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NAME
    AppConfig - Perl5 module for reading configuration files and parsing
    command line arguments.

SYNOPSIS
        use AppConfig;
    
        # create a new AppConfig object
        my $config = AppConfig->new( \%cfg );
    
        # define a new variable
        $config->define( $varname => \%varopts );
    
        # create/define combined
        my $config = AppConfig->new( \%cfg, 
            $varname => \%varopts,
            $varname => \%varopts,
            ...
        );
    
        # set/get the value
        $config->set( $varname, $value );
        $config->get($varname);
    
        # shortcut form
        $config->varname($value);
        $config->varname;
    
        # read configuration file
        $config->file($file);
    
        # parse command line options
        $config->args(\@args);      # default to \@ARGV
    
        # advanced command line options with Getopt::Long
        $config->getopt(\@args);    # default to \@ARGV
    
        # parse CGI parameters (GET method)
        $config->cgi($query);       # default to $ENV{ QUERY_STRING }

OVERVIEW
    AppConfig is a Perl5 module for managing application configuration
    information. It maintains the state of any number of variables and
    provides methods for parsing configuration files, command line arguments
    and CGI script parameters.

Variables values may be set via configuration files. Variables may be
    flags (On/Off), take a single value, or take multiple values stored as a
    list or hash. The number of arguments a variable expects is determined
    by its configuration when defined.

# flags
        verbose 
        nohelp
        debug = On
    
        # single value
        home  = /home/abw/
    
        # multiple list value
        file = /tmp/file1
        file = /tmp/file2
    
        # multiple hash value
        book  camel = Programming Perl
        book  llama = Learning Perl

The '-' prefix can be used to reset a variable to its default value and
    the '+' prefix can be used to set it to 1

-verbose
        +debug

Variable, environment variable and tilde (home directory) expansions can
    be applied (selectively, if necessary) to the values read from
    configuration files:

home = ~                    # home directory
        nntp = ${NNTPSERVER}        # environment variable
        html = $home/html           # internal variables
        img  = $html/images

Configuration files may be arranged in blocks as per the style of Win32
    "INI" files.

[file]
        site = kfs
        src  = ~/websrc/docs/$site
        lib  = ~/websrc/lib
        dest = ~/public_html/$site
    
        [page]
        header = $lib/header
        footer = $lib/footer

You can also use Perl's "heredoc" syntax to define a large block of text
    in a configuration file.

multiline = <<FOOBAR
        line 1
        line 2
        FOOBAR
    
        paths  exe  = "${PATH}:${HOME}/.bin"
        paths  link = <<'FOO'
        ${LD_LIBARRAY_PATH}:${HOME}/lib
        FOO

Variables may also be set by parsing command line arguments.

myapp -verbose -site kfs -file f1 -file f2

AppConfig provides a simple method (args()) for parsing command line
    arguments. A second method (getopt()) allows more complex argument
    processing by delegation to Johan Vroman's Getopt::Long module.

AppConfig also allows variables to be set by parameters passed to a CGI
    script via the URL (GET method).

http://www.nowhere.com/cgi-bin/myapp?verbose&site=kfs

PREREQUISITES
    AppConfig requires Perl 5.005 or later.

The Getopt::Long and Test::More modules should be installed. If you are
    using a recent version of Perl (e.g. 5.8.0) then these should already be
    installed.

OBTAINING AND INSTALLING THE AppConfig MODULE BUNDLE
    The AppConfig module bundle is available from CPAN. As the 'perlmod'
    manual page explains:

CPAN stands for the Comprehensive Perl Archive Network.
        This is a globally replicated collection of all known Perl
        materials, including hundreds of unbundled modules.  
    
        [...]
    
        For an up-to-date listing of CPAN sites, see
        http://www.perl.com/perl/ or ftp://ftp.perl.com/perl/ .

Within the CPAN archive, AppConfig is in the category:

12) Option, Argument, Parameter and Configuration File Processing

The module is available in the following directories:

/modules/by-module/AppConfig/AppConfig-<version>.tar.gz
        /authors/id/ABW/AppConfig-<version>.tar.gz

AppConfig is distributed as a single gzipped tar archive file:

AppConfig-<version>.tar.gz

Note that "<version>" represents the current AppConfig version number,
    of the form "n.nn", e.g. "3.14". See the REVISION section below to
    determine the current version number for AppConfig.

