NAME
    Getopt::Complete - programmable shell completion for Perl apps

VERSION
    This document describes Getopt::Complete v0.9.

SYNOPSIS
    In the Perl program "myprogram":

      use Getopt::Complete (
          'frog'        => ['ribbit','urp','ugh'],
          'fraggle'     => sub { return ['rock','roll'] },
          'quiet!'      => undef,
          'name'        => undef,
          'age=n'       => undef,
          'outfile=s@'  => 'files', 
          'outdir'      => 'directories'
          'runthis'     => 'commands',
          'username'    => 'users',
          '<>'          => 'directories', 
      );

      print "the frog says " . $ARGS{frog} . "\n";

    In ~/.bashrc or ~/.bash_profile, or directly in bash:

      complete -C myprogram myprogram

    Thereafter in the terminal (after next login, or sourcing the updated
    .bashrc):

      $ myprogram --f<TAB>
      $ myprogram --fr

      $ myprogram --fr<TAB><TAB>
      frog fraggle

      $ myprogram --fro<TAB>
      $ myprogram --frog 

      $ myprogram --frog <TAB>
      ribbit urp ugh

      $ myprogram --frog r<TAB>
      $ myprogram --frog ribbit

DESCRIPTION
    This module makes it easy to add custom command-line completion to Perl
    applications. It also does additional validation of arguments, when the
    program is actually executed, based on completion lists.

    Support is also present for apps which are an entry point for a
    hierarchy of sub-commands (in the style of cvs and git).

    Getopt::Complete also wraps the standard options processing and exports
    it as a %ARGS hash at compile time, making using the arguments
    hassle-free.

    The completion features currently work with the bash shell, which is the
    default on most Linux and Mac systems. Patches for other shells are
    welcome.

OPTIONS PROCESSING
    Getopt::Complete processes the command-line options at compile time.

    The results are avaialble in the %ARGS hash, which is intended as a
    companion to the @ARGV array generated natively by Perl.

      use Getopt::Complete (
        'mydir'     => 'd',
        'myfile'    => 'f',
        '<>'        =  ['monkey', 'taco', 'banana']
      );

      for $opt (keys %ARGS) {
        $val = $ARGS{$opt};
        print "$opt has value $val\n";
      }

    Errors in shell argumentes result in messages to STDERR via warn(), and
    cause the program to exit during "use" call. Getopt::Complete verifies
    that the option values specified match their own completion list, and
    will otherwise add additional errors explaining the problem.

    The %ARGS hash is an alias for %Getopt::Complete::ARGS. The alias is not
    created in the caller's namespaces if a hash named %ARGS already exists
    with data, but the results are always available from
    %Getopt::Complete::ARGS.

    They keys of the hash are the option names, minus any specifiers like
    "=s" or "!". The key is only present if the option was specified on the
    command-line.

    The values of the hash are the values from the command-line. For
    multi-value options the hash value is an arrayref.

OBJECT API
    An object $ARGS is also created in the caller's namespace (class
    Getopt::Complete::Args) with a more detailed API for argument
    interrogation. See the documentation for that module, and also for the
    underlying Getopt::Complete::Options module.

    It is possible to override any part of the default process, including
    doing custom parsing, doing processing at run-time, and and preventing
    exit when there are errors.

    See OVERRIDING COMPILE-TIME OPTION PARSING for more information.

PROGRAMMABLE COMPLETION BACKGROUND
    The bash shell supports smart completion of words when the <TAB> key is
    pressed. By default, after the program name is specified, bash will
    presume the word the user is typing a is a file name, and will attempt
    to complete the word accordingly. Where completion is ambiguous, the
    shell will go as far as it can and beep. Subsequent completion attempts
    at that position result in a list being shown of possible completions.

    Bash can be configured to run a specific program to handle the
    completion task, allowing custom completions to be done for different
    appliations. The "complete" built-in bash command instructs the shell
    as-to how to handle tab-completion for a given command.

    This module allows a program to be its own word-completer. It detects
    that the COMP_LINE and COMP_POINT environment variables are set,
    indicating that it is being used as a completion program, and responds
    by returning completion values suitable for the shell _instead_ of
    really running the application.

    See the manual page for "bash", the heading "Programmable Completion"
    for full details on the general topic.

