Re: Converting static libs to DLLs

"Ben Voigt [C++ MVP]" <rbv@newsgroups.nospam>
Mon, 20 Jul 2009 16:08:24 -0500
"Alex Blekhman" <> wrote in message

"Ben Burnett" wrote:

Has anyone converted a large number of static libraries to DLLs using an
automated method (or semi-automated)?

I'm not sure it is possible to do it automatically unless you have highly
sofisticated parser tool which can patch the files according to predefined
rules. In order to make a DLL from LIB you need to do the following steps:

1. Go through all headers and add calling convention and
__declspec(dllimport/dllexport) modifiers for each function declaration.
You can spare __declspec(dllimport/dllexport) if you strive for cross
platform code, however you will need to add .DEF file to the project with
all exported names. Alternatively, you can define a macro that will expand
to __declspec(dllimport) for client builds, to __declspec(dllexport) for
the DLL build and to nothing for Unix builds.

2. Change the project type to DLL instead of LIB. I think the easiest way
is to create new DLL project with VC++ and add to it existing source

Or you could not touch the source code at all (you don't even need to have
it) and create a linker .def file with a list of symbols in the EXPORTS
section. The lib and dumpbin tools may help you get a list of all symbols
in the .lib file.

This was the easy part. Then you will need to think out the types
transferred between DLL and its callers. If these types require
allocation/freeing memory, then both DLL and its client must use DLL
version of CRT in order to preserve memory heap integrity. The other way
is to export additional functions that will within DLL free whatever was
allocated there. Or you can fall back to fundamental C types in the same
way as Win32 API does, for example.

These are still valid points though, the DLL will not find the caller's
version of the C runtime functions the way a static lib does.


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