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AppConfig - Perl5 module for reading configuration files and parsing command line arguments. |
AppConfig - Perl5 module for reading configuration files and parsing command line arguments.
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(\@ARGV);
# advanced command line options with Getopt::Long
$config->getopt(\@ARGV);
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 and command line arguments.
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 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
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 requires Perl 5.004 or later.
The AppConfig::Getopt module uses Getopt::Long for advanced command-line option processing and requires version 2.17 or later. There is also a simple internal module (AppConfig::Args) for command line parsing that does not have the flexibility of AppConfig::Getopt but is smaller and incurs less overhead. The Getopt::Long module is not required when this is used. The Makefile.PL specifies Getopt::Long version 2.17 as a pre-requisite. If you wish to use AppConfig without Getopt::Long then comment out the following line in the Makefile.PL:
# 'PREREQ_PM' => { 'Getopt::Long' => 2.17 },
No action is necessary if you already have Getopt::Long 2.17 or later installed. Getopt::Long is available from any CPAN site (see below).
All AppConfig::* and other modules (e.g. Getopt::Long) are dynamically loaded by the AppConfig module as and when required.
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 Revision number, of the form ``2.00''. 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.
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 the AppConfig::State manpage for full details of the configuration options available. These are, in brief:
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);
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 eqivalent 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 the AppConfig::State manpage) for full details of the configuration options available when defining variables. These are, in brief:
: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.
/^!/ = ARGCOUNT_NONE, /@/ =
ARGCOUNT_LIST, /%/ = ARGCOUNT_HASH, /[=:].*/ = ARGCOUNT_ONE)
:argcount tag set define EXPAND_NONE
- no expansion (default), EXPAND_VAR - expand $var or $(var) as
other AppConfig variables, EXPAND_UID - expand ~uid as user's home
directory, EXPAND_ENV - expand ${var} as environment variable,
EXPAND_ALL - do all expansions. May be logically or'd.
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|aliasE<lt>argopts<gt>"
The first element indicates the variable name and subsequent ALIAS values may be added, each separated by a vertical bar '|'.
The <argopts<gt> element indicates the ARGCOUNT value and may be one of the following;
! ARGCOUNT_NONE
=s ARGCOUNT_ONE
=s@ ARGCOUNT_LIST
=s% ARGCOUNT_HASH
The ``=s'' element
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 => "f",
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.
$config->define("file|filelist|f=s@", { VALIDATE = \&check_file() } );
AppConfig defines two methods (via AppConfig::State) to manipulate variable values
set($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"
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(s). 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. An 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 h="history"
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, environment variable and tilde (home directory) expansions 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 the AppConfig::State manpage 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
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 (unless) 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 the remaining 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 the AppConfig::Args manpage 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 configuartion 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.
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_NONE
EXPAND_VAR
EXPAND_UID
EXPAND_ENV
EXPAND_ALL # EXPAND_VARS | EXPAND_UIDS | EXPAND_ENVS
EXPAND_WARN
See AppConfig::File for full details of the use of these constants.
ARGCOUNT_NONE
ARGCOUNT_ONE
ARGCOUNT_LIST
ARGCOUNT_HASH
See AppConfig::State for full details of the use of these constants.
Andy Wardley, <abw@cre.canon.co.uk>, http://www.kfs.org/~abw/
Web Technology Group, Canon Research Centre Europe Ltd.
$Revision: 1.52 $
Copyright (C) 1998 Canon Research Centre Europe Ltd. All Rights Reserved.
This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
AppConfig::State, AppConfig::File, AppConfig::Args, AppConfig::Getopt, Getopt::Long
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AppConfig - Perl5 module for reading configuration files and parsing command line arguments. |