NAME
Config::Simple - simple configuration file class
SYNOPSIS
use Config::Simple;
# OO interface:
$cfg = new Config::Simple('app.cfg');
$user = $cfg->param("User"); # read the value
$cfg->param(User=>'sherzodr'); # update
my %Config = $cfg->vars(); # load everything into %Config
$cfg->write(); # saves the changes to file
# tie interface:
tie my %Config, "Config::Simple", "app.cgi";
$user = $Config{'User'};
$Config{'User'} = 'sherzodr';
tied(%Config)->write();
ABSTRACT
Reading and writing configuration files is one of the most frequent
aspects of any software design. Config::Simple is the library to help
you with it.
Config::Simple is a class representing configuration file object. It
supports several configuration file syntax and tries to identify the
file syntax to parse them accordingly. Library supports parsing,
updating and creating configuration files.
ABOUT CONFIGURATION FILES
Keeping configurable variables in your program source code is ugly,
really. And for people without much of a programming experience,
configuring your programs is like performing black magic. Besides, if
you need to access these values from within multiple files, or want your
programs to be able to update configuration files, you just have to
store them in an external file. That's where Config::Simple comes into
play, making it very easy to read and write configuration files.
If you have never used configuration files before, here is a brief
overview of various syntax to choose from.
SIMPLE CONFIGURATION FILE
Simple syntax is what you need for most of your projects. These are, as
the name asserts, the simplest. File consists of key/value pairs,
delimited by nothing but white space. Keys (variables) should be
strictly alpha-numeric with possible dashes (-). Values can hold any
arbitrary text. Here is an example of such a configuration file:
Alias /exec
TempFile /usr/tmp
Comments start with a pound ('#') sign and cannot share the same line
with other configuration data.
HTTP-LIKE SYNTAX
This format of separating key/value pairs is used by HTTP messages. Each
key/value is separated by semi-colon (:). Keys are alphanumeric strings
with possible '-'. Values can be any arbitrary text:
Example:
Alias: /exec
TempFile: /usr/tmp
It is OK to have spaces around ':'. Comments start with '#' and cannot
share the same line with other configuration data.
INI-FILE
These configuration files are more native to Win32 systems. Data is
organized in blocks. Each key/value pair is delimited with an equal (=)
sign. Blocks are declared on their own lines enclosed in '[' and ']':
[BLOCK1]
KEY1=VALUE1
KEY2=VALUE2
[BLOCK2]
KEY1=VALUE1
KEY2=VALUE2
Your Winamp 2.x play list is an example of such a configuration file.
This is the perfect choice if you need to organize your configuration
file into categories:
[site]
url="http://www.handalak.com"
title="Web site of a \"Geek\""
author=sherzodr
[mysql]
dsn="dbi:mysql:db_name;host=handalak.com"
user=sherzodr
password=marley01
SIMPLIFIED INI-FILE
These files are pretty much similar to traditional ini-files, except
they don't have any block declarations. This style is handy if you do
not want any categorization in your configuration file, but still want
to use '=' delimited key/value pairs. While working with such files,
Config::Simple assigns them to a default block, called 'default' by
default :-).
url = "http://www.handalak.com"
Comments can begin with either pound ('#') or semi-colon (';'). Each
comment should reside on its own line
PROGRAMMING STYLE
Most of the programs simply need to be able to read settings from a
configuration file and assign them to a hash. If that's all you need,
you can simply use its import_from() - class method with the name of the
configuration file and a reference to an existing (possibly empty) hash:
Config::Simple->import_from('myconf.cfg', \%Config);
Now your hash %Config holds all the configuration file's key/value
pairs. Keys of a hash are variable names inside your configuration file,
and values are their respective values. If "myconf.cfg" was a
traditional ini-file, keys of the hash consist of block name and
variable delimited with a dot, such as "block.var".
If that's all you need, you can stop right here. Otherwise, read on.
There is much more Config::Simple offers.
READING THE CONFIGURATION FILE
To be able to use more features of the library, you will need to use its
object interface:
$cfg = new Config::Simple('app.cfg');
The above line reads and parses the configuration file accordingly. It
tries to guess which syntax is used by passing the file to
guess_syntax() method. Alternatively, you can create an empty object,
and only then read the configuration file in:
$cfg = new Config::Simple();
$cfg->read('app.cfg');
As in the first example, read() also calls guess_syntax() method on the
file.
