AppConfig(3pm) User Contributed Perl Documentation AppConfig(3pm)
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 initialized 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.
$config->define("foo", "bar" => { ALIAS = "boozer" }, "baz");
See AppConfig::State for full details of the configuration options
available when defining variables. These are, in brief:
DEFAULT
The default value for the variable (default: undef).
ALIAS
One or more (list reference or "list|like|this") alternative names
for the variable.
ARGCOUNT
Specifies the number and type of arguments that the variable
expects. Constants in ":argcount" tag set define ARGCOUNT_NONE -
simple on/off flag (default), ARGCOUNT_ONE - single value,
ARGCOUNT_LIST - multiple values accessed via list reference,
ARGCOUNT_HASH - hash table, "key=value", accessed via hash
reference.
ARGS
Used to provide an argument specification string to pass to
Getopt::Long via AppConfig::Getopt. E.g. "=i", ":s", "=s@". This
can also be used to implicitly set the ARGCOUNT value ("/^!/" =
ARGCOUNT_NONE, "/@/" = ARGCOUNT_LIST, "/%/" = ARGCOUNT_HASH,
"/[=:].*/" = ARGCOUNT_ONE)
EXPAND
Specifies which variable expansion policies should be used when
parsing configuration files. Constants in ":expand" tag set
define:
EXPAND_NONE - no expansion (default)
EXPAND_VAR - expand C<$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 validation
(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 compact 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 = $config->drink();
print join(", ", @$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 successive 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 initializes 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
writable 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 subsequently 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.
REPOSITORY
<https://github.com/neilbowers/AppConfig>
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).
COPYRIGHT
Copyright (C) 1997-2007 Andy Wardley. All Rights Reserved.
Copyright (C) 1997,1998 Canon Research Centre Europe Ltd.
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
perl v5.36.0 2023-05-28 AppConfig(3pm)
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