Difference between Data_Wrap_Struct and TypedData_Wrap_Struct?

Question

I'm wrapping a C struct in a Ruby C extension but I can't find the differente between Data_Wrap_Struct and TypedData_Wrap_Struct in the docs, what's the difference between the two functions?

Answer 1

It's described pretty well in the official documentation.

The tl;dr is that Data_Wrap_Struct is deprecated and just lets you set the class and the mark/free functions for the wrapped data. TypedData_Wrap_Struct instead lets you set the class and then takes a pointer to a rb_data_type_struct structure that allows for more advanced options to be set for the wrapping:

• the mark/free functions as before, but also
• an internal label to identify the wrapped type
• a function for calculating memory consumption
• arbitrary data (basically letting you wrap data at a class level)
• additional flags for garbage collection optimization

Check my unofficial documentation for a couple examples of how this is used.