如何加强与NDesk.Options所需的命令行选项？ [英] How to enforce required command-line options with NDesk.Options?

问题描述

我只是写一个控制台程序，并决定使用命令行解析NDesk.Options。我的问题是，我该如何执行所需的命令行选项？

我在文档是：

  

用所需的值选项（追加'='的选项名称）或可选的值（追加'：'给选项名称）。

然而，当我把 = 在选项名称的末尾有行为没有区别。理想情况下，Parse方法会抛出异常。

有没有别的东西，我需要做什么？

下面是我的测试code：

 类节目
{
    静态无效的主要（字串[] args）
    {
        布尔show_help = FALSE;
        字符串someoption = NULL;        VAR P =新OptionSet（）{
            {someoption =，一些字符串选项，V = GT; someoption = V}，
            {H |帮助，显示此消息并退出，V = GT; show_help = V！= NULL}
        };        清单＆LT;串GT;额外;
        尝试
        {
            额外= p.Parse（参数）;
        }
        赶上（OptionException E）
        {
            System.Console.Write（myconsole：）;
            的System.Console.WriteLine（e.Message）;
            的System.Console.WriteLine（尝试'myconsole --help以获取更多信息。）;
            返回;
        }        如果（show_help）
        {
            ShowHelp（P）;
            返回;
        }        的System.Console.WriteLine（==================）;
        的System.Console.WriteLine（someoption）;
    }    静态无效ShowHelp（OptionSet P）
    {
        的System.Console.WriteLine（用法：myconsole [OPTIONS]）;
        的System.Console.WriteLine（）;
        的System.Console.WriteLine（选项：）;
        p.WriteOptionDescriptions（System.Console.Out）;
    }
}
 

解决方案

的问题是，文件不明确的，因为它显然需要是。 ： - （

具体地讲，每

<一个href=\"http://www.ndesk.org/doc/ndesk-options/NDesk.Options/OptionValueType.html#F:NDesk.Options.OptionValueType.Required\">http://www.ndesk.org/doc/ndesk-options/NDesk.Options/OptionValueType.html#F:NDesk.Options.OptionValueType.Required

的 = 中的一个选项规范并不适用于OptionSet作为一个整体，只是给的值的该特定选项。

这一点的重要性实际上只有在两种情况下相关的，所以首先让我们考虑OptionSet解析器：

 字符串= NULL;
字符串B = NULL;
VAR的选择=新OptionSet {
    {一个=，V =＆GT; A = V}，
    {B =，V =＆GT; B = V}，
};
 

方案1在那里重要的是，OptionSet.Parse（）工作在单通，只进的方式，并执行的不的看选项值，以确定他们是否应该是值。因此，考虑：

  options.Parse（新[] { - 一个，-b}）;
 

这样做的结果将是 A 值为 - B和 b 是空。由于处理程序 -a 的需要的值，它的总是的获取以下值（除非该值是EN codeD到原来的选项，如： -a =值）。

第二个地方，这是很重要的是当值需要选择是最后的选择，并没有为它的价值present：

  options.Parse（新[] { - 一个}）;
 

这将引发OptionException，因为处理程序 -a 的需要的一个值，没有值是present。

因此​​，如果你有自己需要（而不是需要值的选项）选项，则需要手动检查这一点：

 字符串DIR = NULL;
新OptionSet {
    {O =，V = GT; DIR = V}，
} .Parse（参数）;如果（DIR == NULL）
    抛出新的InvalidOperationException异常（缺少必需的选项-o = DIR）;
 

I was just writing a console utility and decided to use NDesk.Options for command-line parsing. My question is, How do I enforce required command-line options?

I see in the docs that:

options with a required value (append '=' to the option name) or an optional value (append ':' to the option name).

However, when I put a = at the end of the option name there is no difference in behavior. Ideally the Parse method would throw an exception.

Is there something else I need to do?

Here is my test code:

class Program
{
    static void Main(string[] args)
    {
        bool show_help = false;
        string someoption = null;

        var p = new OptionSet() {
            { "someoption=", "Some String Option", v => someoption = v},
            { "h|help",  "show this message and exit", v => show_help = v != null }
        };

        List<string> extra;
        try
        {
            extra = p.Parse(args);
        }
        catch (OptionException e)
        {
            System.Console.Write("myconsole: ");
            System.Console.WriteLine(e.Message);
            System.Console.WriteLine("Try `myconsole --help' for more information.");
            return;
        }

        if (show_help)
        {
            ShowHelp(p);
            return;
        }

        System.Console.WriteLine("==================");
        System.Console.WriteLine(someoption);
    }

    static void ShowHelp(OptionSet p)
    {
        System.Console.WriteLine("Usage: myconsole [OPTIONS]");
        System.Console.WriteLine();
        System.Console.WriteLine("Options:");
        p.WriteOptionDescriptions(System.Console.Out);
    }
}

解决方案

The problem is that documentation isn't as clear as it apparently needs to be. :-(

Specifically, as per:

http://www.ndesk.org/doc/ndesk-options/NDesk.Options/OptionValueType.html#F:NDesk.Options.OptionValueType.Required

The = within an option specification doesn't apply to the OptionSet as a whole, but just to the value for that specific option.

The importance of this is really only relevant in two scenarios, so first let's consider the OptionSet parser:

string a = null;
string b = null;
var options = new OptionSet {
    { "a=", v => a = v },
    { "b=", v => b = v },
};

Scenario 1 where it's important is that OptionSet.Parse() works in a single-pass, forward-only manner, and does not look at option values to determine if they "should be" values. Thus, consider:

options.Parse(new[]{"-a", "-b"});

The result of this will be that a has the value "-b", and b is null. Since the handler for -a requires a value, it always gets the following value (unless the value is "encoded" into the original option, e.g. -a=value).

The second place where this is important is when a value-requiring option is the last option, and there isn't a value present for it:

options.Parse(new[]{"-a"});

This will throw an OptionException, as the handler for -a requires a value, and no value is present.

Consequently, if you have an option that itself is required (as opposed to an option that requires a value), you need to manually check for this:

string dir = null;
new OptionSet {
    { "o=", v => dir = v },
}.Parse (args);

if (dir == null)
    throw new InvalidOperationException ("Missing required option -o=DIR");

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