must.go

/*******************************************************************************
*
* Copyright 2022 SAP SE
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You should have received a copy of the License along with this
* program. If not, you may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*******************************************************************************/

// Package must contains convenience functions for quickly exiting on fatal
// errors without the need for excessive "if err != nil".
package must

import "github.com/sapcc/go-bits/logg"

// Succeed logs a fatal error and terminates the program if the given error is
// non-nil. For example, the following:
//
//	fileContents := []byte("loglevel = info")
//	err := os.WriteFile("config.ini", fileContents, 0666)
//	if err != nil {
//	  logg.Fatal(err.Error())
//	}
//
// can be shortened to:
//
//	fileContents := []byte("loglevel = info")
//	must.Succeed(os.WriteFile("config.ini", fileContents, 0666))
func Succeed(err error) {
	if err != nil {
		logg.Fatal(err.Error())
	}
}

// Return is like Succeed(), except that it propagates a result value on success.
// This can be chained with functions returning a pair of result value and error
// if errors are considered fatal. For example, the following:
//
//	buf, err := os.ReadFile("config.ini")
//	if err != nil {
//	  logg.Fatal(err.Error())
//	}
//
// can be shortened to:
//
//	buf := must.Return(os.ReadFile("config.ini"))
func Return[T any](val T, err error) T {
	Succeed(err)
	return val
}