HOW TO CONFIGURE PROGRAMMABLE COMPLETION
    1   Put a "use Getopt::Complete" statement into your app as shown in the
        synopsis. The key-value pairs describe the command-line options
        available, and their completions.

        This should be at the TOP of the app, before any real processing is
        done. The only modules used before it should be those needed for
        custom callbacks, if there are any. No code should print to standard
        output during compile time, or it will confuse bash.

        Subsequent code can use %ARGS or the $ARGS object to check on
        command-line option values.

        Existing apps using Getopt::Long should use their option spec in the
        use declaration instead. If they bind variables directly the code
        should to be updated to get values from the %ARGS hash instead.

    2   Put the following in your .bashrc or .bash_profile:

          complete -C myprogram myprogram

        For the very conservative, do this (to ensure nothing runs during
        completion checks):

          complete -C 'perl -c myprogram 2>/dev/null' myprogram

    3   New logins will automatically run the above and become aware that
        your program has programmable completion. For shells you already
        have open, run this to alert bash to your that your program has
        custom tab-completion.

          source ~/.bashrc 

    Type the name of your app ("myprogram" in the example), and experiment
    with using the <TAB> key to get various completions to test it. Every
    time you hit <TAB>, bash sets certain environment variables, and then
    runs your program. The Getopt::Complete module detects these variables,
    responds to the completion request, and then forces the program to exit
    before really running your regular application code.

    IMPORTANT: Do not do steps #2 and #3 w/o doing step #1, or your
    application will actually run "normally" every time you press <TAB> with
    it on the command-line! The module will not be present to detect that
    this is not a "real" execution of the program, and you may find your
    program is running when it should not.

KEYS IN THE OPTIONS SPECIFICATION
    Each key in the list decribes an option which can be completed. Any key
    usable in a Getopt:::Long GetOptions specification works here, (except
    as noted in BUGS below):

    an option name
        A normal word is interpreted as an option name. The '=s' specifier
        is presumed if no specifier is present.

          'p1' => [...]

    a complete option specifier
        Any specification usable by Getopt::Long is valid as the key. For
        example:

          'p1=s' => [...]       # the same as just 'p1'
          'p2=s@' => [...]      # expect multiple values

    the '<>' symbol for "bare arguments"
        This special key specifies how to complete non-option (bare)
        arguments. It presumes multiple values are possible (like '=s@'):

        Have an explicit list: '<>' = ['value1','value2','value3']

        Do normal file completion: '<>' = 'files'

        Take arbitrary values with no expectations: '<>' = undef

        If there is no '<>' key specified, bare arguments will be treated as
        an error.

    a sub-command specifier, starting with '>'
        When a key in the options specification starts with '>', it
        indicates a that word maps to a distinct sub-command with its own
        options. The array to the right is itself a full options
        specification, following the same format as the one above it,
        including possible further sub-commands.

        See SUB-COMMAND TREES for more details.

VALUES IN THE OPTIONS SPECIFICATION
    Each value describes how the option in question should be completed.

    array reference
        An array reference expliciitly lists the valid values for the
        option.

          In the app:

            use Getopt::Complete (
                'color'    => ['red','green','blue'],
            );

          In the shell:

            $ myprogram --color <TAB>
            red green blue

            $ myprogram --color blue
            (runs with no errors)

        The list of value is also used to validate the user's choice after
        options are processed:

            myprogram --color purple
            ERROR: color has invalid value purple: select from red green blue

        See below for details on how to permit values which aren't shown in
        completions to be used and not generate errors.

    undef
        An undefined value indicates that the option is not completable. No
        completions will be offered by the application, though any value
        provided by the user will be considered valid.

        Note that this is distinct from returning an empty arrayref from a
        callback, which implies that there ARE known completions but the
        user has failed to match any of them.

        Also note: this is the only valid completion for boolean parameters,
        since there is no value to specify on the command-line.

          use Getopt::Complete (
            'name'      => undef,   # take --name "anyting" 
            'perky!'    => undef,   # take --perky or --no-perky
          );

    subroutine callback
        When the list of valid values must be determined dynamically, a
        subroutine reference or name can be specified. If a name is
        specified, it should be fully qualified. (If it is not, it will be
        presumed to refer to one of the bash builtin completions types. See
        BUILTIN COMPLETION TYPES below.)

