Chaining Pack() Custom, with struc.Pack()

[abourget]

Since struc.Pack() doesn't return the number of written bytes, it's not easy to implement the Pack(...) (int, error) Custom method, that requires the number of written bytes, when that implementation calls struc.Pack() to pack some subelements of a struct.

Is there a better way ?

My initial issue is I have a struct like:

type BaseVariant struct {
    Type Varuint16
    Impl interface{}
}

and I'd like Impl to sort of rescan if the interface{} is a struct, or an interface that would implement the Packer or Custom interfaces, but when I pack that struct, I get an error.

If that can be solved, then I don't need a custom packer that triggered my issue above!

[lunixbochs]

You should be able to call struc.Sizeof() to get the size that will be written.

[abourget]

yeah.. I would have liked to avoid that, for performance reasons.. since it will actually need to do a full packing in order to gauge its size, so it would run the algos twice.. that's the only way?

[abourget]

Would it be complex to have struc handle an interface{} in a field, as if it were calling struc.Pack() on it automatically?

Would you be open to such a contribution?

[abourget]

thanks!