blocks|key|1289403|text|在这种情况下，缺少强制的--output选项，因此请在调用parse!之后执行此操作|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1289404|unless+files[:input]+&&+files[:output]
++$stderr.puts+"Error:+you+must+specify+both+--input+and+--output+options."
++exit+1
end|code-block|syntax|javascript|1289405|entityMap^0|C|8|T|6|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

In this case, the mandatory <code>--output</code> option is missing, so do this after calling <code>parse!</code>:

<pre><code>unless files[:input] &amp;&amp; files[:output]
 $stderr.puts "Error: you must specify both --input and --output options."
 exit 1
end
</code></pre>

blocks|key|1289498|text|OK+-这是可行的--+on()调用中的正则表达式允许任何字符串，只要它不以'-‘开头|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1289499|如果我没有向--input传递参数，而下游有另一个选项，那么它会将该选项键作为参数传递给--input。(例如--输入--输出)。regexp捕捉到这一点，然后我检查错误消息。如果它报告的参数以'-‘开头，我会输出正确的错误消息，即缺少参数。不是很漂亮，但似乎很管用。|1289500|以下是我的工作测试用例：|1289501|#!/usr/bin/env+ruby
require+'optparse'
files+=+Hash.new

option_parser+=+OptionParser.new+do+%7Copts%7C
++opts.on('-i+FILENAME',+'--input+FILENAME',+/\A[%5E\-]%2B/,+'Input+filename+-+required')+do+%7Cfilename%7C
++++files[:input]+=+filename
++end
++opts.on('-o+FILENAME',+'--output+FILENAME',+/\A[%5E\-]%2B/,+'Output+filename+-+required')+do+%7Cfilename%7C
++++files[:output]+=+filename
++end
end

begin
++option_parser.parse!(ARGV)
rescue+OptionParser::ParseError
++if+$!.to_s+=~+/invalid\s%2Bargument\:\s%2B(\-\-\S%2B)\s%2B\-/
++++$stderr.print+"Error:+missing+argument:+#{$1}\n"
++else+
++++$stderr.print+"Error:+"+%2B+$!+%2B+"\n"
++end++
++exit
end

files.keys.each+do+%7Ckey%7C
++print+"#{key}++#{files[key]}\n"
end|code-block|syntax|javascript|1289502|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|O|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|P|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

OK - this works - the regular expression in the on() call allows any string as long as it doesn't start with a '-'

If I don't pass an argument to --input and there is another option downstream then it will take that option key as the argument to --input. (e.g. --input --output). The regexp catches that and then I check the error message. If the argument it reports starts with '-' I output the correct error message, namely that there is a missing argument. Not pretty but it seems to work.

Here is my working test case:

<pre><code>#!/usr/bin/env ruby
require 'optparse'
files = Hash.new

option_parser = OptionParser.new do |opts|
 opts.on('-i FILENAME', '--input FILENAME', /\A[^\-]+/, 'Input filename - required') do |filename|
 files[:input] = filename
 end
 opts.on('-o FILENAME', '--output FILENAME', /\A[^\-]+/, 'Output filename - required') do |filename|
 files[:output] = filename
 end
end

begin
 option_parser.parse!(ARGV)
rescue OptionParser::ParseError
 if $!.to_s =~ /invalid\s+argument\:\s+(\-\-\S+)\s+\-/
 $stderr.print "Error: missing argument: #{$1}\n"
 else 
 $stderr.print "Error: " + $! + "\n"
 end 
 exit
end

files.keys.each do |key|
 print "#{key} #{files[key]}\n"
end
</code></pre>

blocks|key|1289631|text|你想做的不是一个好主意。如果你真的有一个名为"--output“的文件呢？这是Unix上完全有效的文件名。每个Unix程序的选项解析的工作方式与ruby一样，所以您不应该更改它，因为这样您的程序将与其他程序完全不同，这是令人困惑的，并且违反了“最小惊讶原则”。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1289632|真正的问题是:为什么你一开始就有这个问题？也许您正在从另一个程序运行您的程序，而父程序提供了一个空文件名作为--input的参数，这使它看到--output作为--input的参数。您可以通过始终引用您在命令行传递的文件名来解决此问题：|1289633|./test_case.rb+--input+""+--output+"bar"|code-block|syntax|javascript|1289634|然后--输入将为空，这很容易检测到。|1289635|还要注意，如果--input设置为--output+(并且--output不是一个真正的文件)，您可以只尝试打开--input文件。如果失败，则打印如下消息：|1289636|can't+open+input+file:+--output:+file+not+found|1289637|这应该让用户清楚他们做错了什么。|1289638|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|F|7|X|8|@]|9|@]|A|$G|H]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