        The subroutine will be called, and is expected to return an arrayref
        of possiible matches. The arrayref will be treated as though it were
        specified directly in the specification.

        As with explicit values, an empty arrayref indicated that there are
        no valid matches for this option, given the other params on the
        command-line, and the text already typed. An undef value indicates
        that any value is valid for this parameter.

        Parameters to the callback are described below.

WRITING SUBROUTINE CALLBACKS
    A subroutine callback is useful when the list of options to match must
    be dynamically generated.

    It is also useful when knowing what the user has already typed helps
    narrow the search for valid completions, or when iterative completion
    needs to occur (see PARTIAL COMPLETIONS below).

    The callback is expected to return an arrayref of valid completions. If
    it is empty, no completions are considered valid. If an undefined value
    is returned, no completions are specified, but ANY arbitrary value
    entered is considered valid as far as error checking is concerned.

    The callback registerd in the completion specification will receive the
    following parameters:

    command name
        Contains the name of the command for which options are being parsed.
        This is $0 in most cases, though hierarchical commands may have a
        name "svn commit" or "foo bar baz" etc.

    current word
        This is the word the user is trying to complete. It may be an empty
        string, if the user hits <Tab> without typing anything first.

    option name
        This is the name of the option for which we are resolving a value.
        It is typically ignored unless you use the same subroutine to
        service multiple options.

        A value of '<>' indicates an unnamed argument (a.k.a "bare argument"
        or "non-option" argument).

    other opts
        It is the hashref resulting from Getopt::Long processing of all of
        the OTHER arguments. This is useful when one option limits the valid
        values for another option.

        In some cases, the options which should be available change
        depending on what other options are present, or the values available
        change depending on other options or their values.

    The environment variables COMP_LINE and COMP_POINT have the exact text
    of the command-line and also the exact character position, if more
    detail is needed in raw form than the parameters provide.

    The return value is a list of possible matches. The callback is free to
    narrow its results by examining the current word, but is not required to
    do so. The module will always return only the appropriate matches.

  EXAMPLE
    This app takes 2 parameters, one of which is dependent on the other:

      use Getopt::Complete (
        type => ['names','places','things'],
        instance => sub {
                my ($command, $value, $option, $other_opts) = @_;
                if ($other_opts{type} eq 'names') {
                    return [qw/larry moe curly/],
                }
                elsif ($other_opts{type} eq 'places') {
                    return [qw/here there everywhere/],
                }
                elsif ($other_opts{type} eq 'things') {
                    return [ query_database_matching("${value}%") ]
                }
                elsif ($otper_opts{type} eq 'surprsing') {
                    # no defined list: take anything typed
                    return undef;
                }
                else {
                    # invalid type: no matches
                    return []
                }
            }
       );

       $ myprogram --type people --instance <TAB>
       larry moe curly

       $ myprogram --type places --instance <TAB>
       here there everywhere

       $ myprogram --type surprising --instance <TAB>
       (no completions appear)   

BUILTIN COMPLETIONS
    Bash has a list of built-in value types which it knows how to complete.
    Any of the default shell completions supported by bash's "compgen" are
    supported by this module.

    The list of builtin types supported as-of this writing are:

        files
        directories
        commands
        users
        groups
        environment
        services
        aliases
        builtins

    To indicate that an argument's valid values are one of the above, use
    the exact string after Getopt::Complete:: as the completion callback.
    For example:

      use Getopt::Complete (
        infile  => 'Getopt::Complete::files',       
        outdir  => 'Getopt::Complete::directories', 
        myuser  => 'Getopt::Complete::users',
      );

    The full name is alissed as the single-character compgen parameter name
    for convenience. Further, because Getopt::Complete is the default
    namespace during processing, it can be ommitted from callback function
    names.

    The following are all equivalent. They effectively produce the same list
    as 'compgen -f':

       file1 => \&Getopt::Complete::files
       file1 => \&Getopt::Complete::f
       file1 => 'Getopt::Complete::files'
       file1 => 'Getopt::Complete::f'
       file1 => 'files'
       file1 => 'f'

    See Getopt::Complete::Compgen for specifics on using builtin
    completions.

