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This is a follow up question to: Using export keyword with templates
As mentioned in the answers of the original questions 'export' is deprecated in C++0x and rarely supported by compilers even for C++03. Given this situation, in what way can one hide actual implementations in lib files and just expose declarations through header files, So that end user can know what are the signatures of the exposed API but not have access to the source code implementing the same?
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Separating interface from implementation allows to fully use polymorphism. In this way SomeComponentV2Impl will have 3 types - own, base class, and interface. Here you may just use only the interface without caring about it's implementation in further classes.
In the C language, a good way to separate interface from implementation is to put the interface in a `header file' with suffix . h , and the implementation in a file with suffix . c . Clients get access to the interface by including the header file.
So separating interfaces from implementations and using polymorphism makes for code that's simpler to read and understand, and that's less likely to have bugs. This is one of the strongest features of OOP.
C++ allows developers to separate the implementation code for member functions from the class definition, but there is no comparable support for separating the member data that implements an object's state (or, for that matter, for separating the declarations of private member functions).
In practice you cannot.
Only if you have a certain set of specializations, you can put these in a library. The base template cannot be put there.
On the other hand, using export did not hide the source. The compiler still needed it to instantiate new classes from the template.
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In short, you can't. The export keyword was a failed attempt to achieve something akin to non-source template libraries (though not even approaching the level of obfuscation that binary code achieves), and there is no replacement in the offing.
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