Renaming functions during compile

[vivshankar]

We have been using cel-go for many years and introduced a set of utilities that used cel.Function and cel.Overload, instead of receiver-style custom types. These functions required context from the activation and, since the function/overload does not have access to the activation, we ended up creating a new instance of the library for each call to execute the expression.

Example code:

// SomeLib constructs a library
func SomeLib(activation cel.Activation) cel.EnvOption {
	return cel.Lib(
		someLib{
			ctx: activation,
		})
}

type someLib struct {
	ctx cel.Activation
}

func (c someLib) CompileOptions() []cel.EnvOption {

	return []cel.EnvOption{

		cel.Function(

			"someFunc",

			cel.Overload("someFuncWithFilter", []*cel.Type{cel.StringType}, cel.DynType,

				cel.UnaryBinding(func(filter ref.Val) ref.Val {
                                         // extract some context from the activation using c.ctx
                                         // perform the function and return value
				}),
			),
                 ),
	}
}

We then extend the environment with a new instance of someLib per invocation. Given each extend results in copying objects, this has an impact overall on memory utilization. Unfortunately, since this has been in use for many years, replacing someFunc with something like some.func as a custom type receiver is challenging.

Is there any way that we might be able to do this during compile time when the AST is built?