    See "man bash", in the Programmable Complete secion, and the "compgen"
    builtin command for more details.

UNLISTED VALID VALUES
    If there are options which should not be part of completion lists, but
    still count as valid if passed-into the app, they can be in a final
    sub-array at the end. This list doesn't affect the completion system at
    all, just prevents errors in the ERRORS array described above.

        use Getopt::Complete (
            'color'    => ['red','green','blue', ['yellow','orange']],
        );

        myprogram --color <TAB>
        red green blue

        myprogram --color orange
        # no errors

        myprogram --color purple
        # error
    
PARTIAL COMPLETIONS
  BASICS
        Any returned value ending in a <TAB> character ("\t") will be
        considered a "partial" completion. This means that the shell will be
        instructed to leave the cursor at the end of that word even if there
        is no ambiguity in the rest of the returned list.

        Partial completions are only usable from callbacks. From a
        hard-coded array of values, it would be impossible to ever fuly
        complete the partial completion.

  BACKGROUND
        Sometimes, the entire list of completions is too big to reasonable
        resolve and return. The most obvious example is filename completion
        at the root of a large filesystem. In these cases, the completion of
        is handled in pieces, allowing the user to gradually "drill down" to
        the complete value directory by directory. It is even possible to
        hit <TAB> to get one completion, then hit it again and get more
        completion, in the case of single-sub-directory directories.

        The Getopt::Complete module supports iterative drill-down
        completions from any parameter configured with a callback. It is
        completely valid to complete "a" with "aa" "ab" and "ac", but then
        to complete "ab" with yet more text.

        Unless the shell knows, however that your "aa", "ab", and "ac"
        completions are in fact only partial completions, an inconvenient
        space will be added after the word on the terminal line, as the
        shell happily moves on to helping the user enter the next argument.

  DETAILS
        Because partial completions are indicated in Getopt::Complete by
        adding a "\t" tab character to the end of the returned string, an
        application can return a mix of partial and full completions, and it
        will respect each correctly.

        Note: The "\t" is actually stripped-off before going to the shell
        and internal hackery is used to force the shell to not put a space
        where it isn't needed. This is not part of the bash programmable
        completion specification, but is used to simulate features typically
        only available with bash for builtin completions like
        files/directories.

SUB-COMMAND TREES
    It is common for a given appliction to actually be an entry point for
    several different tools. Popular exmples are the big version control
    suites (cvs,svn,svk,git), which use the form:

     cvs SUBCOMMAND [ARGS]

    Each sub-command has its own options specification. Those may in turn
    have further sub-commands.

    Sub-commands are identified by an initial '>' in the options
    specification key. The value is interpreted as a complete, isolated
    options spec, using the same general syntax. This applies recursively.

  EXAMPLE COMMAND TREE SPEC
        use Getopt::Complete (
            '>animal' => [
                '>dog' => [
                    '>bark' => [
                        'ferocity'  => ['yip','wail','ruf','grrrr'], 
                        'count'  => ['1','2','one too many'], 
                    ],
                    '>drool' => [
                        'buckets=n' => undef, 
                        'lick'      => 'users', 
                    ],
                    'list!' => undef,
                ],
                '>cat' => [
                    '>purr' => [],
                    '>meow' => [ 
                        'volume=n' => undef,
                        'bass' => ['low','medium','high'],
                    ]
                ],
            ],
            '>plant' => [
                '>taters' => [
                    '>fry' => [
                        'greasiness'    => ['crispy','drippy'],
                        'width'         => ['fat','thin','frite'],
                    ],
                    '>bake' => [
                        'hard!'     => undef,
                        'temp=n'    => undef,
                    ],
                ],
                '>dasies' => [
                    '>pick' => [
                        '<>'            => ['mine','yours','theirs'],
                    ],
                    '>plant' => [
                        'season'        => ['winter','spring','summer','fall'],
                        'seeds=n'       => undef,
                        'deep!'         => undef,
                    ]
                ]
            ]
        );

        my ($word1,$word2,$word3) = $ARGS->parent_sub_commands; 
        # (the above is also in $ARGS{'>'} for non-OO access)

        # your program probably has something smarter to decide where to go 
        # for a given command
        if ($word1 eq 'animal') {
            if ($word2 eq 'dog') {
                if ($word3 eq 'bark') {
                    # work with %ARGS for barking dogs...
                    # ....
                }
            }
        }
        elsif ($path[0] eq 'plant') {
            ...
        }

    The above example specifies two sub-commands "animal" and "plant, each
    of which has its own two sub-commands, dog/cat and taters/dasies. Each
    of those, in turn, have two sub-commands, for a total of 8 complete
    commands possible, each with different arguments. Each of the 8 has
    thier own options specification.

