问题描述
我想为Golang中的用法显示创建一个外部函数,但是我不知道如何调用flag变量.这是我的实际代码:
I want to create an external function for usage display in Golang, but I don't know how to call the flag variable. This is my actual code:
package main
import (
"flag"
"fmt"
"os"
)
func Usage() {
if ArgSend {
fmt.Printf("Usage: SEND")
flag.PrintDefaults()
os.Exit(0)
} else if ArgTest {
fmt.Printf("Usage: -test")
flag.PrintDefaults()
os.Exit(0)
} else if ArgMacro {
fmt.Printf("Usage: -macro")
os.Exit(0)
} else {
fmt.Printf("Usage of: <-test|-send|-macro>\n")
os.Exit(0)
}
}
func main() {
//defaults variables
ArgTest, ArgSend, ArgMacro := false, false, false
// Args parse
flag.BoolVar(&ArgTest, "-test", false, "run test mode")
flag.BoolVar(&ArgSend, "-send", false, "run send mode")
flag.BoolVar(&ArgMacro, "-macro", false, "run macro mode")
flag.Parse()
Usage()
}
返回此错误:
F:\dev\GoLang\gitlab\EasySend\tmp>go run stackoverflow.go -test
# command-line-arguments
.\stackoverflow.go:10:5: undefined: ArgSend
.\stackoverflow.go:15:12: undefined: ArgTest
.\stackoverflow.go:20:12: undefined: ArgMacro
如果ArgSend是true/false,如何检查标志解析?
How can I check flag parse if ArgSend is true/false?
推荐答案
您的示例中有几处错误:
A couple of things wrong in your example:
- 您尝试在使用函数中使用的变量不在范围内,因为所有标志变量都在main(.)内部声明.
-
标志变量本身的类型错误,应使用标志包中的类型 - 其他错误包括,在标记文本(第二个arg)
的前面添加-",并且不取消引用标记变量(它们将是指针)
这里有一个很好的例子: golang标志示例,您应检查标志上的godocs ,特别是对于默认行为和自定义用法,如果您在修改示例时遇到问题,请在此处再次询问
There is a good example here: golang flags example and you should check godocs on flags particularly for default behavior and custom usage functions, if you have trouble modifying the example then ask again here
已更新:抱歉,正如Peter在评论中指出的那样,我的回答有点混乱和错误.
Updated: Sorry, as Peter pointed to in comments my answer is a little muddled and incorrect.
为澄清起见,在给定flag.Bool的"golang标志示例"链接中提供的示例中.使用flag.Bool时,将返回一个指针.
To Clarify, in the example provided in the "golang flags example" link given flag.Bool is used. When using flag.Bool a pointer is returned.
在问题"中使用flag.BoolVar,它允许您引用布尔值.您在问题中使用flag.BoolVar实际上是正确的.
In the Question you use flag.BoolVar which allows you to reference a bool value. your use of flag.BoolVar in the question is in fact correct.
因此,您所需要做的就是解决范围界定问题,并不能真正弄清楚您打算如何使用用法",但这是一个工作示例,应予以澄清:
So all you need to do is address the scoping issue, not really clear what you are trying to do with your Usage but here is a working example that should clarify:
注意:在此示例中,标志vars可以留在main内部,因为在Usage函数中不需要它们
Note: in this example the flag vars could have stayed inside main as they are not required in the Usage function
package main
import (
"flag"
"fmt"
"os"
)
func Usage() {
// custom usage (help) output here if needed
fmt.Println("")
fmt.Println("Application Flags:")
flag.PrintDefaults()
fmt.Println("")
}
var ArgTest, ArgSend, ArgMacro bool
func main() {
// Args parse
flag.BoolVar(&ArgTest, "test", false, "run test mode")
flag.BoolVar(&ArgSend, "send", false, "run send mode")
flag.BoolVar(&ArgMacro, "macro", false, "run macro mode")
flag.Parse()
// assign custom usage function (will be shown by default if -h or --help flag is passed)
flag.Usage = Usage
// if no flags print usage (not default behaviour)
if len(os.Args) == 1 {
Usage()
}
fmt.Printf("ArgTest val: %t\n", ArgTest)
fmt.Printf("ArgSend val: %t\n", ArgSend)
fmt.Printf("ArgMacro val: %t\n", ArgMacro)
}
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