Add constructor injection to documentation

This commit is contained in:
Mike Bierlee 2016-08-23 21:10:31 +02:00
parent ab765e0092
commit 44c41b1579
3 changed files with 39 additions and 5 deletions

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@ -1,6 +1,7 @@
Poodinis Changelog
==================
**Version 7.0.0**
* ADD constructor injection. Injection is done automatically on resolve. See tutorial and examples for more details.
* REMOVE deprecated registration options. They are still available in properly cased forms.
* REMOVE deprecated register() and resolve() methods which accept variadics and arrays for options.
Since registration and resolve options have become bitfields, you should specify them with logical ANDs.

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@ -6,7 +6,7 @@ Licensed under the terms of the MIT license - See [LICENSE.txt](LICENSE.txt)
Master: [![Build Status](https://api.travis-ci.org/mbierlee/poodinis.png?branch=master)](https://travis-ci.org/mbierlee/poodinis) - Dev: [![Build Status](https://api.travis-ci.org/mbierlee/poodinis.png?branch=develop)](https://travis-ci.org/mbierlee/poodinis)
Poodinis is a dependency injection framework for the D programming language. It is inspired by the [Spring Framework] and [Hypodermic] IoC container for C++. Poodinis supports registering and resolving classes either by concrete type or interface. Automatic injection of dependencies is supported through the use of UDAs (Referred to as autowiring).
Poodinis is a dependency injection framework for the D programming language. It is inspired by the [Spring Framework] and [Hypodermic] IoC container for C++. Poodinis supports registering and resolving classes either by concrete type or interface. Automatic injection of dependencies is supported through the use of UDAs or constructors.
Requires at least a D 2.068.0 compatible compiler
Uses the Phobos standard library
@ -59,7 +59,6 @@ Future Work
-----------
* Component scan (auto-registration)
* Phobos collections autowiring
* Constructor injection
* Named qualifiers
* Value type injection

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@ -68,7 +68,9 @@ dependencies.register!ExampleClass.existingInstance(preExistingInstance);
Autowiring
----------
The real value of any dependency injection framework comes from its ability to autowire dependencies. Poodinis supports autowiring by simply applying the `@Autowire` UDA to a member of a class:
The real value of any dependency injection framework comes from its ability to automatically inject dependencies. Poodinis supports automatic injection either through autowiring members annotated with the `@Autowire` UDA or through constructor injection.
### UDA-based autowiring
UDA-based autowiring can be achieved by annotating members of a class with the `@Autowire` UDA:
```d
class ExampleClassA {}
@ -79,8 +81,13 @@ class ExampleClassB {
dependencies.register!ExampleClassA;
auto exampleInstance = new ExampleClassB();
// Manual autowiring
dependencies.autowire(exampleInstance);
assert(exampleInstance.dependency !is null);
// Let the container handle injection
dependencies.register!ExampleClassB;
auto exampleInstance2 = dependencies.resolve!ExampleClassB;
```
It is possible to autowire public as well as protected and private members.
@ -104,6 +111,33 @@ class ExampleClass {
}
```
### Constructor injection
Poodinis also supports automatic injection of dependencies through constructors:
```d
class ExampleClassA {}
class ExampleClassB {
private ExampleClassA dependency;
this(ExampleClassA dependency) {
this.dependency = dependency;
}
}
dependencies.register!ExampleClassA;
dependencies.register!ExampleClassB;
auto instance = dependencies.resolve!ExampleClassB;
```
`ExampleClassA` is automatically resolved and passed to `ExampleClassB`'s constructor.
Classes with multiple constructors can be injected. The following rules apply to constructor injection:
* Injection is attempted at the order of declaration. However, this is compiler dependant and may not always be the case.
* Injection is attempted for the first constructor which has non-builtin types only in its parameter list.
* When a constructor with an empty parameter list is found, no other constructors are attempted (and nothing is injected). This can be used to explicitly prevent constructor injection.
* When no injectable constructor is found an InstanceCreationException will be thrown on resolve.
If the constructors of a class are not suitable for injection, you could manually configure its creation using Application Contexts (see chapter further down).
Circular dependencies
---------------------
Poodinis can autowire circular dependencies when they are registered with `singleInstance` or `existingInstance` registration scopes. Circular dependencies in registrations with `newInstance` scopes will not be autowired, as this would cause an endless loop.