Mutability homework submission

elm-todo/Todo.elm

@@ -45,7 +45,6 @@ type alias Model =
 type alias Entry =
     { description : String
     , completed : Bool
-    , editing : Bool
     , id : Int
     }
 
@@ -62,7 +61,6 @@ newEntry : String -> Int -> Entry
 newEntry desc id =
     { description = desc
     , completed = False
-    , editing = False
     , id = id
     }
 
@@ -76,14 +74,13 @@ to them.
 -}
 type Msg
     = UpdateNewEntryField String
-    | EditingEntry Int Bool
-    | UpdateEntry Int String
     | Add
     | Delete Int
     | DeleteAllCompleted
     | Check Int Bool
 
 
+
 -- How we update our Model on a given Msg?
 update : Msg -> Model -> Model
 update msg model =
@@ -102,29 +99,6 @@ update msg model =
         UpdateNewEntryField str ->
             { model | newEntryField = str }
 
-        EditingEntry id isEditing ->
-            let
-                updateEntry t =
-                    if t.id == id then
-                        { t | editing = isEditing }
-                    else
-                        t
-
-                focus =
-                    Dom.focus ("todo-" ++ toString id)
-            in
-                { model | entries = List.map updateEntry model.entries }
-
-        UpdateEntry id task ->
-            let
-                updateEntry t =
-                    if t.id == id then
-                        { t | description = task }
-                    else
-                        t
-            in
-                { model | entries = List.map updateEntry model.entries }
-
         Check id isCompleted ->
             let
                 updateEntry t =
@@ -229,7 +203,7 @@ viewKeyedEntry todo =
 viewEntry : Entry -> Html Msg
 viewEntry todo =
     li
-        [ classList [ ( "completed", todo.completed ), ( "editing", todo.editing ) ] ]
+        [ classList [ ( "completed", todo.completed )] ]
         [ div
             [ class "view" ]
             [ input
@@ -240,28 +214,17 @@ viewEntry todo =
                 ]
                 []
             , label
-                [ onDoubleClick (EditingEntry todo.id True) ]
+                []
                 [ text todo.description ]
             , button
                 [ class "destroy"
                 , onClick (Delete todo.id)
                 ]
                 []
             ]
-        , input
-            [ class "edit"
-            , value todo.description
-            , name "title"
-            , id ("todo-" ++ toString todo.id)
-            , onInput (UpdateEntry todo.id)
-            , onBlur (EditingEntry todo.id False)
-            , onEnter (EditingEntry todo.id False)
-            ]
-            []
         ]
 
 
-
 -- VIEW CONTROLS AND FOOTER
 
 
@@ -313,8 +276,7 @@ viewControlsClear entriesCompleted =
 infoFooter : Html msg
 infoFooter =
     footer [ class "info" ]
-        [ p [] [ text "Double-click to edit a todo" ]
-        , p []
+        [ p []
             [ text "Written by "
             , a [ href "https://github.com/evancz" ] [ text "Evan Czaplicki" ]
             ]

ruby-todo/lib/engine.rb

@@ -5,7 +5,7 @@ def self.run(*args)
 
   def self.run_with_history(model, messages)
     messages.map do |msg|
-      msg.apply_to(model)
+      model = msg.apply_to(model)
       model
     end
   end

ruby-todo/lib/messages.rb

@@ -2,13 +2,25 @@ module Msg
 
   class Add
     def apply_to(model)
+      # copy model.entries to a new array of entries
+      new_entries = []
+      model.entries.each do |entry|
+        new_entries << Entry.new(
+          id: entry.id, 
+          description: entry.description, 
+          completed: entry.completed)
+      end
+
       unless model.new_entry_field.blank?
-        model.entries << Entry.new(
+        new_entries << Entry.new(
           description: model.new_entry_field,
           id: model.next_id)
       end
-      model.next_id += 1
-      model.new_entry_field = ""
+
+      Model.new(
+        entries: new_entries, 
+        new_entry_field: "", 
+        next_id: model.next_id + 1)
     end
   end
 
@@ -20,7 +32,19 @@ def initialize(str)
     attr_reader :str 
 
     def apply_to(model)
-      model.new_entry_field = str
+      # copy model.entries to a new array of entries
+      new_entries = []
+      model.entries.each do |entry|
+        new_entries << Entry.new(
+          id: entry.id, 
+          description: entry.description, 
+          completed: entry.completed)
+      end
+
+      Model.new(
+        entries: new_entries,
+        new_entry_field: str, 
+        next_id: model.next_id)
     end
   end
 
@@ -32,11 +56,18 @@ def initialize(id, is_completed)
     attr_reader :id, :is_completed 
 
     def apply_to(model)
+      new_entries = []
       model.entries.each do |entry|
-        if entry.id == id
-          entry.completed = is_completed
-        end
+        new_complete_status = (entry.id == id) ? is_completed : entry.completed
+        new_entries << Entry.new(
+          id: entry.id, 
+          description: entry.description, 
+          completed: new_complete_status) 
       end
+      Model.new(
+        entries: new_entries,
+        new_entry_field: model.new_entry_field, 
+        next_id: model.next_id)
     end
   end
 