If, for any reason, it fails to guess the syntax correctly (which is
less likely), you can try to debug by using its guess_syntax() method.
It expects file handle for a configuration file and returns the name of
a syntax. Return value is one of "ini", "simple" or "http".
open(FH, "app.cfg");
printf("This file uses '%s' syntax\n", $cfg->guess_syntax(\*FH));
ACCESSING VALUES
After you read the configuration file in successfully, you can use
param() method to access the configuration values. For example:
$user = $cfg->param("User");
will return the value of "User" from either simple configuration file,
or http-styled configuration as well as simplified ini-files. To access
the value from a traditional ini-file, consider the following syntax:
$user = $cfg->param("mysql.user");
The above returns the value of "user" from within "[mysql]" block.
Notice the use of dot "." to delimit block and key names.
Config::Simple also supports vars() method, which, depending on the
context used, returns all the values either as hashref or hash:
my %Config = $cfg->vars();
print "Username: $Config{User}";
# If it was a traditional ini-file:
print "Username: $Config{'mysql.user'}";
If you call vars() in scalar context, you will end up with a reference
to a hash:
my $Config = $cfg->vars();
print "Username: $Config->{User}";
If you know what you're doing, you can also have an option of importing
all the names from the configuration file into your current name space
as global variables. All the block/key names will be uppercased and will
be converted to Perl's valid variable names; that is, all the dots
(block-key separator) and other '\W' characters will be substituted with
underscore '_':
$cfg = new Config::Simple('app.cfg');
$cfg->import_names();
# or, with a single line:
Config::Simple->new('app.cfg')->import_names();
print STDERR "Debugging mode is on" if $DEBUG_MODE;
In the above example, if there was a variable 'mode' under '[debug]'
block, it will be now accessible via $DEBUG_MODE, as opposed to
$cfg->param('debug.mode');
"import_names()" by default imports the values to its caller's name
space. Optionally, you can specify where to import the values by passing
the name of the name space as the first argument. It also prevents
potential name collisions:
Config::Simple->new('app.cfg')->import_names('CFG');
print STDERR "Debugging mode is on" if $CFG::DEBUG_MODE;
If all you want is to import values from a configuration file, the above
syntax may still seem longer than necessary. That's why Config::Simple
supports import_from() - class method, which is called with the name of
the configuration file. It will call import_names() for you:
Config::Simple->import_from('app.cfg');
The above line imports all the variables into the caller's name space.
It's similar to calling import_names() on an object. If you pass a
string as the second argument, it will treat it as the alternative name
space to import the names into. As we already showed in the very first
example, you can also pass a reference to an existing hash as the second
argument. In this case, that hash will be modified with the values of
the configuration file.
# import into $CFG name space:
Config::Simple->import_from('app.cfg', 'CFG');
# import into %Config hash:
Config::Simple->import_from('app.cfg', \%Config);
The above line imports all the values to 'CFG' name space. import_from()
returns underlying Config::Simple object (which you may not even need
anymore):
$cfg = Config::Simple->import_from('app.cfg', \my %Config);
$cfg->write('app.cfg.bak');
UPDATING THE VALUES
Configuration values, once read into Config::Simple, can be updated from
within your program by using the same param() method used for accessing
them. For example:
$cfg->param("User", "sherzodR");
The above line changes the value of "User" to "sherzodR". Similar syntax
is applicable for ini-files as well:
$cfg->param("mysql.user", "sherzodR");
If the key you're trying to update does not exist, it will be created.
For example, to add a new "[session]" block to your ini-file, assuming
this block doesn't already exist:
$cfg->param("session.life", "+1M");
You can also delete values calling delete() method with the name of the
variable:
$cfg->delete('mysql.user'); # deletes 'user' under [mysql] block
SAVING/WRITING CONFIGURATION FILES
The above updates to the configuration values are in-memory operations.
They do not reflect in the file itself. To modify the files accordingly,
you need to call either "write()" or "save()" methods on the object:
$cfg->write();
The above line writes the modifications to the configuration file.
