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Config cpan:TYIL last updated on 2020-07-12

Config-3.0.0/

Config

Extensible configuration class for the Raku programming language.

Installation

This module can be installed using zef:

zef install Config

Depending on the type of configuration file you want to work on, you will need a Config::Parser:: module as well. If you just want an easy-to-use configuration object without reading/writing a file, no parser is needed.

Usage

To start off, specify a template of your configuration. Config will check a couple of directories for a configuration file (based on the XDG base directory spec), and will also automatically try to see if there's any configuration specified in environment variables.

To specify a template, pass it as an argument to new.

my $config = Config.new({
    keyOne => Str,
    keyTwo => {
        NestedKey => "default value",
    },
    keyThree => Int,
}, :name<foobar>);

Important to note here is the name attribute which is being set. This name is used to look up configuration files in default locations and the environment. For this particular example, it will check any directory specified in $XDG_CONFIG_DIRS for files matching foobar.* and foobar/config.*. Afterwards, it will check $XDG_CONFIG_HOME for the same files. If these variables are not set, it will just check $HOME/.config for those files.

Additionally, the environment will be checked for $FOOBAR_KEYONE, $FOOBAR_KEYTWO_NESTEDKEY, and $FOOBAR_KEYTHREE. The former two will be cast to Str appropriately, with $FOOBAR_KEYTHREE being cast to an Int. This ensures that the values are of the correct type, even if they're pulled from a shell environment. This also works for IO::Path!

If you're using the Raku Log module, you can set RAKU_LOG_LEVEL to 7 to see which places it actually checks and reads for values.

You can also manually read configuration files or hashes of values.

# Load a simple configuration hash
$config.=read({
    keyOne => 'value',
    keyTwo => {
        NestedKey => 'other value'
    }
});

# Load a configuration files
$config.=read('/etc/config.yaml');

# Load a configuration file with a specific parser
$config.=read('/etc/config', Config::Parser::ini);

Do note the use of .= here. Config returns a new Config object if you change its values, it is an immutable object. The .= operator provided by Raku is a shorthand for $config = $config.read(...).

To read values from the Config object, you can use the get method, or treat it as a Hash.

# Retrieve a value
$config.get('keyOne');

# Same as above, but treating it as a Hash
$config<keyOne>;

# Retrieve a value by nested key
$config.get('keyTwo.NestedKey');

The Config object can also write it's current configuration back to a file. You must specify a particular Config::Parser implementation as well.

# Write out the configuration using the json parser
$config.write($*HOME.add('.config/foobar/config.json', Config::Parser::json);

Available parsers

Because there's so many ways to structure your configuration files, the parsers for these are their own modules. This allows for easy implementing new parsers, or providing a custom parser for your project's configuration file.

The parser will be loaded during runtime, but you have to make sure it is installed yourself.

The following parsers are available:

Writing your own parser

If you want to make your own parser, simply make a new class which extends the Config::Parser class, and implements the read and write methods. The read method must return a Hash. The write method must return a Bool, True when writing was successful, False if not. Throwing Exceptions to indicate the kind of failure is recommended.

Contributing

If you want to contribute to Config, you can do so by mailing your patches to ~tyil/[email protected]. Any questions or other forms of feedback are welcome too!

License

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License version 3, as published by the Free Software Foundation.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.