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* Delete container var. Use type Container instead. * Sort methods in container. * Fix tests. * Move container definition to the pkg directory. Create default container instance. * Update readme. Co-authored-by: Przemyslaw Materna <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,131 @@ | ||
| // Package container provides an IoC container for Go projects. | ||
| // It provides simple, fluent and easy-to-use interface to make dependency injection in GoLang easier. | ||
| package container | ||
|
|
||
| import ( | ||
| "reflect" | ||
| ) | ||
|
|
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| // binding keeps a binding resolver and instance (for singleton bindings). | ||
| type binding struct { | ||
| resolver interface{} // resolver function | ||
| instance interface{} // instance stored for singleton bindings | ||
| } | ||
|
|
||
| // resolve will return the concrete of related abstraction. | ||
| func (b binding) resolve(c Container) interface{} { | ||
| if b.instance != nil { | ||
| return b.instance | ||
| } | ||
|
|
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| return c.invoke(b.resolver) | ||
| } | ||
|
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| // Container is a map of reflect.Type to binding | ||
| type Container map[reflect.Type]binding | ||
|
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| // NewContainer returns a new instance of Container | ||
| func NewContainer() Container { | ||
| return make(Container) | ||
| } | ||
|
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| // bind will map an abstraction to a concrete and set instance if it's a singleton binding. | ||
| func (c Container) bind(resolver interface{}, singleton bool) { | ||
| resolverTypeOf := reflect.TypeOf(resolver) | ||
| if resolverTypeOf.Kind() != reflect.Func { | ||
| panic("the resolver must be a function") | ||
| } | ||
|
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| for i := 0; i < resolverTypeOf.NumOut(); i++ { | ||
| var instance interface{} | ||
| if singleton { | ||
| instance = c.invoke(resolver) | ||
| } | ||
|
|
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| c[resolverTypeOf.Out(i)] = binding{ | ||
| resolver: resolver, | ||
| instance: instance, | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // invoke will call the given function and return its returned value. | ||
| // It only works for functions that return a single value. | ||
| func (c Container) invoke(function interface{}) interface{} { | ||
| return reflect.ValueOf(function).Call(c.arguments(function))[0].Interface() | ||
| } | ||
|
|
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| // arguments will return resolved arguments of the given function. | ||
| func (c Container) arguments(function interface{}) []reflect.Value { | ||
| functionTypeOf := reflect.TypeOf(function) | ||
| argumentsCount := functionTypeOf.NumIn() | ||
| arguments := make([]reflect.Value, argumentsCount) | ||
|
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| for i := 0; i < argumentsCount; i++ { | ||
| abstraction := functionTypeOf.In(i) | ||
|
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| var instance interface{} | ||
|
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| if concrete, ok := c[abstraction]; ok { | ||
| instance = concrete.resolve(c) | ||
| } else { | ||
| panic("no concrete found for the abstraction: " + abstraction.String()) | ||
| } | ||
|
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| arguments[i] = reflect.ValueOf(instance) | ||
| } | ||
|
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| return arguments | ||
| } | ||
|
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| // Singleton will bind an abstraction to a concrete for further singleton resolves. | ||
| // It takes a resolver function which returns the concrete and its return type matches the abstraction (interface). | ||
| // The resolver function can have arguments of abstraction that have bound already in Container. | ||
| func (c Container) Singleton(resolver interface{}) { | ||
| c.bind(resolver, true) | ||
| } | ||
|
|
||
| // Transient will bind an abstraction to a concrete for further transient resolves. | ||
| // It takes a resolver function which returns the concrete and its return type matches the abstraction (interface). | ||
| // The resolver function can have arguments of abstraction that have bound already in Container. | ||
| func (c Container) Transient(resolver interface{}) { | ||
| c.bind(resolver, false) | ||
| } | ||
|
|
||
| // Reset will reset the container and remove all the bindings. | ||
| func (c Container) Reset() { | ||
| for k := range c { | ||
| delete(c, k) | ||
| } | ||
| } | ||
|
|
||
| // Make will resolve the dependency and return a appropriate concrete of the given abstraction. | ||
| // It can take an abstraction (interface reference) and fill it with the related implementation. | ||
| // It also can takes a function (receiver) with one or more arguments of the abstractions (interfaces) that need to be | ||
| // resolved, Container will invoke the receiver function and pass the related implementations. | ||
| func (c Container) Make(receiver interface{}) { | ||
| receiverTypeOf := reflect.TypeOf(receiver) | ||
| if receiverTypeOf == nil { | ||
| panic("cannot detect type of the receiver, make sure your are passing reference of the object") | ||
| } | ||
|
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| if receiverTypeOf.Kind() == reflect.Ptr { | ||
| abstraction := receiverTypeOf.Elem() | ||
|
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| if concrete, ok := c[abstraction]; ok { | ||
| instance := concrete.resolve(c) | ||
| reflect.ValueOf(receiver).Elem().Set(reflect.ValueOf(instance)) | ||
| return | ||
| } | ||
|
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| panic("no concrete found for the abstraction " + abstraction.String()) | ||
| } | ||
|
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| if receiverTypeOf.Kind() == reflect.Func { | ||
| arguments := c.arguments(receiver) | ||
| reflect.ValueOf(receiver).Call(arguments) | ||
| return | ||
| } | ||
|
|
||
| panic("the receiver must be either a reference or a callback") | ||
| } |
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