    When the program executes, the %ARGS hash contains option/value pairs
    for the specific command chosen. The the series of sub-command choices
    in $ARGS{'>'}, separate from the regular bare arguments in '<>'. (The
    method name on an $ARGS object for this is "parent_sub_commands", a
    companion to the "bare_args" method.

    The method to determine the next available sub-commands is just
    "sub_commands".)

    Note that, since the user can hit <ENTER> at any time, it is possible
    that the parent_sub_commands will be a partial drill-down. It isn't
    uncommon to have something like this in place:

     if (my @next = $ARGS->sub_commands) {
        print STDERR "Please select a sub-command:\n";
        print STDERR join("\n", @sub_commands),"\n";
        exit 1;
     }

    The above checking is not done automatically, since a sub-command may
    have further sub-commands, but still also be used directly, possibly
    with other option and bare arguments.

THE LONE DASH
    A lone dash is often used to represent using STDIN instead of a file for
    applications which otherwise take filenames.

    This is supported by all options which complete with the "files"
    builtin, though it does not appear in completion hint displays.

    To disable this, set $Getopt::Complete::LONE_DASH = 0.

OVERRIDING COMPILE-TIME OPTION PARSING
    Getopt::Complete makes a lot of assumptions in order to be easy to use
    in the default case. Here is how to override that behavior if it's not
    what you want.

  OPTION 1: DOING CUSTOM ERROR HANDLING
        To prevent Getopt::Complete from exiting at compile time if there
        are errors, the EXIT_ON_ERRORS flag should be set to 0 first, at
        compile time, before using the Getopt::Complete module as follows:

         BEGIN { $Getopt:Complete::EXIT_ON_ERRORS = 0; }

        This should not affect completions in any way (it will still exit if
        it realizes it is talking to bash, to prevent accidentally running
        your program).

        Errors are retained in:

         $Getopt::Complete::ARGS->errors;

        It is then up to the application to not run with invalid parameters.

  OPTION 2: RE-PROCESS @ARGV
        This module restores @ARGV to its original state after processing,
        so independent option processing can be done if necessary. The full
        spec imported by Getopt::Complete is stored as:

         $Getopt::Complete::ARGS->option_specs;

        This is an easy option when upgrading old applications.

        Combined with disabling the EXIT_ON_ERROS flag above, set, you can
        completely ignore, or partially ignore, the options processing which
        happens automatically.

  OPTION 3: CHANGING COMPILE-TIME PROCESSING
        You can also adjust how option processing happens inside of
        Getopt::Complete. Getopt::Complete wraps Getopt::Long to do the
        underlying option parsing. It uses GetOptions(\%h, @specification)
        to produce the %ARGS hash. Customization of Getopt::Long should
        occur in a BEGIN block before using Getopt::Complete.

  OPTION 4: USE THE OBJECTS AND WRITE YOUR OWN LOGIC
        The logic in import() is very short, and is simple to modify. It is
        best to do it in a BEGIN {} block so that bash can use 'perl -c
        myprogram' to get completions at compile time.

            BEGIN {

                my $options = Getopt::Complete::Options->new(
                    'myfile' => 'f',
                    'mychoice' => ['small','medium','huge']
                );

                $options->handle_shell_completion();

                my $args = Getopt::Complete::Args->new(
                    options => $options,
                    argv => [@ARGV]
                );
        
                if (my @errors = $ARGS->errors) {
                    for my $error ($ARGS->errors) {
                        chomp $error;
                        warn __PACKAGE__ . ' ERROR:' . $error . "\n";
                    }
                    exit 1;
                }
    
                # make the %ARGS available to all of the app
                $args->__install_as_default__;

                # if you also want %ARGS and $ARGS here when you're finished...
                Getopt:Complete->export_aliases(__PACKAGE__);
            };

EXTENSIVE USAGE EXAMPLE
    Cut-and-paste this into a script called "myprogram" in your path, make
    it executable, and then run this in the shell: complete -C myprogram
    myprogram. Then try it out. It does one of everything, besides command
    trees.

