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[WIP]Prevent overriding providers by default (fix #48) #51

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[WIP]Prevent overriding providers by default (fix #48) #51

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3150b0f
code style: break line at 80 chars
vicb Jan 31, 2014
98a06f3
fix test code style
vicb Jan 31, 2014
af5c64e
Prevent overriding providers by default (fix #48)
vicb Jan 31, 2014
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4 changes: 4 additions & 0 deletions lib/errors.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -7,3 +7,7 @@ class NoProviderError extends ArgumentError {
class CircularDependencyError extends ArgumentError {
CircularDependencyError(message) : super(message);
}

class OverrideError extends ArgumentError {
OverrideError(message) : super(message);
}
47 changes: 36 additions & 11 deletions lib/module.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -52,9 +52,10 @@ class Module {
*
* The [value] is what actually will be injected.
*/
void value(Type id, value,
{CreationStrategy creation, Visibility visibility}) {
void value(Type id, value, {CreationStrategy creation, Visibility visibility,
bool allowOverride: false}) {
_dirty();
_checkForExistingId(id, allowOverride);
_providers[id] = new _ValueProvider(value, creation, visibility);
}

Expand All @@ -66,8 +67,9 @@ class Module {
* implied that [id] should be instantiated.
*/
void type(Type id, {Type implementedBy, CreationStrategy creation,
Visibility visibility}) {
Visibility visibility, bool allowOverride: false}) {
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allowOverride should probably just be override. allowOverride makes me think that while defining this type binding I would like to [dis]allow others to override this binding, rather than I might be overriding an existing binding with this one.

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+1

_dirty();
_checkForExistingId(id, allowOverride);
_providers[id] = new _TypeProvider(
implementedBy == null ? id : implementedBy, creation, visibility);
}
Expand All @@ -78,9 +80,10 @@ class Module {
* The [factoryFn] will be called and all its arguments will get injected.
* The result of that function is the value that will be injected.
*/
void factory(Type id, FactoryFn factoryFn,
{CreationStrategy creation, Visibility visibility}) {
void factory(Type id, FactoryFn factoryFn, {CreationStrategy creation,
Visibility visibility, bool allowOverride: false}) {
_dirty();
_checkForExistingId(id, allowOverride);
_providers[id] = new _FactoryProvider(factoryFn, creation, visibility);
}

Expand All @@ -93,12 +96,31 @@ class Module {
_dirty();
}

_dirty() {
void _dirty() {
_providersCache = null;
}

bool get _isDirty =>
_providersCache == null || _childModules.any((m) => m._isDirty);

void _checkForExistingId(Type id, bool allowOverride) {
if (allowOverride) return;
if (_providers.containsKey(id)) {
var binding = _providers[id];
var type;
if (binding is _ValueProvider) {
type = "value";
} else if (binding is _TypeProvider) {
type = "type";
} else if (binding is _FactoryProvider) {
type = "factory";
}
assert(type != null);

throw new OverrideError("'$id' is already registered as a $type "
"provider.");
}
}
}

/** Deafault creation strategy is to instantiate on the defining injector. */
Expand All @@ -117,7 +139,8 @@ abstract class _Provider {

_Provider(this.creationStrategy, this.visibility);

dynamic get(Injector injector, Injector requestor, ObjectFactory getInstanceByType, error);
dynamic get(Injector injector, Injector requestor,
ObjectFactory getInstanceByType, error);
}

class _ValueProvider extends _Provider {
Expand All @@ -127,7 +150,8 @@ class _ValueProvider extends _Provider {
Visibility visibility])
: super(creationStrategy, visibility);

dynamic get(Injector injector, Injector requestor, ObjectFactory getInstanceByType, error) =>
dynamic get(Injector injector, Injector requestor,
ObjectFactory getInstanceByType, error) =>
value;
}

