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## groovy.util
[Groovy] Class CliBuilder

    java.lang.Object
      groovy.util.CliBuilder

    class CliBuilder
    extends Object

Provides a builder to assist the processing of command line arguments.

Typical usage (emulate partial arg processing of unix command: ls -alt *.groovy):

     def cli = new CliBuilder(usage:'ls')
     cli.a('display all files')
     cli.l('use a long listing format')
     cli.t('sort by modification time')
     def options = cli.parse(args)
     assert options // would be null (false) on failure
     assert options.arguments() == ['*.groovy']
     assert options.a && options.l && options.t

The usage message for this example (obtained using `cli.usage()`) is shown below:

     usage: ls
      -a   display all files
      -l   use a long listing format
      -t   sort by modification time

An underlying parser that supports what is called argument 'bursting' is used by default. Bursting would convert '-alt' into '-a -l -t' provided no long option exists with value 'alt' and provided that none of 'a', 'l' or 't' takes an argument (in fact the last one is allowed to take an argument). The bursting behavior can be turned off by using an alternate underlying parser. The simplest way to achieve this is by setting the posix property on the CliBuilder to false, i.e. include `posix: false` in the constructor call.

Another example (partial emulation of arg processing for 'ant' command line):

     def cli = new CliBuilder(usage:'ant [options] [targets]',
                              header:'Options:')
     cli.help('print this message')
     cli.logfile(args:1, argName:'file', 'use given file for log')
     cli.D(args:2, valueSeparator:'=', argName:'property=value',
           'use value for given property')
     def options = cli.parse(args)
     ...

Usage message would be:

     usage: ant [options] [targets]
     Options:
      -D <property=value>   use value for given property
      -help                 print this message
      -logfile <file>       use given file for log

And if called with the following arguments '-logfile foo -Dbar=baz target' then the following assertions would be true:

     assert options // would be null (false) on failure
     assert options.arguments() == ['target']
     assert options.Ds == ['bar', 'baz']
     assert options.logfile == 'foo'

Note the use of some special notation. By adding 's' onto an option that may appear multiple times and has an argument or as in this case uses a valueSeparator to separate multiple argument values causes the list of associated argument values to be returned.

Another example showing long options (partial emulation of arg processing for 'curl' command line):

     def cli = new CliBuilder(usage:'curl [options] <url>')
     cli._(longOpt:'basic', 'Use HTTP Basic Authentication')
     cli.d(longOpt:'data', args:1, argName:'data', 'HTTP POST data')
     cli.G(longOpt:'get', 'Send the -d data with a HTTP GET')
     cli.q('If used as the first parameter disables .curlrc')
     cli._(longOpt:'url', args:1, argName:'URL', 'Set URL to work with')

Which has the following usage message:

     usage: curl [options] <url>
         --basic         Use HTTP Basic Authentication
      -d,--data <data>   HTTP POST data
      -G,--get           Send the -d data with a HTTP GET
      -q                 If used as the first parameter disables .curlrc
         --url <URL>     Set URL to work with

This example shows a common convention. When mixing short and long names, the short names are often one character in size. One character options with arguments don't require a space between the option and the argument, e.g. `-Ddebug=true`. The example also shows the use of '_' when no short option is applicable.

Also note that '_' was used multiple times. This is supported but if any other shortOpt or any longOpt is repeated, then the behavior is undefined.

Short option names may not contain a hyphen. If a long option name contains a hyphen, e.g. '--max-wait' then you can either use the long hand method call `options.hasOption('max-wait')` or surround the option name in quotes, e.g. `options.'max-wait'`.

Although CliBuilder on the whole hides away the underlying library used for processing the arguments, it does provide some hooks which let you make use of the underlying library directly should the need arise. For example, the last two lines of the 'curl' example above could be replaced with the following:

     import org.apache.commons.cli.*
     ... as before ...
     cli << new Option('q', false, 'If used as the first parameter disables .curlrc')
     cli << OptionBuilder.withLongOpt('url').hasArg().withArgName('URL').
                          withDescription('Set URL to work with').create()
     ...

