Migrate from RoboGuice 4 to Toothpick

Internal workshop at groupon

Transcript

1. Migrate to TP
   form RG 4..
   https://github.com/stephanenicolas/toothpick/wiki
   

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2. Toothpick is a scope tree based Dependency
   Injection (DI) library for Java.
   It is a full-featured, runtime based, 

   but reflection free, implementation of JSR 330.
   Toothpick is faster than Dagger 1 or Dagger 2

   for a relatively small number of injections (<1K)
   2
   

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3. Presentation plan
   1. TP  scopes  
   2. Injec/ng  all  dependencies  into  an  object  
   3. Ge9ng  an  instance/lazy/provider  of  a  class  
   4. Named  injec/ons    
   5. Lazies    
   6. ContextSingleton  and  why  you  should  not  use  it    
   7. Tes/ng  &  Mock
   Migrate to TP
   

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4. TP scopes
   In  Toothpick,  scopes  are:    
   • a  place  to  define  bindings  (via  modules)  
   • a  place  to  recycle  injected  instances  
   Scopes  are  used  to:    
   • inject  dependencies  into  instances  
   • getInstance  of  classes
   Migrate to TP
   

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5. TP scope tree
   It’s a common practice to define a scope by context. In advanced uses
   cases, more scopes can be created. Scopes form a tree.
   Migrate to TP
   

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6. Before: RG.getInjector
   TP scopes are similar to injector in RG.

   In MGA, this is managed by the foundations classes.
   Migrate to TP
   

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7. openScope(s) methods need “the name” of the scope as a parameter. 

   If multiple scopes are open together, they form a hierarchy 

   and the leaf is returned.
   Opening and closing scopes in TP
   Migrate to TP
   

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8. Opening and closing scopes in TP
   Migrate to TP
   

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9. Installing modules in TP
   Modules are very similar in RG and TP. 

   The main difference is that TP doesn’t need a configure method, you
   can declare bindings directly in the constructor of the modules.
   Migrate to TP
   

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10. Injecting dependencies: RG 4
    Migrate to TP
    

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11. Injecting dependencies: TP
    Migrate to TP
    

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12. Getting instance of classes: RG 4
    This was equivalent to declare a field 

    @Inject ImageCacheWarmup imageCacheWarmup.
    RG would return a new instance or recycle a previous instance in the
    scope of the injector, depending on annotations of
    ImageCacheWarmup.
    Migrate to TP
    

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13. Getting instance of classes: TP
    Still equivalent to declare a field 

    @Inject ImageCacheWarmup imageCacheWarmup.
    TP will also return a new instance or recycle a previous instance in
    the scope of the injector, depending on annotations of
    ImageCacheWarmup.
    Migrate to TP
    

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14. Getting lazies/providers of classes: TP
    TP API also allows to easily get a provider or a lazy on a dependency.
    This is also equivalent to declaring a lazy / provider field.
    Migrate to TP
    

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15. Named injections
    Migrate to TP
    Named injections are simpler with TP. You don’t need to use Named.
    Before with RG
    After with TP
    

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16. Lazies: RG
    Migrate to TP
    You had to declared AND initialize Lazies with RG. 

    But it was pure boiler plate code.
    

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17. Lazies: TP
    Migrate to TP
    !!! TP makes Lazies simpler, just declare Lazies.
    Don’t forget to @Inject them !!!
    

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18. Avoid ContextSingleton
    Migrate to TP
    ContextSingleton is just NOT clear. 

    You can create a singleton at the app level or at the activity level, depending on
    where the injection first happens. This easily creates leaks !
    

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19. Use Singleton or ActivitySingleton
    Migrate to TP
    Try your best to either use a real app singleton (and only use the
    application there) 

    OR an ActivitySingleton (and use the activity as a context)
    

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20. Testing and mocking: RG
    Migrate to TP
    You can inject test dependencies or mock the dependencies needed
    under test…
    

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21. Testing and mocking: TP
    Migrate to TP
    Nothing changed (for now).
    But you don’t need to reset the mocks anymore (weird cases are solved).
    

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22. Conclusion
    Migrate to TP
    TP  is  just:  beVer,  easier,  faster  than  RG.    
    Dig into the TP wiki to get more insight on TP.
    TP   has   more   to   offer   than   RG:   scopes   spanning   mul/ple   ac/vi/es,   state  
    preserva/on  across  rota/ons,  etc.  We  will  slowly  use  these  features  in  the  app  
    over  next  releases…

    

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23. Questions ?
    Migrate to TP
    Comments ?
    

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