Expand All @@ -138,7 +162,8 @@ class _TypeProvider extends _Provider {
Visibility visibility])
: super(creationStrategy, visibility);

dynamic get(Injector injector, Injector requestor, ObjectFactory getInstanceByType, error) =>
dynamic get(Injector injector, Injector requestor,
ObjectFactory getInstanceByType, error) =>
injector.newInstanceOf(type, getInstanceByType, requestor, error);

}
Expand All @@ -150,6 +175,6 @@ class _FactoryProvider extends _Provider {
Visibility visibility])
: super(creationStrategy, visibility);

dynamic get(Injector injector, Injector requestor, getInstanceByType, error) =>
factoryFn(injector);
dynamic get(Injector injector, Injector requestor, getInstanceByType,
error) => factoryFn(injector);
}
115 changes: 79 additions & 36 deletions test/main.dart
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Expand Up @@ -152,7 +152,6 @@ void main() {
typedef Injector InjectorFactory(List<Module> modules, [String name]);

createInjectorSpec(String injectorName, InjectorFactory injectorFactory) {

describe(injectorName, () {

it('should instantiate a type', () {
Expand Down Expand Up @@ -183,8 +182,8 @@ createInjectorSpec(String injectorName, InjectorFactory injectorFactory) {

it('should inject generic parameterized types', () {
var injector = injectorFactory([new Module()
..type(ParameterizedType)
..type(GenericParameterizedDependency)
..type(ParameterizedType)
..type(GenericParameterizedDependency)
]);
expect(injector.get(GenericParameterizedDependency),
new isInstanceOf<GenericParameterizedDependency>());
Expand All @@ -193,8 +192,8 @@ createInjectorSpec(String injectorName, InjectorFactory injectorFactory) {

xit('should error while resolving parameterized types', () {
var injector = injectorFactory([new Module()
..type(ParameterizedType)
..type(ParameterizedDependency)
..type(ParameterizedType)
..type(ParameterizedDependency)
]);
expect(() => injector.get(ParameterizedDependency), throws);
});
Expand Down Expand Up @@ -224,8 +223,8 @@ createInjectorSpec(String injectorName, InjectorFactory injectorFactory) {

it('should allow providing values', () {
var module = new Module()
..value(Engine, 'str value')
..value(Car, 123);
..value(Engine, 'str value')
..value(Car, 123);

var injector = injectorFactory([module]);
var abcInstance = injector.get(Engine);
Expand Down Expand Up @@ -261,10 +260,9 @@ createInjectorSpec(String injectorName, InjectorFactory injectorFactory) {

it('should inject injector into factory function', () {
var module = new Module()
..type(Engine)
..factory(Car, (Injector injector) {
return new Car(injector.get(Engine), injector);
});
..type(Engine)
..factory(Car, (Injector injector) =>
new Car(injector.get(Engine), injector));

var injector = injectorFactory([module]);
var instance = injector.get(Car);
Expand All @@ -277,11 +275,11 @@ createInjectorSpec(String injectorName, InjectorFactory injectorFactory) {
it('should throw an exception when injecting a primitive type', () {
var injector = injectorFactory([
new Module()
..type(NumDependency)
..type(IntDependency)
..type(DoubleDependency)
..type(BoolDependency)
..type(StringDependency)
..type(NumDependency)
..type(IntDependency)
..type(DoubleDependency)
..type(BoolDependency)
..type(StringDependency)
]);

expect(() {
Expand Down Expand Up @@ -312,13 +310,13 @@ createInjectorSpec(String injectorName, InjectorFactory injectorFactory) {


it('should throw an exception when circular dependency', () {
var injector = injectorFactory([new Module()..type(CircularA)..type(CircularB)]);
var injector = injectorFactory([new Module()..type(CircularA)
..type(CircularB)]);

expect(() {
injector.get(CircularA);
}, toThrow(CircularDependencyError, 'Cannot resolve a circular dependency! '
'(resolving CircularA -> '
'CircularB -> CircularA)'));
}, toThrow(CircularDependencyError, 'Cannot resolve a circular '
'dependency! (resolving CircularA -> CircularB -> CircularA)'));
});


