我正在编写一个脚本，我想要一个带{value}的--host开关，但是如果没有指定--host开关，我希望选项解析失败。
我似乎无法弄明白该怎么做。文档似乎只指定了如何使参数值成为必需值，而不是交换机本身。
答案 0 :(得分：92)
使用optparse的方法，在丢失的开关上提供友好的输出：
#!/usr/bin/env ruby
require 'optparse'
options = {}
optparse = OptionParser.new do |opts|
opts.on('-f', '--from SENDER', 'username of sender') do |sender|
options[:from] = sender
end
opts.on('-t', '--to RECIPIENTS', 'comma separated list of recipients') do |recipients|
options[:to] = recipients
end
options[:number_of_files] = 1
opts.on('-n', '--num_files NUMBER', Integer, "number of files to send (default #{options[:number_of_files]})") do |number_of_files|
options[:number_of_files] = number_of_files
end
opts.on('-h', '--help', 'Display this screen') do
puts opts
exit
end
end
begin
optparse.parse!
mandatory = [:from, :to] # Enforce the presence of
missing = mandatory.select{ |param| options[param].nil? } # the -t and -f switches
unless missing.empty? #
raise OptionParser::MissingArgument.new(missing.join(', ')) #
end #
rescue OptionParser::InvalidOption, OptionParser::MissingArgument #
puts $!.to_s # Friendly output when parsing fails
puts optparse #
exit #
end #
puts "Performing task with options: #{options.inspect}"
在没有-t或-f开关的情况下运行会显示以下输出：
Missing options: from, to
Usage: test_script [options]
-f, --from SENDER username of sender
-t, --to RECIPIENTS comma separated list of recipients
-n, --num_files NUMBER number of files to send (default 1)
-h, --help
在begin / rescue子句中运行parse方法允许在其他失败时进行友好格式化，例如缺少参数或无效的开关值，例如，尝试为-n开关传递字符串。
答案 1 :(得分：59)
我假设您在这里使用optparse，尽管相同的技术可用于其他选项解析库。
最简单的方法可能是使用您选择的选项解析库解析参数，然后在host的值为nil时引发OptionParser :: MissingArgument异常。
以下代码说明了
#!/usr/bin/env ruby
require 'optparse'
options = {}
optparse = OptionParser.new do |opts|
opts.on('-h', '--host HOSTNAME', "Mandatory Host Name") do |f|
options[:host] = f
end
end
optparse.parse!
#Now raise an exception if we have not found a host option
raise OptionParser::MissingArgument if options[:host].nil?
puts "Host = #{options[:host]}"
使用
命令行运行此示例./program -h somehost
简单显示“Host = somehost”
虽然缺少-h且没有文件名运行会产生以下输出
./program:15: missing argument: (OptionParser::MissingArgument)
使用./program -h命令行运行
/usr/lib/ruby/1.8/optparse.rb:451:in `parse': missing argument: -h (OptionParser::MissingArgument)
from /usr/lib/ruby/1.8/optparse.rb:1288:in `parse_in_order'
from /usr/lib/ruby/1.8/optparse.rb:1247:in `catch'
from /usr/lib/ruby/1.8/optparse.rb:1247:in `parse_in_order'
from /usr/lib/ruby/1.8/optparse.rb:1241:in `order!'
from /usr/lib/ruby/1.8/optparse.rb:1332:in `permute!'
from /usr/lib/ruby/1.8/optparse.rb:1353:in `parse!'
from ./program:13
答案 2 :(得分：10)
我把它变成了一个可以从rubygems.org下载并安装的宝石：
gem install pickled_optparse
您可以在github上查看更新的项目源代码：
http://github.com/PicklePumpers/pickled_optparse
- 较早的帖子信息 -
这真的，真的让我烦恼所以我修好了并保持使用超级DRY。
要进行切换，只需在选项数组中的任意位置添加：required符号，如下所示：
opts.on("-f", "--foo [Bar]", String, :required, "Some required option") do |option|
@options[:foo] = option
end
然后在OptionParser块的末尾添加其中一个以打印丢失的开关和使用说明：
if opts.missing_switches?