Alternatively, you can pass a name to either write() or save() to
indicate the name of the file to create instead of modifying existing
configuration file:
$cfg->write("app.cfg.bak");
If you want the changes saved at all times, you can turn "autosave" mode
on by passing true value to $cfg->autosave(). It will make sure before
your program is terminated, all the configuration values are written
back to its file:
$cfg = new Config::Simple('aff.cfg');
$cfg->autosave(1);
CREATING CONFIGURATION FILES
Occasionally, your programs may want to create their own configuration
files on the fly, possibly from a user input. To create a configuration
file from scratch using Config::Simple, simply create an empty
configuration file object and define your syntax. You can do it by
either passing "syntax" option to new(), or by calling syntax() method.
Then play with param() method as you normally would. When you're done,
call write() method with the name of the configuration file:
$cfg = new Config::Simple(syntax=>'ini');
# or you could also do:
# $cfg->autosave('ini')
$cfg->param("mysql.dsn", "DBI:mysql:db;host=handalak.com");
$cfg->param("mysql.user", "sherzodr");
$cfg->param("mysql.pass", 'marley01');
$cfg->param("site.title", 'sherzodR "The Geek"');
$cfg->write("new.cfg");
This creates the a file "new.cfg" with the following content:
; Config::Simple 4.43
; Sat Mar 8 00:32:49 2003
[site]
title=sherzodR "The Geek"
[mysql]
pass=marley01
dsn=DBI:mysql:db;host=handalak.com
user=sherzodr
Neat, huh? Supported syntax keywords are "ini", "simple" or "http".
Currently there is no support for creating simplified ini-files.
MULTIPLE VALUES
Ever wanted to define array of values in your single configuration
variable? I have! That's why Config::Simple supports this fancy feature
as well. Simply separate your values with a comma:
Files hp.cgi, template.html, styles.css
Now param() method returns an array of values:
@files = $cfg->param("Files");
unlink $_ for @files;
If you want a comma as part of a value, enclose the value(s) in double
quotes:
CVSFiles "hp.cgi,v", "template.html,v", "styles.css,v"
In case you want either of the values to hold literal quote ("), you can
escape it with a backlash:
SiteTitle "sherzod \"The Geek\""
TIE INTERFACE
If OO style intimidates you, Config::Simple also supports tie()
interface. This interface allows you to tie() an ordinary Perl hash to
the configuration file. From that point on, you can use the variable as
an ordinary Perl hash.
tie %Config, "Config::Simple", 'app.cfg';
# Using %Config as an ordinary hash
print "Username is '$Config{User}'\n";
$Config{User} = 'sherzodR';
To access the method provided in OO syntax, you need to get underlying
Config::Simple object. You can do so with tied() function:
tied(%Config)->write();
WARNING: tie interface is experimental and not well tested yet. It also
doesn't perform all the hash manipulating operations of Perl. Let me
know if you encounter a problem.
MISCELLANEOUS
CASE SENSITIVITY
By default, configuration file keys and values are case sensitive. Which
means, $cfg->param("User") and $cfg->param("user") are referring to two
different values. But it is possible to force Config::Simple to ignore
cases all together by enabling "-lc" switch while loading the library:
use Config::Simple ('-lc');
WARNING: If you call write() or save(), while working on "-lc" mode, all
the case information of the original file will be lost. So use it if you
know what you're doing.
USING QUOTES
Some people suggest if values consist of none alpha-numeric strings,
they should be enclosed in double quotes. Well, says them! Although
Config::Simple supports parsing such configuration files already, it
doesn't follow this rule while writing them. If you really need it to
generate such compatible configuration files, "-strict" switch is what
you need:
use Config::Simple '-strict';
Now, when you write the configuration data back to files, if values hold
any none alpha-numeric strings, they will be quoted accordingly. All the
double quotes that are part of the value will be escaped with a
backslash.