What you want to do is not a good idea. What if you really have a file named "--output"? This is a perfectly valid filename on Unix. Every Unix program's option parsing works the way the ruby one is doing, so you shouldn't change it, because then your program will be arbitrarily different from everything else, which is confusing and violates the "principle of least surprise."

The real question is: why are you having this problem in the first place? Perhaps you're running your program from another program, and the parent program is providing a blank filename as the parameter to --input, which makes it see --output as the parameter to --input. You can work around this by always quoting the filenames you pass on the command line:

<pre><code>./test_case.rb --input "" --output "bar"
</code></pre>

Then --input will be blank, and that's easy to detect.

Also note that if --input is set to --output (and --output is not a real file) you can just try to open the --input file. If it fails, print a message like:

<pre><code>can't open input file: --output: file not found
</code></pre>

And that should make it clear to the user what they did wrong.

blocks|key|1074843|text|试试这个：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1074844|opts.on('-i',+'--input+FILENAME',+'Input+filename+-+required')+do+%7Cfilename%7C
++files[:input]+=+filename
end

opts.on('-o',+'--output+FILENAME',+'Output+filename+-+required')+do+%7Cfilename%7C
++files[:output]+=+filename
end

opts.on("-h",+"--help",+"Show+this+message")+do+
++puts+opts
++exit
end


begin
++ARGV+<<+"-h"+if+ARGV.size+!=+2+++
++option_parser.parse!(ARGV)
rescue+OptionParser::ParseError
++$stderr.print+"Error:+"+%2B+$!+%2B+"\n"
++exit
end|code-block|syntax|javascript|1074845|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

try this:

<pre><code>opts.on('-i', '--input FILENAME', 'Input filename - required') do |filename|
 files[:input] = filename
end

opts.on('-o', '--output FILENAME', 'Output filename - required') do |filename|
 files[:output] = filename
end

opts.on("-h", "--help", "Show this message") do 
 puts opts
 exit
end


begin
 ARGV &lt;&lt; "-h" if ARGV.size != 2 
 option_parser.parse!(ARGV)
rescue OptionParser::ParseError
 $stderr.print "Error: " + $! + "\n"
 exit
end
</code></pre>

In OptionParser I can make an option mandatory, but if I leave out that value it will take the name of any following option as the value, screwing up the rest of the command line parsing. 
Here is a test case that echoes the values of the options:

<pre><code>$ ./test_case.rb --input foo --output bar
output bar
input foo
</code></pre>

Now leave out the value for the first option:

<pre><code>$ ./test_case.rb --input --output bar
input --output
</code></pre>

Is there some way to prevent it taking another option name as a value?
Thanks!

Here is the test case code:

<pre><code>#!/usr/bin/env ruby
require 'optparse'
files = Hash.new

option_parser = OptionParser.new do |opts|
 opts.on('-i', '--input FILENAME', 'Input filename - required') do |filename|
 files[:input] = filename
 end
 opts.on('-o', '--output FILENAME', 'Output filename - required') do |filename|
 files[:output] = filename
 end
end

begin
 option_parser.parse!(ARGV)
rescue OptionParser::ParseError
 $stderr.print "Error: " + $! + "\n"
 exit
end

files.keys.each do |key|
 print "#{key} #{files[key]}\n"
end
</code></pre>

How do I handle a missing mandatory argument in Ruby OptionParser?

Unix

在OptionParser中，我可以强制设置一个选项，但是如果我省略了这个值，它将接受后面任何选项的名称作为值，这会搞乱命令行解析的其余部分。下面是一个测试用例，它反映了选项的值：$ ./test_case.rb --input foo --output baroutput  barinput  foo现在省略第一个选...

问如何处理Ruby OptionParser中缺少的强制参数？
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