Can we make the `fromJSON` function support string pointer?

[Cassius0924]

The current fromJSON function only supports parameters of type string. If I pass a parameter of type *string, it throws an error.

[antonmedv]

Looks like a deref is missing. Could you please share the whole example?

[Cassius0924]

Looks like a deref is missing. Could you please share the whole example?看起来缺少 deref。您能分享整个示例吗？

sure!

package main

import (
	"fmt"

	"github.com/expr-lang/expr"
)

func main() {
	jsonString := `{"Num": 1}`
	env := map[string]any{
		"aJSONString": &jsonString,
	}

	code := "fromJSON(aJSONString)"
	result, err := expr.Eval(code, env)
	if err != nil {
		panic(err)
	}
	fmt.Println(result)
}

panic: interface conversion: interface {} is *string, not string (1:1)
	 | fromJSON(aJSONString)
	 | ^

goroutine 1 [running]:

[Cassius0924]

and split

[antonmedv]

I fixed it! It took me quite a lot of programming, but I figure out the correct way to add support for *type for all builtins.

Compiler will add OpDeref only if it is needed. I also added a lot of tests for all builtins, so it should be fixed!