Toothpick Bad Practices 🙅 and Nice Tricks 👌

Presentation to improve Toothpick usage at Groupon

Transcript

1. BAD PRACTICES AND NICE TRICKS " TOOTHPICK
2. 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
3. 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
4. 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 WHAT???? WHY???? WHY???? WHAT????
5. SCOPE 1. TP INJECT TP # inject A
6. SCOPE 1. TP INJECT TP # inject A SCOPE 2. TP USES SCOPE TO INJECT
7. SCOPE 1. TP INJECT TP # inject A SCOPE 2. TP USES SCOPE TO INJECT
8. SCOPE MAKES THE INJECTIONS SCOPE
9. INJECTING STUFF: GRAPH AND ROOT A D B C E F G
10. 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
11. 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
12. 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
13. 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); } }
14. 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); } }
15. 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); } }
16. 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); } }
17. 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); } }
18. 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); } }
19. 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); } }
20. 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); ... } FACTORIES & MEMBER INJECTORS
21. SCOPE LIFECYCLE APPLICATION
 SCOPE
22. SCOPE LIFECYCLE APPLICATION
 SCOPE ACTIVITY
 SCOPE
23. SCOPE LIFECYCLE APPLICATION
 SCOPE
24. 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
25. 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 Crash CLOSED SCOPES CANNOT BE USED
26. SCOPE LIFECYCLE Crash DO NOT USE ACTIVITY SCOPE AFTER ONDESTROY CALLBACKS NETWORK CODE RX ASYNC CODE EVENT BUS LISTENERS
27. SCOPE LIFECYCLE
28. LAZIES & SCOPES %
29. public class A extends Activity { @Inject Lazy<B> 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(); } LAZIES & SCOPES LAZY<B> ACTIVITY
 SCOPE
30. public class A extends Activity { @Inject Lazy<B> 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(); } LAZIES & SCOPES LAZY<B> ACTIVITY
 SCOPE Crash
31. public class A extends Activity { @Inject Lazy<B> 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> 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<B> ACTIVITY
 SCOPE APPLICATION SCOPE
32. APPLICATION
 SCOPE ACTIVITY
 SCOPE APP SINGLETONS ACTIVITY SINGLETONS LAZIES & SCOPES
33. FACTORIES & MEMBER INJECTORS A D B C E F G @Singleton Lazy
34. FACTORIES & MEMBER INJECTORS A D B C E F G @Singleton ACTIVITY SCOPE Lazy
35. FACTORIES & MEMBER INJECTORS A D B C E F G @Singleton ACTIVITY SCOPE APPLICATION SCOPE Lazy
36. Crash DO NOT USE LAZY.GET() AFTER ONDESTROY CALLBACKS NETWORK CODE RX ASYNC CODE LAZIES & SCOPES EVENT BUS LISTENERS
37. LAZIES & SCOPES
38. 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
39. 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
40. 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
41. 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
42. 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
43. 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); } }
44. 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); } }
45. 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
46. UNIT TESTING public class B extends Fragment { @Inject D d; @Inject E e; public B() { Toothpick.inject(this, scope); } } D B E G
47. UNIT TESTING public class B extends Fragment { @Inject D d; @Inject E e; public B() { Toothpick.inject(this, scope); } } MOCK ALL YOUR DEPENDENCIES
48. 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; }
49. 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
50. 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
51. BAD PRACTICES AND NICE TRICKS " TOOTHPICK