puts opts.missing_switches
puts opts
exit
end
最后，为了完成所有工作，您需要将以下“optparse_required_switches.rb”文件添加到您的项目中，并在执行命令行解析时需要它。
我在博客上写了一篇小例子，上面有一个例子： http://picklepumpers.com/wordpress/?p=949
这是修改后的OptionParser文件及其用法示例：
<强> required_switches_example.rb
#!/usr/bin/env ruby
require 'optparse'
require_relative 'optparse_required_switches'
# Configure options based on command line options
@options = {}
OptionParser.new do |opts|
opts.banner = "Usage: test [options] in_file[.srt] out_file[.srt]"
# Note that :required can be anywhere in the parameters
# Also note that OptionParser is bugged and will only check
# for required parameters on the last option, not my bug.
# required switch, required parameter
opts.on("-s Short", String, :required, "a required switch with just a short") do |operation|
@options[:operation] = operation
end
# required switch, optional parameter
opts.on(:required, "--long [Long]", String, "a required switch with just a long") do |operation|
@options[:operation] = operation
end
# required switch, required parameter
opts.on("-b", "--both ShortAndLong", String, "a required switch with short and long", :required) do |operation|
@options[:operation] = operation
end
# optional switch, optional parameter
opts.on("-o", "--optional [Whatever]", String, "an optional switch with short and long") do |operation|
@options[:operation] = operation
end
# Now we can see if there are any missing required
# switches so we can alert the user to what they
# missed and how to use the program properly.
if opts.missing_switches?
puts opts.missing_switches
puts opts
exit
end
end.parse!
<强> optparse_required_switches.rb
# Add required switches to OptionParser
class OptionParser
# An array of messages describing the missing required switches
attr_reader :missing_switches
# Convenience method to test if we're missing any required switches
def missing_switches?
!@missing_switches.nil?
end
def make_switch(opts, block = nil)
short, long, nolong, style, pattern, conv, not_pattern, not_conv, not_style = [], [], []
ldesc, sdesc, desc, arg = [], [], []
default_style = Switch::NoArgument
default_pattern = nil
klass = nil
n, q, a = nil
# Check for required switches
required = opts.delete(:required)
opts.each do |o|
# argument class
next if search(:atype, o) do |pat, c|
klass = notwice(o, klass, 'type')
if not_style and not_style != Switch::NoArgument
not_pattern, not_conv = pat, c
else
default_pattern, conv = pat, c
end
end
# directly specified pattern(any object possible to match)
if (!(String === o || Symbol === o)) and o.respond_to?(:match)
pattern = notwice(o, pattern, 'pattern')
if pattern.respond_to?(:convert)
conv = pattern.method(:convert).to_proc
else
conv = SPLAT_PROC
end
next
end
# anything others
case o
when Proc, Method
block = notwice(o, block, 'block')
when Array, Hash
case pattern
when CompletingHash
when nil
pattern = CompletingHash.new
conv = pattern.method(:convert).to_proc if pattern.respond_to?(:convert)
else
raise ArgumentError, "argument pattern given twice"
end
o.each {|pat, *v| pattern[pat] = v.fetch(0) {pat}}
when Module
raise ArgumentError, "unsupported argument type: #{o}", ParseError.filter_backtrace(caller(4))
when *ArgumentStyle.keys
style = notwice(ArgumentStyle[o], style, 'style')
when /^--no-([^\[\]=\s]*)(.+)?/
q, a = $1, $2
o = notwice(a ? Object : TrueClass, klass, 'type')
not_pattern, not_conv = search(:atype, o) unless not_style
not_style = (not_style || default_style).guess(arg = a) if a
default_style = Switch::NoArgument
default_pattern, conv = search(:atype, FalseClass) unless default_pattern
ldesc << "--no-#{q}"
long << 'no-' + (q = q.downcase)
nolong << q
when /^--\[no-\]([^\[\]=\s]*)(.+)?/
q, a = $1, $2
o = notwice(a ? Object : TrueClass, klass, 'type')
if a
default_style = default_style.guess(arg = a)
default_pattern, conv = search(:atype, o) unless default_pattern
end
ldesc << "--[no-]#{q}"
long << (o = q.downcase)
not_pattern, not_conv = search(:atype, FalseClass) unless not_style
not_style = Switch::NoArgument
nolong << 'no-' + o
when /^--([^\[\]=\s]*)(.+)?/
q, a = $1, $2
if a
o = notwice(NilClass, klass, 'type')
default_style = default_style.guess(arg = a)
default_pattern, conv = search(:atype, o) unless default_pattern
end
ldesc << "--#{q}"
long << (o = q.downcase)
when /^-(\[\^?\]?(?:[^\\\]]|\\.)*\])(.+)?/
q, a = $1, $2
o = notwice(Object, klass, 'type')
if a
default_style = default_style.guess(arg = a)
default_pattern, conv = search(:atype, o) unless default_pattern
end
sdesc << "-#{q}"
short << Regexp.new(q)
when /^-(.)(.+)?/
q, a = $1, $2
if a
o = notwice(NilClass, klass, 'type')
default_style = default_style.guess(arg = a)
default_pattern, conv = search(:atype, o) unless default_pattern
end
sdesc << "-#{q}"
short << q
when /^=/
style = notwice(default_style.guess(arg = o), style, 'style')
default_pattern, conv = search(:atype, Object) unless default_pattern
else
desc.push(o)
end
end
default_pattern, conv = search(:atype, default_style.pattern) unless default_pattern
if !(short.empty? and long.empty?)
