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Simple(3pm) User Contributed Perl Documentation Simple(3pm)
NAME
Config::Simple - simple configuration file class
SYNOPSIS
use Config::Simple;
# --- Simple usage. Loads the config. file into a hash:
Config::Simple->import_from('app.ini', \%Config);
# --- OO interface:
$cfg = new Config::Simple('app.ini');
# accessing values:
$user = $cfg->param('User');
# getting the values as a hash:
%Config = $cfg->vars();
# updating value with a string
$cfg->param('User', 'sherzodR');
# updating a value with an array:
$cfg->param('Users', ['sherzodR', 'geek', 'merlyn']);
# adding a new block to an ini-file:
$cfg->param(-block=>'last-access', -values=>{'time'=>time()});
# accessing a block of an ini-file;
$mysql = $cfg->param(-block=>'mysql');
# saving the changes back to file:
$cfg->save();
# --- tie() interface
tie %Config, "Config::Simple", 'app.ini';
ABSTRACT
Reading and writing configuration files is one of the most frequent tasks of any software
design. Config::Simple is the library that helps 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 automatically. 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, want your programs to be able to update configuration files or want to provide a
friendlier user interface for your 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. Otherwise you can jump to "PROGRAMMING STYLE".
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 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 $_ for @files;
If you want a comma as part of a value, enclose the value(s) in double quotes:
CVSFiles "hp.cgi,v", "template.html,v", "styles.css,v"
In case you want either of the values to hold literal quote ("), you can escape it with a
backlash:
SiteTitle "sherzod \"The Geek\""
TIE INTERFACE
If OO style intimidates you, and "import_from()" is too simple for you, Config::Simple
also supports tie() interface. This interface allows you to tie() an ordinary Perl hash to
the configuration file. From that point on, you can use the variable as an ordinary Perl
hash.
tie %Config, "Config::Simple", 'app.cfg';
# Using %Config as an ordinary hash
print "Username is '$Config{User}'\n";
$Config{User} = 'sherzodR';
The difference between "import_from($file, \%Hash)" is, all the changes you make to the
hash after tie()ing it, will also reflect in the configuration file object. If autosave()
was turned on, they will also be written back to file:
tie %Config, "Config::Simple", "app.cfg";
tied(%Config)->autosave(1);
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. 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 $cfg->error();
# tie() may fail, since it calls new() with a filename
tie %Config, "Config::Simple", 'app.cfg' or die Config::Simple->error();
METHODS
new()
- constructor. Optionally accepts several arguments. Returns Config::Simple object.
Supported arguments are filename, syntax, autosave. If there is a single argument,
will be treated as the name of the configuration file.
autosave([$bool])
- turns 'autosave' mode on if passed true argument. Returns current autosave mode if
used without arguments. In 'autosave' mode Config::Simple writes all the changes back
to its file without you having to call write() or save()
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. $name has the same meaning and syntax
as it does in param($name)
clear()
- clears all the data from the object. Calling save() or turning autosave() on results
in an empty configuration file as well.
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([$NS])
- imports all the names from the configuration file to the caller's name space.
Optional argument, if passed, will be treated as the name space variables to be
imported into. All the names will be uppercased. Non-alphanumeric strings in the
values will be underscored
import_from($file, \%hash | $NS)
- class method. If the second argument is a reference to an existing hash, it will
load all the configuration contents into that hash. If the second argument is a
string, it will be treated as the name space variables should be imported into, just
like import_names() does.
get_block($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
o Support for lines with continuation character, '\'. Currently its support is
restricted and quite possibly buggy.
o Retaining comments while writing the configuration files back and/or methods for
manipulating comments. Everyone loves comments!
o Retain the order of the blocks and other variables in the configuration files.
BUGS
Submit bugs and possibly patches to Sherzod B. Ruzmetov <sherzodr AT cpan.org>.
CREDITS
Michael Caldwell (mjc AT mjcnet.com)
whitespace support, "-lc" switch and for various bug fixes
Scott Weinstein (Scott.Weinstein AT lazard.com)
bug fix in TIEHASH
Ruslan U. Zakirov <cubic AT wr.ru>
default name space suggestion and patch
Hirosi Taguti
import_names() and import_from() idea.
Vitaly Kushneriuk
for bug fixes and suggestions
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 AT cpan.orgE<gt>
URI: http://author.handalak.com
SEE ALSO
Config::General, Config::Simple, Config::Tiny
perl v5.32.0 2020-12-28 Simple(3pm)
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On Apache
Under GNU General Public License
2025-11-21 17:25 @216.73.216.164 CrawledBy Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)