CliBuilder also supports Argument File processing. If an argument starts with an '@' character followed by a filename, then the contents of the file with name filename are placed into the command line. The feature can be turned off by setting expandArgumentFiles to false. If turned on, you can still pass a real parameter with an initial '@' character by escaping it with an additional '@' symbol, e.g. '@@foo' will become '@foo' and not be subject to expansion. As an example, if the file temp.args contains the content:

     -arg1
     paramA
     paramB paramC

Then calling the command line with:

     someCommandtemp.args:-arg2 paramD

Is the same as calling this:

     someCommand -arg1 paramA paramB paramC -arg2 paramD

This feature is particularly useful on operating systems which place limitations on the size of the command line (e.g. Windows). The feature is similar to the 'Command Line Argument File' processing supported by javadoc and javac. Consult the corresponding documentation for those tools if you wish to see further examples.

Supported Option Properties:

       argName:        String
       longOpt:        String
       args:           int
       optionalArg:    boolean
       required:       boolean
       type:           Object (not currently used)
       valueSeparator: char

See Option for the meaning of these properties and CliBuilderTest for further examples.

Authors:
  Dierk Koenig
  Paul King

Property Summary
`boolean` | `expandArgumentFiles` Whether arguments of the form '`@`filename' will be expanded into the arguments contained within the file named filename (default true).
`String` | `footer` Optional additional message for usage; displayed after the options are displayed.
`HelpFormatter` | `formatter` Normally set internally but can be overridden if you want to customise how the usage message is displayed.
`String` | `header` Optional additional message for usage; displayed after the usage summary but before the options are displayed.
`Options` | `options` Not normally accessed directly but full access to underlying options if needed.
`CommandLineParser` | `parser` Normally set internally but allows you full customisation of the underlying processing engine.
`boolean` | `posix` To change from the default PosixParser to the GnuParser, set this to false.
`boolean` | `stopAtNonOption` Indicates that option processing should continue for all arguments even if arguments not recognized as options are encountered (default true).
`String` | `usage` Usage summary displayed as the first line when `cli.usage()` is called.
`int` | `width` Allows customisation of the usage message width.
`PrintWriter` | `writer` Defaults to stdout but you can provide your own PrintWriter if desired.

Method Summary
`static def` | `expandArgumentFiles(def args)`
`def` | `invokeMethod(String name, Object args)` Internal method: Detect option specification method calls.
`Option` | `option(def shortname, Map details, def info)` Internal method: How to create an option from the specification.
`OptionAccessor` | `parse(def args)` Make options accessible from command line args with parser (default: Posix).
`void` | `usage()` Print the usage message with writer (default: System.out) and formatter (default: HelpFormatter)

Methods inherited from class Object
wait, wait, wait, equals, toString, hashCode, getClass, notify, notifyAll

Property Detail

### expandArgumentFiles

    boolean expandArgumentFiles

  Whether arguments of the form '`@`filename' will be expanded into the arguments contained within the file named filename (default true).

### footer

    String footer

  Optional additional message for usage; displayed after the options are displayed.

### formatter

    HelpFormatter formatter

  Normally set internally but can be overridden if you want to customise how the usage message is displayed.

### header

    String header

  Optional additional message for usage; displayed after the usage summary but before the options are displayed.

### options

    Options options

  Not normally accessed directly but full access to underlying options if needed.

### parser

    CommandLineParser parser

  Normally set internally but allows you full customisation of the underlying processing engine.

### posix

    boolean posix

  To change from the default PosixParser to the GnuParser, set this to false. Ignored if the parser is explicitly set.

### stopAtNonOption

    boolean stopAtNonOption

  Indicates that option processing should continue for all arguments even if arguments not recognized as options are encountered (default true).

### usage

    String usage

  Usage summary displayed as the first line when `cli.usage()` is called.

### width

    int width

  Allows customisation of the usage message width.

### writer

    PrintWriter writer

  Defaults to stdout but you can provide your own PrintWriter if desired.

Method Detail

### expandArgumentFiles

    static def expandArgumentFiles(def args)

### invokeMethod

    def invokeMethod(String name, Object args)

  Internal method: Detect option specification method calls.

### option

    Option option(def shortname, Map details, def info)

  Internal method: How to create an option from the specification.

### parse

    OptionAccessor parse(def args)

  Make options accessible from command line args with parser (default: Posix). Returns null on bad command lines after displaying usage message.

### usage

    void usage()

  Print the usage message with writer (default: System.out) and formatter (default: HelpFormatter)

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