// Copyright 2018 Frank Schroeder. All rights reserved.

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

package properties

import "flag"

// MustFlag sets flags that are skipped by dst.Parse when p contains

// the respective key for flag.Flag.Name.

//

// It's use is recommended with command line arguments as in:

// 	flag.Parse()

// 	p.MustFlag(flag.CommandLine)

func (p *Properties) MustFlag(dst *flag.FlagSet) {

	m := make(map[string]*flag.Flag)

	dst.VisitAll(func(f *flag.Flag) {

		m[f.Name] = f

	})

	dst.Visit(func(f *flag.Flag) {

		delete(m, f.Name) // overridden

	})

	for name, f := range m {

		v, ok := p.Get(name)

		if !ok {

			continue

		}

		if err := f.Value.Set(v); err != nil {

			ErrorHandler(err)

		}

	}

}