[Boost-users] [Fwd: Re: [interprocess] shared_memory_object design]

Subject: [Boost-users] [Fwd: Re: [interprocess] shared_memory_object design]
From: Ion Gaztañaga (igaztanaga_at_[hidden])
Date: 2009-08-27 16:45:35

attached mail follows:

Christian Henning escribió:
> Hi there, a colleague of mine is questioning the design decisions in
> the shared_memory_object class. The assignment operator and copy
> constructor are private. Why?

Because the class own a unique resource just like a file. Is fstream 
copyable? No, movable (in c++0x) just like shared_memory_object. What 
should the copy constructor do?

Also the constructor takes a type
> instead of a value as the first parameter. In his eyes it makes it
> very inflexible since the creation of or attaching to shared_memory
> area has to known at compile time.

Ok, this is debatable, because with move semantics you can write:

shared_memory_object obj(create?
                        shared_memory_object(create_only, ...):
                         shared_memory_object(open_only, ...));

or

shared_memory_object shm;

if(create){
    shared_memory_object tmp(create_only);
    tmp.swap(shm);
}
else{
    shared_memory_object tmp(open_only);
    tmp.swap(shm);
}

Best,

Ion

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