cfcbb4227f
This does not yet include support for the //go:embed directive added in this release. * Makefile.am (check-runtime): Don't create check-runtime-dir. (mostlyclean-local): Don't remove check-runtime-dir. (check-go-tool, check-vet): Copy in go.mod and modules.txt. (check-cgo-test, check-carchive-test): Add go.mod file. * Makefile.in: Regenerate. Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/280172
42 lines
988 B
Go
42 lines
988 B
Go
// Copyright 2020 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package flag_test
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import (
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"errors"
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"flag"
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"fmt"
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"net"
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"os"
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)
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func ExampleFunc() {
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fs := flag.NewFlagSet("ExampleFunc", flag.ContinueOnError)
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fs.SetOutput(os.Stdout)
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var ip net.IP
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fs.Func("ip", "`IP address` to parse", func(s string) error {
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ip = net.ParseIP(s)
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if ip == nil {
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return errors.New("could not parse IP")
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}
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return nil
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})
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fs.Parse([]string{"-ip", "127.0.0.1"})
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fmt.Printf("{ip: %v, loopback: %t}\n\n", ip, ip.IsLoopback())
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// 256 is not a valid IPv4 component
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fs.Parse([]string{"-ip", "256.0.0.1"})
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fmt.Printf("{ip: %v, loopback: %t}\n\n", ip, ip.IsLoopback())
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// Output:
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// {ip: 127.0.0.1, loopback: true}
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//
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// invalid value "256.0.0.1" for flag -ip: could not parse IP
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// Usage of ExampleFunc:
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// -ip IP address
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// IP address to parse
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// {ip: <nil>, loopback: false}
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}
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