Hello, did anyone knows where is the definition of the forward declaration class std_string in tkOStreamWrapper.h. Then I can include this file to make the std_string complete. I have searched all the head files, didn’t fined any content relate to std_string. There is a file vtkStdString.h, but it’s not the std_string.
As you can see, std_string is only used by reference, and it needs no definition. It’s just used with a bit of template magic to allow operator<< to work with std::string, without requiring vtkOStreamWrapper.h to do #include <string>.
The code has been this way (intentionally) for many years.