353solutions
Expose CSV options to Go
The arrow CSV package has the following options: ReadOptions, ParseOptions & ConvertOptions. Expose them to Go.
Problem
These option structs are C++ structs, they have a static Defaults function that
returns a struct (not pointer). When creating an arrow::csv::Reader you need
to pass options by reference.
cgo can’t work directly with C++, which means we can use them directly as
C.ParseOptions.
Possible Solutions
new function
A C function that will get all the parameters for an options struct and create it.
Problems
- Need to update the function every time options struct is updated at the C++ level
- Probably need to be part of making a reader since we need to pass the struct by reference
- A lot of parameters1, since we have several such options struct
Use Pointers
Have C wrappers that will create a pointer to options struct and have setters.
Problems
- Who frees the memory?
- A lot of setter functions
- Extra memory allocation
C Shadow struct
Have a C struct that will be a copy of the C++ struct. Can be used directly from Go and passed around by value.
Problems
- Need to be in par with C++
- Duplication (code & memory)
- Since it’s a creator function, don’t see memory as a bit problem
SWIG
Use swig to generate wrappers.
Problems
- Learning curve
- Looks like need to be more systematic approach
- Not sure how it’ll work with C++ calling into Go (GoStream class)
1: If you have a procedure with 10 parameters, you probably missed some. - Alan Perlis
This can be a good POC for SWIG, yet I don't think SWIG will be our silver bullet so It might not be worth to add complexity to our system with it. I think a functional API is a good choice, it gives you an ability to have a good default and to expose the parameters in a need to have way (easy to extend).
I'll probably go with C shadow struct for now. I'll defer SWIG for when we go all-in on it.