Match dynamic interfaces with dynamic type

[nightlyone]

I tried to write a matcher that matches

x == y and x != y

as well as the condition that for those variables exist a method name Equal with the signature (r T) Equal(other T) bool where the the type T should be dynamic.

The reason is that I want enforce the usage of this method and maybe even automatically fix this.

We have a lot of types where we need this. So doing one rule for each type is not really feasible.

[quasilyte]

Hello.

We can start by figuring out a potential syntax/methods to express that constraint.

How would you want to write such a pattern if that feature already existed?

[nightlyone]

@quasilyte I tried to express it like this

m.Match(`$x == $y`).
	Where(m["x"].Type.Implements(`interface { Equal($x.type)) bool}`)).
	Suggest(`$x.Equal($y)`)
m.Match(`$x != $y`).
	Where(m["x"].Type.Implements(`interface { Equal($x.type)) bool}`)).
	Suggest(`!$x.Equal($y)`)

I suggest the $arg.type syntax for this, since it is impossible to have such a method in Go code that parses.

Unfortunately the string argument to Implements does no interpolation of parameters at the moment.

[quasilyte]

Sorry for the delayed response.

What makes it complicated is that normal Go parser can't handle $ symbols. Only gogrep parser can do that. But suppose we can parse it.

The other difficulty is that $x.type that is not valid syntax for gogrep parser either. We could use something like typeof($x) to circumvent that.

I like the rule that you're trying to express, but it's hard to predict when this feature will be implemented. #16 currently has higher priority and I'm still trying to find the free time to resolve it. :)