EXCEPTION HANDLING
Config::Simple doesn't believe in dying that easily (unless you insult
it using wrong syntax). It leaves the decision to the programmer
implementing the library. You can use its error() - class method to
access underlying error message. Methods that require you to check for
their return values are read() and write(). If you pass filename to
new(), you will need to check its return value as well. They return any
true value indicating success, undef otherwise:
# following new always returns true:
$cfg = new Config::Simple();
# read() can fail:
$cfg->read('app.cfg') or die $cfg->error();
# following new() can fail:
$cfg = new Config::Simple('app.cfg') or die Config::Simple->error();
# import_from() calls read(), so it can fail:
Config::Simple->import_from('app.cfg', \%Config) or die Config::Simple->error();
# write() may fail:
$cfg->write() or die $cfg->error();
METHODS
new()
- constructor. Optionally accepts several arguments. Returns
Config::Simple object. Supported arguments are filename, syntax,
autosave. If there is a single argument, will be treated as the name
of the configuration.
read()
- accepts name of the configuration file to parse. Before that, it
tries to guess the syntax of the file by calling guess_syntax()
method. Then calls either of parse_ini_file(), parse_cfg_file() or
parse_http_file() accordingly. If the name of the file is provided
to the constructor - new(), there is no need to call read().
param([$name], [$value])
- used for accessing and updating configuration variables. If used
with no arguments returns all the available names from the
configuration file.
delete($name)
- deletes a variable from a configuration file. $name has the same
meaning and syntax as it does in param()
vars()
- depending on the context used, returns all the values available in
the configuration file either as a hash or a reference to a hash
import_names()
- imports all the names from the configuration file to the caller's
name space. Optional argument, if passed, will be treated as the
name space variables to be imported into. All the names will be
uppercased. Non-alphanumeric strings in the values will be
underscored
import_from()
- class method. Accepts the name of the file to import names from.
Additional arguments will be passed to import_names(). Returns
underlying Config::Simple object
get_block($name)
is mostly used for accessing blocks in ini-styled configuration
files. Returns a hashref of all the key/value pairs of a given
block. Also supported by param() method with the help of "-block"
option:
$hash = $cfg->get_block('Project');
# is the same as saying:
$hash = $cfg->param(-block=>'Project');
set_block($name, $values)
used in assigning contents to a block in ini-styled configuration
files. $name should be the name of a [block], and $values is assumed
to be a hashref mapping key/value pairs. Also supported by param()
method with the help of "-block" and "-value" (or "-values")
options:
$cfg->set_block('Project', {Count=>3, 'Multiple Column' => 20});
# is the same as:
$cfg->param(-block=>'Project', -value=>{Count=>3, 'Multiple Column' => 20});
Warning: all the contents of a block, if previously existed will be
wiped out. If you want to set specific key/value pairs, use explicit
method:
$cfg->param('Project.Count', 3);
as_string()
- returns the configuration file as a chunk of text. It is the same
text used by write() and save() to store the new configuration file
back to file.
write()
- writes the configuration file into disk. Argument, if passed, will
be treated as the name of the file configuration variables should be
saved in.
save()
- same as write().
dump()
- for debugging only. Dumps the whole Config::Simple object using
Data::Dumper. Argument, if passed, will be treated as the name of
the file object should be dumped in. The second argument specifies
amount of indentation as documented in Data::Dumper manual. Default
indent size is 2.
error()
- returns the last error message from read/write or import_*
operations.
TODO
* Support for lines with continuation character, '\'.
* Retaining comments while writing the configuration files back and/or
methods for manipulating comments. Everyone loves comments!
* Support for Apache-like style configuration file. For now, if you
want this functionality, checkout the Config::General manpage
instead.
BUGS
Submit bugs to Sherzod B. Ruzmetov <sherzodr@cpan.org>
CREDITS
Michael Caldwell (mjc@mjcnet.com)
whitespace support, "-lc" switch and for various bug fixes
Scott Weinstein (Scott.Weinstein@lazard.com)
bug fix in TIEHASH
Ruslan U. Zakirov <cubic@wr.miee.ru>
default name space suggestion and patch
Hirosi Taguti
import_names() and import_from() idea.
COPYRIGHT
Copyright (C) 2002-2003 Sherzod B. Ruzmetov.
This software is free library. You can modify and/or distribute it
under the same terms as Perl itself
AUTHOR
Sherzod B. Ruzmetov E<lt>sherzodr@cpan.orgE<gt>
URI: http://author.handalak.com
SEE ALSO
the Config::General manpage, the Config::Simple manpage, the
Config::Tiny manpage