class Process
{
[...]
static ProcessStartInfo m_ProcessStartInfo;
};

} //Diagnostics
} //System

//-------------------------------------------------------------------
.cpp
#include "SystemDiagnosticsProcess.h"
#include "Tlhelp32.h"

namespace System{
namespace Diagnostics{
[...]


Add here:

   ProcessStartInfo Process::m_ProcessStartInfo;

That's called "the definition" for your static data member.

} // Diagnostics
} // System

//-----------------------------------------------------------------

When I compile I get :
unresolved external symbol "protected: static class
System::Diagnostics::ProcessStartInfo
System::Diagnostics::Process::m_ProcessStartInfo"
(?m_ProcessStartInfo@Process@Diagnostics@System@@1VProcessStartInfo@23@A

How should I fix this.


See above.

Another question is, in managed c++ you can do :

 [...]


Ask in a newsgroup that deals with mananged C++. I only know of
'microsoft.public.vc.language', there are probably others.

V

Thanks for the answer about the definition but I have another
question : how con I declare a templated class called Array and
taking pointer on object.


template< arguments > class Array; // that's a declaration. Make sure
                                   // the arguments are the ones you want

I repeat just as an example in managed c++ (I don't want to go on a
newsgroup for .NET) you do this
array<Process^>^localAll = Process::GetProcesses();


I have no idea what it means.

How should I translate this into standard C++


How should I know? It's quite possible that it can't be translated.

Could the follwing work :

vector<Process*> processes = Process::GetProcesses();

and inside my Process::GetProcesses() I would do something like :

vector<Process*> Process::GetProcesses()
{
   BOOL bOk = FALSE;
   vector<Process*> processes;

   while(bOk)
   {
bOk = GetNexProcess(&sProcessInfoFromOS);
   processes.push_back( new Process( sProcessInfoFromOS ) );
   }

   return processes;
}


I don't know. Does it do what you want? What is it you want, actually?
You create a vector of pointers to 'Process' objects, and return it from
that function. Seems OK to me.

How can I rename vector<Process*> into Array<Process*>? Maybe I should
inheritate from vector but don't know how to do this, I could try this

template <typename Ptr>
class Array : public vector<Ptr>
{
};


Does it work for you? I often find the need to use non-default vector
constructors, so an empty class simply deriving from 'vector' won't
work because constructors are not inherited.

And I would like that when my array is destroyed all my pointers get
deallocated.


You would need to do it yourself. And I would recommend explicitly
naming your class to hint that it's an array of pointers:

    template<typename T> class AutoPtrArray : vector<T*>
    {
    public:
        ~AutoPtrArray() {
            for (size_t i = 0; i < size(); ++i)
                delete at(i);
        }
    };

V
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