Unpack the archive to create a AppConfig installation directory:

gunzip AppConfig-<version>.tar.gz
        tar xvf AppConfig-<version>.tar

'cd' into that directory, make, test and install the modules:

cd AppConfig-<version>
        perl Makefile.PL
        make
        make test
        make install

The 't' sub-directory contains a number of test scripts that are run
    when a 'make test' is run.

The 'make install' will install the module on your system. You may need
    administrator privileges to perform this task. If you install the module
    in a local directory (for example, by executing "perl Makefile.PL
    LIB=~/lib" in the above - see "perldoc MakeMaker" for full details), you
    will need to ensure that the PERL5LIB environment variable is set to
    include the location, or add a line to your scripts explicitly naming
    the library location:

use lib '/local/path/to/lib';

The 'examples' sub-directory contains some simple examples of using the
    AppConfig modules.

DESCRIPTION
  USING THE AppConfig MODULE
    To import and use the AppConfig module the following line should appear
    in your Perl script:

use AppConfig;

To import constants defined by the AppConfig module, specify the name of
    one or more of the constant or tag sets as parameters to "use":

use AppConfig qw(:expand :argcount);

See "CONSTANT DEFINITIONS" below for more information on the constant
    tagsets defined by AppConfig.

AppConfig is implemented using object-oriented methods. A new AppConfig
    object is created and initialised using the new() method. This returns a
    reference to a new AppConfig object.

my $config = AppConfig->new();

This will create and return a reference to a new AppConfig object.

In doing so, the AppConfig object also creates an internal reference to
    an AppConfig::State object in which to store variable state. All
    arguments passed into the AppConfig constructor are passed directly to
    the AppConfig::State constructor.

The first (optional) parameter may be a reference to a hash array
    containing configuration information.

my $config = AppConfig->new( {
                CASE   => 1,
                ERROR  => \&my_error,
                GLOBAL => { 
                        DEFAULT  => "<unset>", 
                        ARGCOUNT => ARGCOUNT_ONE,
                    },
            } );

See AppConfig::State for full details of the configuration options
    available. These are, in brief:

CASE
        Used to set case sensitivity for variable names (default: off).

CREATE
        Used to indicate that undefined variables should be created
        automatically (default: off).

GLOBAL
        Reference to a hash array of global values used by default when
        defining variables. Valid global values are DEFAULT, ARGCOUNT,
        EXPAND, VALIDATE and ACTION.

PEDANTIC
        Used to indicate that command line and configuration file parsing
        routines should return immediately on encountering an error.

ERROR
        Used to provide a error handling routine. Arguments as per printf().

Subsequent parameters may be variable definitions. These are passed to
    the define() method, described below in "DEFINING VARIABLES".

my $config = AppConfig->new("foo", "bar", "baz");
        my $config = AppConfig->new( { CASE => 1 }, qw(foo bar baz) );

Note that any unresolved method calls to AppConfig are automatically
    delegated to the AppConfig::State object. In practice, it means that it
    is possible to treat the AppConfig object as if it were an
    AppConfig::State object:

# create AppConfig
        my $config = AppConfig->new('foo', 'bar');
    
        # methods get passed through to internal AppConfig::State
        $config->foo(100);
        $config->set('bar', 200);
        $config->define('baz');
        $config->baz(300);

DEFINING VARIABLES
    The "define()" method (delegated to AppConfig::State) is used to
    pre-declare a variable and specify its configuration.

