1// Copyright 2018 Frank Schroeder. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package properties
6
7import "flag"
8
9// MustFlag sets flags that are skipped by dst.Parse when p contains
10// the respective key for flag.Flag.Name.
11//
12// It's use is recommended with command line arguments as in:
13// 	flag.Parse()
14// 	p.MustFlag(flag.CommandLine)
15func (p *Properties) MustFlag(dst *flag.FlagSet) {
16	m := make(map[string]*flag.Flag)
17	dst.VisitAll(func(f *flag.Flag) {
18		m[f.Name] = f
19	})
20	dst.Visit(func(f *flag.Flag) {
21		delete(m, f.Name) // overridden
22	})
23
24	for name, f := range m {
25		v, ok := p.Get(name)
26		if !ok {
27			continue
28		}
29
30		if err := f.Value.Set(v); err != nil {
31			ErrorHandler(err)
32		}
33	}
34}
35