Is there a Go equivalent to JavaScript's eval() function for dynamic code evaluation?

Evaluated/Executing Golang Code/Expression Like JavaScript's eval()

JavaScript's eval() method allows for the evaluation and execution of code/expressions dynamically. This raises the question of whether a similar functionality exists in Go.

Solution

Yes, it is possible to evaluate and execute Go code/expressions, particularly expressions, using the eval.go package from the Go standard library.

To achieve this, the following workflow is required:

1. Create a Package: This represents the code context in which the expressions will be evaluated.
2. Create a Scope: This represents the variable scope within the package.
3. Insert Constants: Insert the variables used in the expressions as constants into the package's scope.
4. Evaluate Expressions: Use the Eval function from the eval.go package to evaluate the expressions.

Example

Consider the JavaScript code provided:

var x = 10;
var y = 20;
var a = eval("x * y") + "<br>";
var b = eval("2 + 2") + "<br>";
var c = eval("x + 17") + "<br>";

var res = a + b + c;

The following Go code demonstrates how to evaluate these expressions:

import (
    "fmt"
    "go/types"
)

func main() {
    // Create a package
    pkg := types.NewPackage("main", "go.example.org/eval")

    // Create a scope
    scope := types.NewScope(pkg, types.Universe)

    // Insert constants
    scope.Insert(types.NewConst(types.NewVar(scope, "x", types.Int), types.Typ[types.Int], 10))
    scope.Insert(types.NewConst(types.NewVar(scope, "y", types.Int), types.Typ[types.Int], 20))

    // Evaluate expressions
    res := evalExpression(scope, pkg)
    fmt.Println(res) // 200\n4\n27
}

func evalExpression(scope *types.Scope, pkg *types.Package) string {
    expr, _ := types.ParseExpr("x * y + \"\n\"")
    result, _ := eval.Eval(expr, pkg, scope)
    return result.String()
}

The above is the detailed content of Is there a Go equivalent to JavaScript's eval() function for dynamic code evaluation?. For more information, please follow other related articles on the PHP Chinese website!