$config->define("foo");

Variables may also be defined directly from the AppConfig new()
    constructor.

my $config = AppConfig->new("foo");

In both simple examples above, a new variable called "foo" is defined. A
    reference to a hash array may also be passed to specify configuration
    information for the variable:

$config->define("foo", {
                DEFAULT   => 99,
                ALIAS     => 'metavar1',
            });

Configuration items specified in the GLOBAL option to the module
    constructor are applied by default when variables are created. e.g.

my $config = AppConfig->new( { 
            GLOBAL => {
                DEFAULT  => "<undef>",
                ARGCOUNT => ARGCOUNT_ONE,
            }
        } );
    
        $config->define("foo");
        $config->define("bar", { ARGCOUNT => ARGCOUNT_NONE } );

is equivalent to:

my $config = AppConfig->new();
    
        $config->define( "foo", {
            DEFAULT  => "<undef>",
            ARGCOUNT => ARGCOUNT_ONE,
        } );
    
        $config->define( "bar", 
            DEFAULT  => "<undef>",
            ARGCOUNT => ARGCOUNT_NONE,
        } );

Multiple variables may be defined in the same call to define().
    Configuration hashes for variables can be omitted.

$config->define("foo", "bar" => { ALIAS = "boozer" }, "baz");

See AppConfig::State for full details of the configuration options
    available when defining variables. These are, in brief:

DEFAULT
        The default value for the variable (default: undef).

ALIAS
        One or more (list reference or "list|like|this") alternative names
        for the variable.

ARGCOUNT
        Specifies the number and type of arguments that the variable
        expects. Constants in ":expand" tag set define ARGCOUNT_NONE -
        simple on/off flag (default), ARGCOUNT_ONE - single value,
        ARGCOUNT_LIST - multiple values accessed via list reference,
        ARGCOUNT_HASH - hash table, "key=value", accessed via hash
        reference.

ARGS
        Used to provide an argument specification string to pass to
        Getopt::Long via AppConfig::Getopt. E.g. "=i", ":s", "=s@". This can
        also be used to implicitly set the ARGCOUNT value ("/^!/" =
        ARGCOUNT_NONE, "/@/" = ARGCOUNT_LIST, "/%/" = ARGCOUNT_HASH,
        "/[=:].*/" = ARGCOUNT_ONE)

EXPAND
        Specifies which variable expansion policies should be used when
        parsing configuration files. Constants in ":expand" tag set define:

EXPAND_NONE - no expansion (default) 
            EXPAND_VAR  - expand C<$var> or C<$(var)> as other variables
            EXPAND_UID  - expand C<~> and C<~uid> as user's home directory 
            EXPAND_ENV - expand C<${var}> as environment variable
            EXPAND_ALL - do all expansions.

VALIDATE
        Regex which the intended variable value should match or code
        reference which returns 1 to indicate successful validaton (variable
        may now be set).

ACTION
        Code reference to be called whenever variable value changes.

COMPACT FORMAT DEFINITION
    Variables can be specified using a compact format. This is identical to
    the specification format of Getopt::Long and is of the form:

"name|alias|alias<argopts>"

The first element indicates the variable name and subsequent ALIAS
    values may be added, each separated by a vertical bar '|'.

The <argopts> element indicates the ARGCOUNT value and may be one of the
    following;

!                  ARGCOUNT_NONE
        =s                 ARGCOUNT_ONE
        =s@                ARGCOUNT_LIST
        =s%                ARGCOUNT_HASH

Additional constructs supported by Getopt::Long may be specified instead
    of the "=s" element (e.g. "=f"). The entire <argopts> element is stored
    in the ARGS parameter for the variable and is passed intact to
    Getopt::Long when the getopt() method is called.

The following examples demonstrate use of the comapct format, with their
    equivalent full specifications:

$config->define("foo|bar|baz!");
    
        $config->define(
                "foo" => { 
                    ALIAS    => "bar|baz", 
                    ARGCOUNT => ARGCOUNT_NONE,
                });
    
        $config->define("name=s");
    
        $config->define(
                "name" => { 
                    ARGCOUNT => ARGCOUNT_ONE,
                });
    
        $config->define("file|filelist|f=s@");
    
        $config->define(
                "file" => { 
                    ALIAS    => "filelist|f", 
                    ARGCOUNT => ARGCOUNT_LIST,
                });
    
        $config->define("user|u=s%");
    
        $config->define(
                "user" => { 
                    ALIAS    => "u", 
                    ARGCOUNT => ARGCOUNT_HASH,
                });

Additional configuration options may be specified by hash reference, as
    per normal. The compact definition format will override any
    configuration values provided for ARGS and ARGCOUNT.