s = (style || default_style).new(pattern || default_pattern, conv, sdesc, ldesc, arg, desc, block)
elsif !block
if style or pattern
raise ArgumentError, "no switch given", ParseError.filter_backtrace(caller)
end
s = desc
else
short << pattern
s = (style || default_style).new(pattern, conv, nil, nil, arg, desc, block)
end
# Make sure required switches are given
if required && !(default_argv.include?("-#{short[0]}") || default_argv.include?("--#{long[0]}"))
@missing_switches ||= [] # Should be placed in initialize if incorporated into Ruby proper
# This is more clear but ugly and long.
#missing = "-#{short[0]}" if !short.empty?
#missing = "#{missing} or " if !short.empty? && !long.empty?
#missing = "#{missing}--#{long[0]}" if !long.empty?
# This is less clear and uglier but shorter.
missing = "#{"-#{short[0]}" if !short.empty?}#{" or " if !short.empty? && !long.empty?}#{"--#{long[0]}" if !long.empty?}"
@missing_switches << "Missing switch: #{missing}"
end
return s, short, long,
(not_style.new(not_pattern, not_conv, sdesc, ldesc, nil, desc, block) if not_style),
nolong
end
end
答案 3 :(得分：6)
我想出了一个简明扼要的解决方案，总结了你的贡献。它将缺少的参数作为消息引发OptionParser::MissingArgument异常。 rescue块中包含此异常以及来自OptionParser的其他异常。
#!/usr/bin/env ruby
require 'optparse'
options = {}
optparse = OptionParser.new do |opts|
opts.on('-h', '--host hostname', "Host name") do |host|
options[:host] = host
end
end
begin
optparse.parse!
mandatory = [:host]
missing = mandatory.select{ |param| options[param].nil? }
raise OptionParser::MissingArgument, missing.join(', ') unless missing.empty?
rescue OptionParser::ParseError => e
puts e
puts optparse
exit
end
运行此示例：
./program
missing argument: host
Usage: program [options]
-h, --host hostname Host name
答案 4 :(得分：4)
如果需要主机，那么肯定它不是选项，它是参数。
考虑到这一点，这是一种解决问题的方法。您可以询问ARGV数组以查看是否已指定主机，如果尚未指定主机，则调用abort("You must specify a host!")或类似内容，以使程序退出并显示错误状态。< / p>
答案 5 :(得分：2)
如果您这样做：
opts.on('-h', '--host',
'required host name [STRING]') do |h|
someoptions[:host] = h || nil
end
然后someoptions[:host]将是来自命令行的值或nil（如果你在--host之后没有提供--host和/或没有值）你可以测试它解析后很容易（有条件地失败）：
fail "Hostname not provided" unless someoptions[:host]
答案 6 :(得分：1)
来自未知（谷歌）的答案很好，但包含一个小错误。
rescue OptionParser::InvalidArgument, OptionParser::MissingArgument
应该是
OptionParser::InvalidOption, OptionParser::MissingArgument
否则，optparse.parse!将触发OptionParser::InvalidOption的标准错误输出，而不是自定义消息。
答案 7 :(得分：1)
我们的想法是定义OptionParser，然后定义parse!，如果某些字段缺失，则puts。默认情况下将filename设置为空字符串可能不是最佳方法，但您明白了。
require 'optparse'
filename = ''
options = OptionParser.new do |opts|
opts.banner = "Usage: swift-code-style.rb [options]"
opts.on("-iNAME", "--input-filename=NAME", "Input filename") do |name|
filename = name
end
opts.on("-h", "--help", "Prints this help") do
puts opts
exit
end
end
options.parse!
if filename == ''
puts "Missing filename.\n---\n"
puts options
exit
end
puts "Processing '#{filename}'..."
如果缺少-i filename，则会显示：
~/prj/gem/swift-code-kit ./swift-code-style.rb
Missing filename.
---
Usage: swift-code-style.rb [options]
-i, --input-filename=NAME Input filename
-h, --help Prints this help