        #!/usr/bin/env perl
        use strict;
        use warnings;

        use Getopt::Complete (
            # list the explicit values which are valid for this option
            'frog'    => ['ribbit','urp','ugh'],

            # you can add any valid Getopt::Long specification to the key on the left
            # ...if you put nothing: "=s" is assumed
            'names=s@' => ['eenie','meanie','miney'],

            # support for Bash "compgen" builtins is present with some pre-made callbacks
            'myfile'    => 'Getopt::Complete::Compgen::files',
            'mydir'     => 'Getopt::Complete::Compgen::directories',
        
            # the plain name or first letter of the compgen builtins also work
            'myfile2'   => 'files',
            'myfile3'   => 'f',

            # handle unnamed arguments from the command-line ("non-option" arguments) with a special key:
            '<>'      => ['some','raw','words'],

            # CODE callbacks allow a the completion list to be dynamically resolved 
            'fraggle' => sub { return ['rock','roll','fried fish','fried taters','fries and squid'] },

            # callbacks get extra info to help them, including the part of the
            # word already typed, and the remainder of the options already processed for context
            'type'    => ['people','places'],
            'instance'=> sub {
                                my ($command, $partial_word, $option_name, $other_opts_hashref) = @_;
                                # be lazy and ignore the partial word: bash will compensate
                                if (my $type = $other_opts_hashref->{type}) {
                                    if ($type eq 'people') {
                                        return [qw/larry moe curly/]
                                    }
                                    elsif ($type eq 'places') {
                                        return [qw/here there everywhere/],
                                    }
                                }
                                return [];
                            },
        
            # undef means we don't know how to complete the value: any value specified will do
            # this will result in no shell ompletions, but will still expect a value to be entered
            'name=s'  => undef,

            # boolean values never have a completion list, and will yell if you are that foolish
            # this will give you --no-fast for free as well
            'fast!'     => undef,

        );

        use Data::Dumper;
        print "The arguments are: " . Dumper(\%ARGS);

DEVELOPMENT
    Patches are welcome.

     http://github.com/sakoht/Getopt--Complete-for-Perl/

     git clone git://github.com/sakoht/Getopt--Complete-for-Perl.git

    As are complaints. Help us find bugs by sending an email to the address
    below, or using CPAN's bug tracking system:

     https://rt.cpan.org/

    The latest version of this module is always availabe on CPAN:

     http://search.cpan.org/search?query=Getopt%3A%3AComplete&mode=all

    And is readily installable with the CPAN shell on Mac, Linux, and other
    Unix-like systems:

     sudo cpan Getopt::Complete

BUGS
    Completions with whitespace work, but they do so by escaping whitespace
    characters instead of quoting. Support should be present for completing
    quoted text. It should also be the default, since it is more attractive.

    The logic to "shorten" the completion options shown in some cases is
    still in development. This means that filename completion shows full
    paths as options instead of just the last word in the file path.

    Some uses of Getopt::Long will not work currently: multi-name options
    (though standard shortening works), +, :, %.

    Currently this module only supports bash, though other shells could be
    added easily.

    There is logic in development to have the tool possibly auto-update the
    user's .bashrc / .bash_profile, but this is incomplete.

SEE ALSO
    Getopt::Complete::Args
        the object API for the option/value argument set

    Getopt::Complete::Options
        the object API for the options specification

    Getopt::Complete::Compgen
        supplies builtin completions like file lists

    Getopt::Long
        the definitive options parser, wrapped by this module

    bash
        the manual page for bash has lots of info on how tab-completion
        works

COPYRIGHT
    Copyright 2009 Scott Smith and Washington University School of Medicine

AUTHORS
    Scott Smith (sakoht at cpan .org)

LICENSE
    This program is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.

    The full text of the license can be found in the LICENSE file included
    with this module.