@@ -48,13 +79,35 @@ def initialize(id)
     attr_reader :id 
 
     def apply_to(model)
-      model.entries.reject! { |e| e.id == id }
+      new_entries = []
+      model.entries.each do |entry|
+        new_entries << Entry.new(
+          id: entry.id, 
+          description: entry.description, 
+          completed: entry.completed)
+      end
+      new_entries.reject! { |e| e.id == id }
+      Model.new(
+        entries: new_entries,
+        new_entry_field: model.new_entry_field, 
+        next_id: model.next_id)
     end
   end
 
   class DeleteAllCompleted
     def apply_to(model)
-      model.entries.reject!(&:completed)
+      new_entries = []
+      model.entries.each do |entry|
+        new_entries << Entry.new(
+          id: entry.id, 
+          description: entry.description, 
+          completed: entry.completed)
+      end
+      new_entries.reject!(&:completed)
+      Model.new(
+        entries: new_entries,
+        new_entry_field: model.new_entry_field, 
+        next_id: model.next_id)
     end
   end
 

ruby-todo/lib/model.rb

@@ -5,7 +5,7 @@ def initialize(entries: [], new_entry_field: "", next_id: nil)
       (entries.lazy.map(&:id).max || -1) + 1
   end
 
-  attr_accessor :entries, :new_entry_field, :next_id
+  attr_reader :entries, :new_entry_field, :next_id
 
   def ==(other)
     !other.nil? &&

ruby-todo/test/test_helper.rb

@@ -8,5 +8,5 @@
 
 # To see full test names when running tests:
 #
-# require "minitest/reporters"
-# Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
+require "minitest/reporters"
+Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new

ruby-todo/test/todo_test.rb

@@ -91,7 +91,7 @@
   end
 
   it "supports time travel" do
-    skip "Mutable model does not support time travel"
+    # skip "Mutable model does not support time travel"
 
     actual_history = Engine.run_with_history(Model.new, [
       Msg::UpdateNewEntryField.new("go forward in time"),
@@ -163,4 +163,4 @@
     end
   end
 
-end
+end

swift-todo/Sources/Todo/Engine.swift

@@ -13,9 +13,10 @@ struct Engine {
     }
 
     static func runWithHistory(on model: Model, applying messages: [Message]) -> [Model] {
+        var newModel = model
         return messages.map { message in
-          message.apply(to: model)
-          return model
+            newModel = message.apply(to: newModel)
+            return newModel
         }
     }
 }

swift-todo/Sources/Todo/Message.swift

@@ -14,30 +14,40 @@ enum Message {
     case delete(Int)
     case deleteAllCompleted
 
-    func apply(to model: Model) {
+    func apply(to model: Model) -> Model {
         switch(self) {
             case .add:
+                var model = model
                 if !model.newEntryField.isBlank() {
                     model.entries.append(Entry(id: model.nextID, description: model.newEntryField))
                 }
                 model.nextID += 1
                 model.newEntryField = ""
+                return model
 
             case .updateNewEntryField(let str):
+                var model = model
                 model.newEntryField = str
+                return model
 
             case .check(let id, let isCompleted):
-                for entry in model.entries {
-                    if(entry.id == id) {
-                        entry.completed = isCompleted
+                var model = model
+                for (index, _) in model.entries.enumerated() {
+                    if(model.entries[index].id == id) {
+                        model.entries[index].completed = isCompleted
                     }
                 }
+                return model
 
             case .delete(let id):
+                var model = model
                 model.entries.remove { $0.id == id }
+                return model
 
             case .deleteAllCompleted:
+                var model = model
                 model.entries.remove { $0.completed }
+                return model
         }
     }
 }

swift-todo/Sources/Todo/Model.swift

@@ -1,4 +1,4 @@
-class Model {
+struct Model {
     var entries: [Entry]
     var newEntryField: String
     var nextID: Int
@@ -11,7 +11,7 @@ class Model {
     }
 }
 
-class Entry {
+struct Entry {
     var id: Int
     var description: String
     var completed: Bool

swift-todo/Tests/TodoTests/TodoTests.swift

@@ -26,6 +26,7 @@ class TodoTests: XCTestCase {
              .updateNewEntryField("hop on one foot"),
              .add
          ])
+
          XCTAssertEqual(3, newModel.entries.count)
          let newEntry = newModel.entries.last!
          XCTAssertEqual(12, newEntry.id)
@@ -77,7 +78,7 @@ class TodoTests: XCTestCase {
          XCTAssertEqual([11], newModel.entries.map { $0.id })
      }
 
-/*
+
      func testTimeTravel() {
         let actualHistory = Engine.runWithHistory(on: Model(), applying: [
              .updateNewEntryField("go forward in time"),
@@ -145,6 +146,6 @@ class TodoTests: XCTestCase {
              XCTAssertEqual(expected, actual, "History mismatch at step \(index)")
          }
     }
-*/
+
 
 }