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.
$config->define("foo", "bar" => { ALIAS = "boozer" }, "baz");
See AppConfig::State for full details of the configuration options available
when defining variables. These are, in brief:
- DEFAULT
- The default value for the variable (default: undef).
- ALIAS
- One or more (list reference or "list|like|this") alternative
names for the variable.
- ARGCOUNT
- Specifies the number and type of arguments that the variable expects.
Constants in ":argcount" tag set define ARGCOUNT_NONE - simple
on/off flag (default), ARGCOUNT_ONE - single value, ARGCOUNT_LIST -
multiple values accessed via list reference, ARGCOUNT_HASH - hash table,
"key=value", accessed via hash reference.
- ARGS
- Used to provide an argument specification string to pass to Getopt::Long
via AppConfig::Getopt. E.g. "=i", ":s",
"=s@". This can also be used to implicitly set the ARGCOUNT
value ("/^!/" = ARGCOUNT_NONE, "/@/" = ARGCOUNT_LIST,
"/%/" = ARGCOUNT_HASH, "/[=:].*/" = ARGCOUNT_ONE)
- EXPAND
- Specifies which variable expansion policies should be used when parsing
configuration files. Constants in ":expand" tag set define:
EXPAND_NONE - no expansion (default)
EXPAND_VAR - expand C<$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 validaton (variable may now be
set).
- ACTION
- Code reference to be called whenever variable value changes.
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).
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