I'm working in a C workspace in VS2017, having two projects in the workspace: a utility project and a main project that uses the utility project.

After I added a new class (".h" and ".cpp" files) to the utility project, I noticed that although I make changes in the code, the ".lib" file is not rewritten when I build it, unless I change a method whose declaration includes __declspec(dllexport). It appears that I have to add this declaration, since otherwise, a derived issue is that of course the main project has linkage errors.

Is there a more elegant way to do it rather than adding __declspec(dllexport) before the declaration of every public method, like in the code below?

public:
    __declspec(dllexport) MyProperty(const std::string &csvLine);
    __declspec(dllexport) bool getIsActive();
    __declspec(dllexport) std::string getFormatting();
    __declspec(dllexport) PropertyType getType();

CodePudding user response：

You can add the declaration to the class, instead of to the individual methods:

class __declspec(dllexport) MyProperty
{
public:
    MyProperty(const std::string &csvLine);
    bool getIsActive();
    std::string getFormatting();
    PropertyType getType();
};

Note that for the class, the place is slightly different for methods - not in front of the complete declaration, but between the class keyword the class name.

As a followup, often a macro is used instead, which is defined to be either __declspec(dllexport) or __declspec(dllimport), depending on some preprocessor condition specifying whether we are currently compiling the dll or trying to use it:

#if defined(MY_DLL)
    #define MY_DLL_API __declspec(dllexport)
#else
    #define MY_DLL_API __declspec(dllimport)
#endif

class MY_DLL_API MyProperty
{
public:
    MyProperty(const std::string &csvLine);
    bool getIsActive();
    std::string getFormatting();
    PropertyType getType();
};

For your dll project, you then define MY_DLL, and for everyone who just uses the dll (without having MY_DLL defined), the header will automatically have the required dllimport.