Expand Down Expand Up @@ -462,9 +460,9 @@ createInjectorSpec(String injectorName, InjectorFactory injectorFactory) {
it('should instantiate class only once (Issue #18)', () {
var injector = injectorFactory([
new Module()
..type(Log)
..type(ClassOne)
..factory(InterfaceOne, (i) => i.get(ClassOne))
..type(Log)
..type(ClassOne)
..factory(InterfaceOne, (i) => i.get(ClassOne))
]);

expect(injector.get(InterfaceOne), same(injector.get(ClassOne)));
Expand All @@ -483,8 +481,8 @@ createInjectorSpec(String injectorName, InjectorFactory injectorFactory) {
}

var parentModule = new Module()
..type(Engine, implementedBy: MockEngine, creation: creation)
..type(Car, creation: creation);
..type(Engine, implementedBy: MockEngine, creation: creation)
..type(Car, creation: creation);

var parentInjector = injectorFactory([parentModule]);
var childInjector = parentInjector.createChild([]);
Expand All @@ -503,7 +501,7 @@ createInjectorSpec(String injectorName, InjectorFactory injectorFactory) {
}

var module = new Module()
..type(Engine, implementedBy: MockEngine, creation: creation);
..type(Engine, implementedBy: MockEngine, creation: creation);
var injector = injectorFactory([module]);
expect(() {
injector.get(Engine);
Expand All @@ -515,38 +513,83 @@ createInjectorSpec(String injectorName, InjectorFactory injectorFactory) {
describe('visiblity', () {

it('should hide instances', () {

var rootMock = new MockEngine();
var childMock = new MockEngine();

var parentModule = new Module()
..value(Engine, rootMock);
var parentModule = new Module()..value(Engine, rootMock);
var childModule = new Module()
..value(Engine, childMock, visibility: (_, __) => false);
..value(Engine, childMock, visibility: (_, __) => false);

var parentInjector = injectorFactory([parentModule]);
var childInjector = parentInjector.createChild([childModule]);

var val = childInjector.get(Engine);
expect(val, same(rootMock));
expect(childInjector.get(Engine), same(rootMock));
});

it('should throw when an instance in not visible in the root injector', () {
var module = new Module()
..value(Car, 'Invisible', visibility: (_, __) => false);
..value(Car, 'Invisible', visibility: (_, __) => false);

var injector = injectorFactory([module]);

expect(() {
injector.get(Car);
}, toThrow(
NoProviderError,
'No provider found for Car! (resolving Car)'
NoProviderError, 'No provider found for Car! (resolving Car)'
));
});

});
describe('override', () {

it('should prevent overriding a provider by default', () {
expect(() {
new Module()
..value(Engine, null)
..value(Engine, new MockEngine());
}, toThrow(
OverrideError, "'Engine' is already registered as a value provider"
));

expect(() {
new Module()
..value(Engine, null)
..type(Engine);
}, toThrow(
OverrideError, "'Engine' is already registered as a value provider"
));

expect(() {
new Module()
..value(Engine, null)
..factory(Engine, (_) => null);
}, toThrow(
OverrideError, "'Engine' is already registered as a value provider"
));
});
});

it('should allow overriding a provider', () {
var module;
var injector;

var value = new MockEngine2();
module = new Module()
..value(Engine, null)
..value(Engine, value, allowOverride: true);
expect(injectorFactory([module]).get(Engine), same(value));

module = new Module()
..value(Engine, null)
..type(Engine, allowOverride: true);
expect(injectorFactory([module]).get(Engine), instanceOf(Engine));

module = new Module()
..value(Engine, null)
..factory(Engine, (_) => new Engine(), allowOverride: true);
expect(injectorFactory([module]).get(Engine), instanceOf(Engine));
});

});
});

}