Toothpick Bad Practices 🙅 and Nice Tricks 👌

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BAD PRACTICES AND NICE TRICKS " TOOTHPICK

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SCOPE INJECTING STUFF: GRAPH AND ROOT FACTORIES & MEMBER INJECTORS SCOPE LIFECYCLE APPLICATION SCOPE ACTIVITY SCOPE LAZIES & SCOPES CONTEXT & SCOPES SUPPRESS WARNING UNIT TESTING THE TALK

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public class DealDetailActivity extends Activity { public static final String EXTRA_DEAL_ID = "EXTRA_DEAL_ID"; public static final String EXTRA_SHOW_MAP = "EXTRA_SHOW_MAP"; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Scope scope = Toothpick.openScope(this); Toothpick.inject(this, scope); ... } SCOPE 1. OPEN SCOPE 2. INJECTING USING SCOPE

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SCOPE 1. TP INJECT TP # inject A

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SCOPE 1. TP INJECT TP # inject A SCOPE 2. TP USES SCOPE TO INJECT

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SCOPE 1. TP INJECT TP # inject A SCOPE 2. TP USES SCOPE TO INJECT

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SCOPE MAKES THE INJECTIONS SCOPE

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INJECTING STUFF: GRAPH AND ROOT A D B C E F G

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INJECTING STUFF: GRAPH AND ROOT public class A extends Activity { @Inject B b; @Inject C c; } public class B extends Fragment { @Inject D d; @Inject E e; } public class C extends Fragment { @Inject F f; } public class E extends View { @Inject G g; } A D B C E F G

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A D B C E F G public class A extends Activity { @Inject B b; @Inject C c; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Scope scope = Toothpick.openScope(this); Toothpick.inject(this, scope); ... } INJECTING STUFF: GRAPH AND ROOT

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A D B C E F G DI root public class A extends Activity { @Inject B b; @Inject C c; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Scope scope = Toothpick.openScope(this); Toothpick.inject(this, scope); ... } INJECTING STUFF: GRAPH AND ROOT

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A D B C E F G DI root 1. CREATE 2. INJECT FACTORIES & MEMBER INJECTORS class B$$Factory implements Factory { public B createInstance(Scope scope) { scope = getTargetScope(scope); B b = new B(); memberInjector.inject(b, scope); return b; } } class A$$MemberInjector implements MI { public A inject(A a, Scope scope) { a.b = scope.getInstance(B.class); a.c = scope.getInstance(C.class); } }

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A D B C E F G DI root 1. CREATE 2. INJECT FACTORIES & MEMBER INJECTORS B C class B$$Factory implements Factory { public B createInstance(Scope scope) { scope = getTargetScope(scope); B b = new B(); memberInjector.inject(b, scope); return b; } } class A$$MemberInjector implements MI { public A inject(A a, Scope scope) { a.b = scope.getInstance(B.class); a.c = scope.getInstance(C.class); } }

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A D B C E F G DI root 1. CREATE 2. INJECT FACTORIES & MEMBER INJECTORS B C D E F class B$$Factory implements Factory { public B createInstance(Scope scope) { scope = getTargetScope(scope); B b = new B(); memberInjector.inject(b, scope); return b; } } class A$$MemberInjector implements MI { public A inject(A a, Scope scope) { a.b = scope.getInstance(B.class); a.c = scope.getInstance(C.class); } }

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A D B C E F G DI root 1. CREATE 2. INJECT FACTORIES & MEMBER INJECTORS B C D E F G class B$$Factory implements Factory { public B createInstance(Scope scope) { scope = getTargetScope(scope); B b = new B(); memberInjector.inject(b, scope); return b; } } class A$$MemberInjector implements MI { public A inject(A a, Scope scope) { a.b = scope.getInstance(B.class); a.c = scope.getInstance(C.class); } }

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SCOPE LIFECYCLE APPLICATION  SCOPE

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SCOPE LIFECYCLE APPLICATION  SCOPE ACTIVITY  SCOPE

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SCOPE LIFECYCLE APPLICATION  SCOPE

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public class DealDetailActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Scope scope = Toothpick.openScope(this); Toothpick.closeScope(this); Toothpick.inject(this, scope); ... } } SCOPE LIFECYCLE CLOSED SCOPES CANNOT BE USED

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SCOPE LIFECYCLE Crash DO NOT USE ACTIVITY SCOPE AFTER ONDESTROY CALLBACKS NETWORK CODE RX ASYNC CODE EVENT BUS LISTENERS

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SCOPE LIFECYCLE

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LAZIES & SCOPES %

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public class A extends Activity { @Inject Lazy b; @Inject C c; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Scope scope = Toothpick.openScope(this); Toothpick.inject(this, scope); ... } public void onDestroy() { Toothpick.closeScope(this); } public void afterOnDestroy() { b.get().someMethod(); } public class A extends Activity { @Inject Lazy b; @Inject C c; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Scope scope = Toothpick.openScope(application); Toothpick.inject(this, scope); ... } public void onDestroy() { Toothpick.closeScope(this); } public void afterOnDestroy() { b.get().someMethod(); } LAZIES & SCOPES LAZY ACTIVITY  SCOPE APPLICATION SCOPE

