Multi types

[rouzier]

Allow 26 different type aliases to be used.

This support the old positional alias syntax

./gengen -o ./btree github.com/joeshaw/gengen/examples/btree string string

Mix of named aliases and positional alias

./gengen -o ./btree github.com/joeshaw/gengen/examples/btree U=string string
./gengen -o ./btree github.com/joeshaw/gengen/examples/btree string U=string

Just aliases

./gengen -o ./btree github.com/joeshaw/gengen/examples/btree T=string U=string

[joeshaw]

Nice! This is great, thanks for the patch.

I think one nice enhancement might be to not require that the type being replaced be in the generic package, so that a user could use whatever type they wanted. It'd remove the compile-time dependency on gengen and potentially allow people to use richer interfaces than use interface{} as the base generic type. It'd also have the benefit of not needing to define types generic.{A-S,W-Z}. What do you think?

[rouzier]

That is a good idea.

Are you thinking something like this?

Before

type T string
type U interface{}

type Map interface {
  Insert(T, U) bool
  Delete(T) bool
}

./gengen -o ./map github.com/rouzier/map/map T=string U=int
or
./gengen -o ./map github.com/rouzier/map/map string int

After

type Map interface {
  Insert(string, int) bool
  Delete(string) bool
}

[joeshaw]

Yeah, although it'd be nice to still reference other packages. So that you could still do ./gengen -o ./map github.com/rouzier/map/map generic.T=string generic.U=int but maybe that's not that important.

I think the "naked" case does need to reference the generic.T etc. types for backward compatibility, though.