Config::Simple - simple configuration file class
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';
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.
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 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.
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.
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
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
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.
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));
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');
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
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);
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.
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 $_ for @files;
If you want a comma as part of a value, enclose the value(s) in double quotes:
CVSFiles "hp.cgi,v", "template.html,v", "styles.css,v"
In case you want either of the values to hold literal quote ("), you can
escape it with a backlash:
SiteTitle "sherzod \"The Geek\""
If OO style intimidates you, and "import_from()" is too simple for
you, Config::Simple also supports
tie() interface. This interface
allows you to
tie() an ordinary Perl hash to the configuration file.
From that point on, you can use the variable as an ordinary Perl hash.
tie %Config, "Config::Simple", 'app.cfg';
# Using %Config as an ordinary hash
print "Username is '$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.
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.
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.
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 $cfg->error();
# tie() may fail, since it calls new() with a filename
tie %Config, "Config::Simple", 'app.cfg' or die Config::Simple->error();
- new()
- - constructor. Optionally accepts several arguments.
Returns Config::Simple object. Supported arguments are filename,
syntax, autosave. If there is a single argument, will be
treated as the name of the configuration file.
- autosave([$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.
- •
- Support for lines with continuation character, '\'.
Currently its support is restricted and quite possibly buggy.
- •
- Retaining comments while writing the configuration files
back and/or methods for manipulating comments. Everyone loves
comments!
- •
- Retain the order of the blocks and other variables in the
configuration files.
Submit bugs and possibly patches to Sherzod B. Ruzmetov
<
[email protected]>.
- Michael Caldwell ([email protected])
- whitespace support, "-lc" switch and for various
bug fixes
- Scott Weinstein ([email protected])
- bug fix in TIEHASH
- Ruslan U. Zakirov <[email protected]>
- default name space suggestion and patch
- Hirosi Taguti
-
import_names() and import_from() idea.
- Vitaly Kushneriuk
- for bug fixes and suggestions
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
Sherzod B. Ruzmetov E<lt>[email protected]<gt>
URI: http://author.handalak.com
Config::General, Config::Simple, Config::Tiny