strict_config 1.0.1

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Configuration parser with error checking, validation and logging config support.

Package for extracting values from a config.

Features #

  • Built-in validation for error checking:

    • Detects missing mandatory items.
    • Optional scalar values can be assigned default values.
    • Maximum and/or minimum limits can be specified for integer values.
    • Permitted strings can be specified to restrict possible string values.
    • Leading and trailing whitespace in strings removed by default.
    • Multiple whitespace in strings replaced with a single space by default.
    • Empty and blank strings rejected by default.
    • Empty list values are accepted by default. Defaults can be changed.
    • Unexpected items in the config can be detected.
  • Configs can contain logger levels for use with the Dart logging package.

  • Does not use Dart annotations, so programs can be compiled with dart2native.

Example #

Example config:

name: "Example"
description: "An example config"

server:
  host: "localhost"
  port: 8080
  tls: true

Program to read the example config:

import 'dart:io';
import 'package:strict_config/strict_config.dart';

class ExampleConfig {
  ExampleConfig(ConfigMap m) {
    name = m.string('name');
    desc = m.stringOptional('description', keepWhitespace: true);
    server = ServerConfig(m.map('server'));
    m.unusedKeysCheck();
  }

  String name;
  String desc;
  ServerConfig server;
}

class ServerConfig {
  ServerConfig(ConfigMap m) {
    host = m.string('host');
    tls = m.boolean('tls', defaultValue: true);
    port = m.integer('port', min: 1, max: 65535, defaultValue: tls ? 443 : 80);
    m.unusedKeysCheck();
  }

  String host;
  bool tls;
  int port;
}

void main(List<String> args) {
  final filename = args.isNotEmpty ? args.first : 'example.conf';

  try {
    final text = File(filename).readAsStringSync();

    final config = ExampleConfig(ConfigMap(text));

    print('Name: ${config.name}');
    if (config.desc != null) {
      print('Description: ${config.desc}');
    }
    print('Host: ${config.server.host}');
    print('TLS: ${config.server.tls}');
    print('Port: ${config.server.port}');

    exit(0);
  } on ConfigException catch (e) {
    stderr.write('Error: $filename: $e\n');
    exit(1);
  } on FileSystemException catch (e) {
    stderr.write('Error: ${e.path}: ${e.message}\n');
    exit(1);
  }
}

Usage #

Create a ConfigMap from the text representation of a config. The text is usually from a config file.

Extract expected values from config maps using the extraction methods.

  • For mandatory scalar values, use boolean, integer and string.
  • For optional scalar values, use booleanOptional, integerOptional and stringOptional.
  • For values which are config maps, use map or mapOptional.
  • For values which are lists use booleans, integers, strings and maps.
  • If the list is optional, use booleansOptional, integersOptional, stringsOptional and mapsOptional.

Use unusedKeysCheck to check a config map for unexpected keys.

See the API reference for details.

Configs #

Data model #

A config is a config map at the top-level.

A config map is an unordered collection of zero or more key-value pairs.

The keys are case-sensitive strings. Within the context of each config map, the keys must be unique.

The values must be one of these types:

  • boolean: true or false
  • integers
  • strings: optionally enclosed in double quotes
  • config maps
  • list of booleans
  • list of integers
  • list of strings
  • list of config maps

Syntax #

A subset of YAML is used as the syntax of a config.

Features and bugs #

Please file feature requests and bugs at the issue tracker.

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Publisher

hoylen.com

Configuration parser with error checking, validation and logging config support.

Repository (GitHub)
View/report issues

Documentation

API reference

License

BSD (LICENSE)

Dependencies

logging, yaml

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