$config->define("file|filelist|f=s@", { VALIDATE = \&check_file() } );

READING AND MODIFYING VARIABLE VALUES
    AppConfig defines two methods (via AppConfig::State) to manipulate
    variable values

set($variable, $value);
        get($variable);

Once defined, variables may be accessed directly as object methods where
    the method name is the same as the variable name. i.e.

$config->set("verbose", 1);

is equivalent to

$config->verbose(1);

Note that AppConfig defines the following methods:

new();
        file();
        args();
        getopt();

And also, through delegation to AppConfig::State:

define()
        get()
        set()
        varlist()

If you define a variable with one of the above names, you will not be
    able to access it directly as an object method. i.e.

$config->file();

This will call the file() method, instead of returning the value of the
    'file' variable. You can work around this by explicitly calling get()
    and set() on a variable whose name conflicts:

$config->get('file');

or by defining a "safe" alias by which the variable can be accessed:

$config->define("file", { ALIAS => "fileopt" });
    or
        $config->define("file|fileopt");

...
        $config->fileopt();

Without parameters, the current value of the variable is returned. If a
    parameter is specified, the variable is set to that value and the result
    of the set() operation is returned.

$config->age(29);        # sets 'age' to 29, returns 1 (ok)
        print $config->age();    # prints "29"

The varlist() method can be used to extract a number of variables into a
    hash array. The first parameter should be a regular expression used for
    matching against the variable names.

my %vars = $config->varlist("^file");   # all "file*" variables

A second parameter may be specified (any true value) to indicate that
    the part of the variable name matching the regex should be removed when
    copied to the target hash.

$config->file_name("/tmp/file");
        $config->file_path("/foo:/bar:/baz");

my %vars = $config->varlist("^file_", 1);

# %vars:
        #    name => /tmp/file
        #    path => "/foo:/bar:/baz"

READING CONFIGURATION FILES
    The AppConfig module provides a streamlined interface for reading
    configuration files with the AppConfig::File module. The file() method
    automatically loads the AppConfig::File module and creates an object to
    process the configuration file or files. Variables stored in the
    internal AppConfig::State are automatically updated with values
    specified in the configuration file.

$config->file($filename);

Multiple files may be passed to file() and should indicate the file name
    or be a reference to an open file handle or glob.

$config->file($filename, $filehandle, \*STDIN, ...);

The file may contain blank lines and comments (prefixed by '#') which
    are ignored. Continutation lines may be marked by ending the line with a
    '\'.

# this is a comment
        callsign = alpha bravo camel delta echo foxtrot golf hipowls \
                   india juliet kilo llama mike november oscar papa  \
                   quebec romeo sierra tango umbrella victor whiskey \
                   x-ray yankee zebra

Variables that are simple flags and do not expect an argument (ARGCOUNT
    = ARGCOUNT_NONE) can be specified without any value. They will be set
    with the value 1, with any value explicitly specified (except "0" and
    "off") being ignored. The variable may also be specified with a "no"
    prefix to implicitly set the variable to 0.

verbose                              # on  (1)
        verbose = 1                          # on  (1)
        verbose = 0                          # off (0)
        verbose off                          # off (0)
        verbose on                           # on  (1)
        verbose mumble                       # on  (1)
        noverbose                            # off (0)

Variables that expect an argument (ARGCOUNT = ARGCOUNT_ONE) will be set
    to whatever follows the variable name, up to the end of the current line
    (including any continuation lines). An optional equals sign may be
    inserted between the variable and value for clarity.

room = /home/kitchen     
        room   /home/bedroom

Each subsequent re-definition of the variable value overwrites the
    previous value.

print $config->room();               # prints "/home/bedroom"

Variables may be defined to accept multiple values (ARGCOUNT =
    ARGCOUNT_LIST). Each subsequent definition of the variable adds the
    value to the list of previously set values for the variable.

drink = coffee
        drink = tea

A reference to a list of values is returned when the variable is
    requested.

my $beverages = $config->drinks();
        print join(", ", @$beverages);      # prints "coffee, tea"

Variables may also be defined as hash lists (ARGCOUNT = ARGCOUNT_HASH).
    Each subsequent definition creates a new key and value in the hash
    array.

alias l="ls -CF"
        alias e="emacs"

A reference to the hash is returned when the variable is requested.

my $aliases = $config->alias();
        foreach my $k (keys %$aliases) {
            print "$k => $aliases->{ $k }\n";
        }

The '-' prefix can be used to reset a variable to its default value and
    the '+' prefix can be used to set it to 1

-verbose
        +debug

VARIABLE EXPANSION
    Variable values may contain references to other AppConfig variables,
    environment variables and/or users' home directories. These will be
    expanded depending on the EXPAND value for each variable or the GLOBAL
    EXPAND value.

