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91daaabd56
The TextVar function makes it easier to integrate the flag package
with any Go type that implements encoding.Text{Marshaler,Unmarshaler}.
Fixes #45754
Change-Id: Id23c37d59cf8c9699a7943a22ce27a45eb685c0f
Reviewed-on: https://go-review.googlesource.com/c/go/+/313329
Trust: Joseph Tsai <joetsai@digital-static.net>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Joseph Tsai <joetsai@digital-static.net>
TryBot-Result: Gopher Robot <gobot@golang.org>
36 lines
847 B
Go
36 lines
847 B
Go
// Copyright 2022 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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"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 ExampleTextVar() {
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fs := flag.NewFlagSet("ExampleTextVar", flag.ContinueOnError)
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fs.SetOutput(os.Stdout)
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var ip net.IP
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fs.TextVar(&ip, "ip", net.IPv4(192, 168, 0, 100), "`IP address` to parse")
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fs.Parse([]string{"-ip", "127.0.0.1"})
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fmt.Printf("{ip: %v}\n\n", ip)
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// 256 is not a valid IPv4 component
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ip = nil
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fs.Parse([]string{"-ip", "256.0.0.1"})
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fmt.Printf("{ip: %v}\n\n", ip)
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// Output:
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// {ip: 127.0.0.1}
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//
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// invalid value "256.0.0.1" for flag -ip: invalid IP address: 256.0.0.1
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// Usage of ExampleTextVar:
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// -ip IP address
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// IP address to parse (default 192.168.0.100)
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// {ip: <nil>}
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}
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