Add require interface, update docs

README.md

@@ -1,4 +1,4 @@
 # Conf
 [![Build Status](http://ci.merlin.local/api/badges/adan/Conf/status.svg)](http://ci.merlin.local/adan/Conf)
-
+[![Swift 5](https://img.shields.io/badge/Swift-5-orange.svg?style=flat)](https://developer.apple.com/swift/)
 Config made easy

Sources/Conf/Config.swift

@@ -1,17 +1,22 @@
-///  Key-value storage that can be filled from multiple sources
+/// Key-value storage that can be filled from multiple sources
 public final class Config {
+    /// Returns new config
+    /// - Parameter useEnvironment: if `true` fallback to the environment values for missing keys
     public init(useEnvironment: Bool = false) {
         isBackedByEnvironment = useEnvironment
     }
 
+    /// if `true` fallback to the environment values for missing keys
     let isBackedByEnvironment: Bool
     private let environment = Environment()
     private var data = [Key: String]()
 
+    /// Returns value associated with the given `key`
     func value(for key: Key) -> String? {
         return data[key] ?? envValue(for: key)
     }
 
+    /// Asks enviroment about value associated with the given `key`
     func envValue(for key: Key) -> String? {
         guard isBackedByEnvironment,
             key.path.count == 1,
@@ -20,24 +25,47 @@ public final class Config {
         return environment[variable]
     }
 
+    /// Updates `value` for the given `key`
     func set(value: String?, for key: Key) {
         data[key] = value
     }
 
+    /// Returns value associated with the given `key`
     public subscript(_ key: Key) -> String? {
         get { value(for: key) }
         set { set(value: newValue, for: key) }
     }
 
+    /// Returns value associated with the given `key`
     public subscript<Value>(_ key: Key) -> Value? where Value: LosslessStringConvertible {
         get { value(for: key).flatMap(Value.init) }
         set { set(value: newValue?.description, for: key) }
     }
 
+    /// Returns value associated with the given `key` or throws an error
+    /// - Throws: `ConfigurationError.missing`
+    public func require(_ key: Key) throws -> String {
+        guard let value = self[key]
+            else { throw ConfigurationError.missing(key: key) }
+        return value
+    }
+
+    /// Returns value associated with the given `key` or throws an error
+    /// - Throws: `ConfigurationError.missing`
+    public func require<Value>(_ key: Key) throws -> Value where Value: LosslessStringConvertible {
+        guard let value = self[key] as Value?
+            else { throw ConfigurationError.missing(key: key) }
+        return value
+    }
+
+    /// Returns all stored values
     public func dump() -> [Key: String] {
         data
     }
 
+    /// Loads values from the given source
+    /// - Parameter provider: provide values
+    /// - Throws: `ConfigurationError`
     public func load(from provider: ConfigurationProvider) throws {
         try data.merge(provider.configuration(),
                        uniquingKeysWith: { _, new in new })

Sources/Conf/ConfigurationError.swift

@@ -1,5 +1,11 @@
+/// Possible module errors
 public enum ConfigurationError: Error {
+    /// Error during raw data fetching
     case fetch(Error)
+    /// Error during parsing raw data to the specified fortmat
     case parse(Error)
+    /// Error during transforming data to the internal format
     case decode(path: Key, value: Any)
+    /// Missing key requested
+    case missing(key: Key)
 }

Sources/Conf/ConfigurationProvider.swift

@@ -1,6 +1,11 @@
 import Foundation
-
+/// Configuration values provider
+///
+/// Incapsulates configuration values fetching from any source
 public protocol ConfigurationProvider {
+    /// Fetches configuration values
+    ///
+    /// Must throw `ConfigurationError` on error
     func configuration() throws -> [Key: String]
 }
 

Sources/Conf/Fetcher.swift

@@ -12,7 +12,6 @@ extension Fetcher {
     static let file: (String) -> DefaultConfigurationProvider.Fetcher = { configName in
         return {
             let url = URL(fileURLWithPath: configName, isDirectory: false)
-            print(url)
             return try Data(contentsOf: url)
         }
     }