Three different expansion types may be applied:

bin = ~/bin          # expand '~' to home dir if EXPAND_UID
        tmp = ~abw/tmp       # as above, but home dir for user 'abw'
    
        perl = $bin/perl     # expand value of 'bin' variable if EXPAND_VAR
        ripl = $(bin)/ripl   # as above with explicit parens
    
        home = ${HOME}       # expand HOME environment var if EXPAND_ENV

See AppConfig::State for more information on expanding variable values.

The configuration files may have variables arranged in blocks. A block
    header, consisting of the block name in square brackets, introduces a
    configuration block. The block name and an underscore are then prefixed
    to the names of all variables subsequently referenced in that block. The
    block continues until the next block definition or to the end of the
    current file.

[block1]
        foo = 10             # block1_foo = 10
    
        [block2]
        foo = 20             # block2_foo = 20

PARSING COMMAND LINE OPTIONS
    There are two methods for processing command line options. The first,
    args(), is a small and efficient implementation which offers basic
    functionality. The second, getopt(), offers a more powerful and complete
    facility by delegating the task to Johan Vroman's Getopt::Long module.
    The trade-off between args() and getopt() is essentially one of
    speed/size against flexibility. Use as appropriate. Both implement
    on-demand loading of modules and incur no overhead until used.

The args() method is used to parse simple command line options. It
    automatically loads the AppConfig::Args module and creates an object to
    process the command line arguments. Variables stored in the internal
    AppConfig::State are automatically updated with values specified in the
    arguments.

The method should be passed a reference to a list of arguments to parse.
    The @ARGV array is used if args() is called without parameters.

$config->args(\@myargs);
        $config->args();               # uses @ARGV

Arguments are read and shifted from the array until the first is
    encountered that is not prefixed by '-' or '--'. At that point, the
    method returns 1 to indicate success, leaving any unprocessed arguments
    remaining in the list.

Each argument should be the name or alias of a variable prefixed by '-'
    or '--'. Arguments that are not prefixed as such (and are not an
    additional parameter to a previous argument) will cause a warning to be
    raised. If the PEDANTIC option is set, the method will return 0
    immediately. With PEDANTIC unset (default), the method will continue to
    parse the rest of the arguments, returning 0 when done.

If the variable is a simple flag (ARGCOUNT = ARGCOUNT_NONE) then it is
    set to the value 1. The variable may be prefixed by "no" to set its
    value to 0.

myprog -verbose --debug -notaste     # $config->verbose(1)
                                             # $config->debug(1)
                                             # $config->taste(0)

Variables that expect an additional argument (ARGCOUNT != 0) will be set
    to the value of the argument following it.

myprog -f /tmp/myfile                # $config->file('/tmp/file');

Variables that expect multiple values (ARGCOUNT = ARGCOUNT_LIST or
    ARGCOUNT_HASH) will have sucessive values added each time the option is
    encountered.

myprog -file /tmp/foo -file /tmp/bar # $config->file('/tmp/foo')
                                             # $config->file('/tmp/bar')
    
        # file => [ '/tmp/foo', '/tmp/bar' ]
    
        myprog -door "jim=Jim Morrison" -door "ray=Ray Manzarek"
                                        # $config->door("jim=Jim Morrison");
                                        # $config->door("ray=Ray Manzarek");
    
        # door => { 'jim' => 'Jim Morrison', 'ray' => 'Ray Manzarek' }

See AppConfig::Args for further details on parsing command line
    arguments.

The getopt() method provides a way to use the power and flexibility of
    the Getopt::Long module to parse command line arguments and have the
    internal values of the AppConfig object updates automatically.

