generic utils

generics.go

package main

import (
	"encoding/json"
	"fmt"
	"os"
)

func bar() (int, error) { return 2, fmt.Errorf("testerr") }

func main() {
	Must(bar())("bar")
}

func Must[T any](ret T, err error) func(s string) T {
	return func(s string) T {
		if err != nil {
			fmt.Printf("%s failed: %s", s, err)
			os.Exit(1)
		}
		return ret
	}
}

func DeepCopy[T any](de *T) *T {
	b, _ := json.Marshal(de)
	var ret T
	_ = json.Unmarshal(b, &ret)
	return &ret
}

// Opt returns the value pointed to by p, or the zero value of T if p is nil.
func Opt[T any](p *T) (res T) {
    if p != nil {
        res = *p
    }
    return
}

// Or returns the value of p if it is not nil, otherwise it returns the def.
func Or[T any](p *T, def T) T {
	if p != nil {
		return *p
	}
	return def
}

// Ternary returns a if condition is true, otherwise b.
// Note: Both arguments are evaluated before the function is called.
// PANIC: Ternary(len(slice) > 0, slice[0], "default")
func Ternary[T any](condition bool, a,b T) T {
	if condition {
		return a
	}
	return b
}

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