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APPLICATION  SCOPE ACTIVITY  SCOPE APP SINGLETONS ACTIVITY SINGLETONS LAZIES & SCOPES

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FACTORIES & MEMBER INJECTORS A D B C E F G @Singleton Lazy

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FACTORIES & MEMBER INJECTORS A D B C E F G @Singleton ACTIVITY SCOPE Lazy

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FACTORIES & MEMBER INJECTORS A D B C E F G @Singleton ACTIVITY SCOPE APPLICATION SCOPE Lazy

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Crash DO NOT USE LAZY.GET() AFTER ONDESTROY CALLBACKS NETWORK CODE RX ASYNC CODE LAZIES & SCOPES EVENT BUS LISTENERS

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LAZIES & SCOPES

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CONTEXT & SCOPES public class DealView extends FrameLayout { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Context context = getContext(); if (!context instanceof Activity) { throw new ThisIsBadException(); } ... } CONTEXT CAN BE DIFFERENT FROM ACTIVITY: CONTEXTWRAPPER

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CONTEXT & SCOPES public class DealView extends FrameLayout { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Context context = getContext(); if (!context instanceof Activity) { throw new ThisIsBadException(); } ... } Crash CONTEXT CAN BE DIFFERENT FROM ACTIVITY: CONTEXTWRAPPER

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public class DealView extends FrameLayout { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Context context = getContext(); Scope scope = Toothpick.openScope(context); ... } } ACTIVITY SCOPE != CONTEXT SCOPE CONTEXT & SCOPES

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public class DealView extends FrameLayout { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Context context = getContext(); Scope scope = ContextScopeFinder.getScope(context); ... } } CONTEXT SCOPE FINDER FINDS THE ACTIVITY SCOPE FOR US CONTEXT & SCOPES

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GtgDealCardViewHandler.java:17: warning: The class com.groupon.gtg.mga.customview.ildcard.GtgDealCardViewHa ndler has injected fields but has no injected constructor, and no public default constructor. Toothpick can't create a factory for it. SUPPRESS WARNING

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SUPPRESS WARNING class B$$Factory implements Factory { public B createInstance(Scope scope) { scope = getTargetScope(scope); B b = new B(); memberInjector.inject(b, scope); return b; } } class B$$MemberInjector implements MI { public B inject(B b, Scope scope) { b.d = scope.getInstance(D.class); b.e = scope.getInstance(E.class); } } public class B extends Fragment { @Inject D d; @Inject E e; private B(F f) { Toothpick.inject(this, scope); } }

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SUPPRESS WARNING class B$$Factory implements Factory { public B createInstance(Scope scope) { scope = getTargetScope(scope); B b = new B(); memberInjector.inject(b, scope); return b; } } class B$$MemberInjector implements MI { public B inject(B b, Scope scope) { b.d = scope.getInstance(D.class); b.e = scope.getInstance(E.class); } } X public class B extends Fragment { @Inject D d; @Inject E e; private B(F f) { Toothpick.inject(this, scope); } }

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SUPPRESS WARNING @SuppressWarnings(“injectable”) public class B extends Fragment { @Inject D d; @Inject E e; private B(F f) { Toothpick.inject(this, scope); } } class B$$MemberInjector implements MI { public B inject(B b, Scope scope) { b.d = scope.getInstance(D.class); b.e = scope.getInstance(E.class); } } D B E DI root

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UNIT TESTING public class B extends Fragment { @Inject D d; @Inject E e; public B() { Toothpick.inject(this, scope); } } D B E G

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UNIT TESTING public class B extends Fragment { @Inject D d; @Inject E e; public B() { Toothpick.inject(this, scope); } } MOCK ALL YOUR DEPENDENCIES

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UNIT TESTING public class B extends Fragment { @Inject D d; @Inject E e; public B() { Toothpick.inject(this, scope); } } MOCK ALL YOUR DEPENDENCIES public class BTest extends EasyMockSupport { @Rule public EasyMockRule easyMockRule; @Rule public ToothpickRule toothpickRule; @Mock D d; @Mock E e; }

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public class BTest extends EasyMockSupport { @Rule public EasyMockRule easyMockRule; @Rule public ToothpickRule toothpickRule; @Mock D d; @Mock E e; } UNIT TESTING D B E D B E G

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BAD PRACTICES 1. DO NOT USE ACTIVITY SCOPE AFTER ONDESTROY 2. DO NOT CALL LAZY.GET() AFTER ONDESTROY IF INJECTED USING ACTIVITY SCOPE 3. DO NOT OPEN SCOPE USING CONTEXT: CONTEXTSCOPEFINDER 4. USE SUPPRESSWARNING FOR DI ROOTS 5. MOCK ALL YOUR DEPENDENCIES

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BAD PRACTICES AND NICE TRICKS " TOOTHPICK