1 /**
2 Aedi, a dependency injection library.
3 
4 Aedi is a dependency injection library. It does provide a set of containers that do
5 IoC, and an interface to configure application components (structs, objects, etc.)
6 
7 Aim:
8 The aim of library is to provide a dependency injection solution that is
9 feature rich, easy to use, easy to learn, and easy to extend up to your needs.
10 
11 This tutorial will show how to register several components, and reference them
12 as dependencies.
13 
14 Just registering a component with predefined data, is not enough even in smallest applications,
15 since an application is an amalgamation of interconnected components. Therefore the framework does
16 allow client code to register components that have dependencies, and reference them in configuration
17 of those components.
18 
19 For example, in application that simulates cars, a car clearly is not a single god object. It is a
20 set of interconnected components, represented by objects in application. Though as seen in listing,
21 the car has it’s color and size hard-coded to specific values, and modifications to them aren’t
22 possible to do. Having a car simulator such code is not desired, since a simulator should be able
23 to simulate multiple types of cars with different sizes and colors.
24 
25 ------------------
26 class Car {
27     private Color color_;
28     private Size size;
29 
30     public this() {
31         color_ = Color(255, 255, 100);
32         sizes = Size(200, 150, 500);
33     }
34 }
35 ------------------
36 
37 In improvement to the defined car in application (above), could be done by exposing color and size of
38 car to configuration from exterior environment
39 
40 ------------------
41 class Car {
42     private Color color_;
43     private Size size;
44 
45     public this(Size size) {
46         this.size = size;
47     }
48 
49     public @property void color(Color color) {
50         this.color_ = color;
51     }
52 }
53 
54 void main() {
55     Car myCar = new Car(Size(200, 150, 500));
56     myCar.color = Color(0, 255, 0);
57 }
58 ------------------
59 
60 Having the ability to change color and size of a car it is possible to have now multiple instances
61 of a car, with different sizes and colors, though with increase of different types cars, the amount
62 of code required to instantiate and configure them with right sizes increases tremendously, and in
63 the end can become complex, and cumbersome to understand. Not to mention, the importance of
64 micromanaging the order of how cars component instantiate. A car cannot be instantiated before, her
65 components. Clearly the solution is more flexible, yet at a cost of increased amount of code.
66 
67 A DI framework aims to lessen the burden of writing wiring code, and will eliminate the need
68 of micromanaging the order component creation. It will do instead of developers, just like in following
69 example
70 
71 ------------------
72 SingletonContainer container = singleton(); // Creating container that will manage a color
73 
74 with (container.configure) {
75 
76     register!Color // Register color into container.
77         .set!"r"(cast(ubyte) 0) // Set red color to 0
78         .set!"g"(cast(ubyte) 255) // Set green color to 255
79         .set!"b"(cast(ubyte) 0); // Set blue color to 0
80 
81     register!Size // Register a size into container
82         .set!"width"(200UL) // As for color set width to 150.
83         .set!"height"(150UL)
84         .set!"length"(500UL);
85 
86     register!Car // Register a car in container
87         .construct(lref!Size) // Construct car using size present in container
88         .set!"color"(lref!Color); // Set car color to color present in container.
89 }
90 
91 container.instantiate(); // Boot container (or prepare managed code/data).
92 
93 container.locate!Car.print;
94 ------------------
95 
96 Referencing a dependency in a Car can be done using $(D_INLINECODE lref!Type) notation, that allows
97 framework to detect that a dependency is actually required to pass, and not a simple value. Therefore
98 the framework will search for a value of a type $(D_INLINECODE Type) and pass it as a dependency to Car.
99 The result of a container can be seen by fetching a car from container and printing it to the
100 stdout
101 
102 At end we should see the car:
103 ------------------
104 You bought a new car with following specs:
105 Size:	Size(200, 150, 500)
106 Color:	Color(0, 255, 0)
107 ------------------
108 
109 Try example in this module. Modify it, play with it to understand how to configure dependencies
110 between components.
111 
112 License:
113 	Boost Software License - Version 1.0 - August 17th, 2003
114 
115 	Permission is hereby granted, free of charge, to any person or organization
116 	obtaining a copy of the software and accompanying documentation covered by
117 	this license (the "Software") to use, reproduce, display, distribute,
118 	execute, and transmit the Software, and to prepare derivative works of the
119 	Software, and to permit third-parties to whom the Software is furnished to
120 	do so, all subject to the following:
121 
122 	The copyright notices in the Software and this entire statement, including
123 	the above license grant, this restriction and the following disclaimer,
124 	must be included in all copies of the Software, in whole or in part, and
125 	all derivative works of the Software, unless such copies or derivative
126 	works are solely in the form of machine-executable object code generated by
127 	a source language processor.
128 
129 	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
130 	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
131 	FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
132 	SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
133 	FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
134 	ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
135 	DEALINGS IN THE SOFTWARE.
136 
137 Authors:
138 	aermicioi
139 **/
140 
141 module dependencies;
142 
143 import aermicioi.aedi;
144 import std.stdio;
145 
146 /**
147 A struct that should be managed by container.
148 **/
149 struct Color {
150     ubyte r;
151     ubyte g;
152     ubyte b;
153 }
154 
155 /**
156 Size of a car.
157 **/
158 struct Size {
159 
160     ulong width;
161     ulong height;
162     ulong length;
163 }
164 
165 /**
166 A class representing a car.
167 **/
168 class Car {
169 
170     private {
171         Color color_; // Car color
172         Size size_; // Car size
173     }
174 
175     public {
176 
177         /**
178         Constructor of car.
179 
180         Constructs a car with a set of sizes. A car cannot of course have
181         undefined sizes, so we should provide it during construction.
182 
183         Params:
184             size = size of a car.
185         **/
186         this(Size size) {
187             this.size_ = size;
188         }
189 
190         @property {
191 
192             /**
193             Set color of car
194 
195             Set color of car. A car can live with undefined color (physics allow it).
196 
197             Params:
198             	color = color of a car.
199 
200             Returns:
201             	Car
202             **/
203             Car color(Color color) @safe nothrow {
204             	this.color_ = color;
205 
206             	return this;
207             }
208 
209             Color color() @safe nothrow {
210             	return this.color_;
211             }
212 
213             Size size() @safe nothrow {
214             	return this.size_;
215             }
216         }
217     }
218 }
219 
220 void print(Car car) {
221     "You bought a new car with following specs:".writeln;
222     writeln("Size:\t", car.size());
223     writeln("Color:\t", car.color());
224 }
225 
226 void main() {
227     SingletonContainer container = singleton(); // Creating container that will manage a color
228     scope(exit) container.terminate();
229 
230     with (container.configure) {
231 
232         register!Color // Register color into container.
233             .set!"r"(cast(ubyte) 0) // Set red color to 0
234             .set!"g"(cast(ubyte) 255) // Set green color to 255
235             .set!"b"(cast(ubyte) 0); // Set blue color to 0
236 
237         register!Size // Register a size into container
238             .set!"width"(200UL) // As for color set width to 150.
239             .set!"height"(150UL)
240             .set!"length"(500UL);
241 
242         register!Car // Register a car in container
243             .construct(lref!Size) // Construct car using size present in container
244             .set!"color"(lref!Color); // Set car color to color present in container.
245     }
246 
247     container.instantiate(); // Boot container (or prepare managed code/data).
248 
249     container.locate!Car.print; // Get color from container and print it.
250 }