The first (non-list reference) parameters may contain a number of
    configuration string to pass to Getopt::Long::Configure. A reference to
    a list of arguments may additionally be passed or @ARGV is used by
    default.

$config->getopt();                       # uses @ARGV
        $config->getopt(\@myargs);
        $config->getopt(qw(auto_abbrev debug));  # uses @ARGV
        $config->getopt(qw(debug), \@myargs);

See Getopt::Long for details of the configuration options available.

The getopt() method constructs a specification string for each internal
    variable and then initialises Getopt::Long with these values. The
    specification string is constructed from the name, any aliases
    (delimited by a vertical bar '|') and the value of the ARGS parameter.

$config->define("foo", {
            ARGS  => "=i",
            ALIAS => "bar|baz",
        });
    
        # Getopt::Long specification: "foo|bar|baz=i"

Errors and warning generated by the Getopt::Long module are trapped and
    handled by the AppConfig error handler. This may be a user-defined
    routine installed with the ERROR configuration option.

Please note that the AppConfig::Getopt interface is still experimental
    and may not be 100% operational. This is almost undoubtedly due to
    problems in AppConfig::Getopt rather than Getopt::Long.

PARSING CGI PARAMETERS
    The cgi() method provides an interface to the AppConfig::CGI module for
    updating variable values based on the parameters appended to the URL for
    a CGI script. This is commonly known as the CGI "GET" method. The CGI
    "POST" method is currently not supported.

Parameter definitions are separated from the CGI script name by a
    question mark and from each other by ampersands. Where variables have
    specific values, these are appended to the variable with an equals sign:

http://www.here.com/cgi-bin/myscript?foo=bar&baz=qux&verbose

# $config->foo('bar');
            # $config->baz('qux');
            # $config->verbose(1);

Certain values specified in a URL must be escaped in the appropriate
    manner (see CGI specifications at http://www.w3c.org/ for full details).
    The AppConfig::CGI module automatically unescapes the CGI query string
    to restore the parameters to their intended values.

http://where.com/mycgi?title=%22The+Wrong+Trousers%22
    
        # $config->title('"The Wrong Trousers"');

Please be considerate of the security implications of providing
    writeable access to script variables via CGI.

http://rebel.alliance.com/cgi-bin/...
            .../send_report?file=%2Fetc%2Fpasswd&email=darth%40empire.com

To avoid any accidental or malicious changing of "private" variables,
    define only the "public" variables before calling the cgi() (or any
    other) method. Further variables can subequently be defined which can
    not be influenced by the CGI parameters.

$config->define('verbose', 'debug')
        $config->cgi();             # can only set verbose and debug

$config->define('email', 'file');
        $config->file($cfgfile);    # can set verbose, debug, email + file

CONSTANT DEFINITIONS
    A number of constants are defined by the AppConfig module. These may be
    accessed directly (e.g. AppConfig::EXPAND_VARS) or by first importing
    them into the caller's package. Constants are imported by specifying
    their names as arguments to "use AppConfig" or by importing a set of
    constants identified by its "tag set" name.

use AppConfig qw(ARGCOUNT_NONE ARGCOUNT_ONE);

use AppConfig qw(:argcount);

The following tag sets are defined:

:expand
        The ':expand' tagset defines the following constants:

EXPAND_NONE
            EXPAND_VAR
            EXPAND_UID 
            EXPAND_ENV
            EXPAND_ALL       # EXPAND_VAR | EXPAND_UID | EXPAND_ENV
            EXPAND_WARN

See AppConfig::File for full details of the use of these constants.

:argcount
        The ':argcount' tagset defines the following constants:

ARGCOUNT_NONE
            ARGCOUNT_ONE
            ARGCOUNT_LIST 
            ARGCOUNT_HASH

See AppConfig::State for full details of the use of these constants.

AUTHOR
    Andy Wardley, <abw@wardley.org>

With contributions from Dave Viner, Ijon Tichy, Axel Gerstmair and many
    others whose names have been lost to the sands of time (reminders
    welcome).

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

SEE ALSO
    AppConfig::State, AppConfig::File, AppConfig::Args, AppConfig::Getopt,
    AppConfig::CGI, Getopt::Long

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