Dependency Inversion from S to D (SOLID)

Made together with this awesome developer, https://speakerdeck.com/cdmunoz.

Solid introduction talk to explain why abstractions, encapsulation and OO concepts works together to build better software.

https://www.youtube.com/watch?v=gy2i5GSxqXA

Transcript

1. Inversión de dependencias de la S a la D (SOLID) @cdmunozi
 @danielgomezrico
2. Mundo Real
4. 
 
 Object Oriented Programming Encapsulation Polymorphism Inheritance Data Abstraction Class Objects
5. Encapsulation
6. Encapsulation
8. Ejemplo login cochino
9. Ejemplo práctico
10. data class Person(val name: string) val person = Person("Juanito") print(person.name)
11. 11 data class User( val email: String, val name: String, val id: String ) interface LoginService { @POST("login") fun login(@Query("email") email: String?, @Query("password") password: String?) : Call<User>? } class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) findViewById<Button>(R.id.login_button).setOnClickListener { val progressBar = findViewById<View>(R.id.login_progress).apply { visibility = View.VISIBLE } val email = findViewById<EditText>(R.id.login_email).text.toString() val password = findViewById<EditText>(R.id.login_password).text.toString() val retrofit = Retrofit.Builder() .client(OkHttpClient.Builder() .addInterceptor( HttpLoggingInterceptor().apply { level = (HttpLoggingInterceptor.Level.BODY) } ).build() ) .baseUrl("https://602db10196eaad00176dcb6d.mockapi.io") .addConverterFactory(MoshiConverterFactory.create()) .build() val service: LoginService = retrofit.create(LoginService::class.java) val call = service.login(email, password) call?.enqueue(object : Callback<User> { override fun onResponse(call: Call<User>, response: Response<User>) { progressBar.visibility = View.GONE if (response.isSuccessful) { val user = response.body() AlertDialog.Builder(this@MainActivity) .setTitle("Hola!") .setMessage("Bienvenido ${user?.name ?: ""}!") .setPositiveButton(android.R.string.yes, null) .setNegativeButton(android.R.string.no, null) .show() } else { https://github.com/ MedellinAndroid/ dependency_inversion_example
12. LoginActivity login_activity.xml Android Lifecycle (onCreate, ...) Android View Elements (Button, TextField, etc...) HTTP Client Third Party API Service Response/Request serialization (JSON, XML, ...) HTTP Error handling HTTP Status Code UserModel Logica
13. 1. Qué hace actualmente el MainActivity? - Cuál debería ser su responsabilidad? 2. Qué sucede si quiero hacer tests? 3. Qué sucede si quiero hacer login desde multiples vistas? 4. Si llega alguien nuevo al equipo (o se va...) 5. Cuál debería ser su responsabilidad? 6. Qué sucede si quiero agregar login social (google, fb, etc)? 7. Qué pasa si para desarrollar queremos tener logs para todos los requests? 8. Dónde vamos a guardar al usuario logeado? SharedPreferences? Room?
14. Book: "The Art of Readable Code"
15. Inversion de dependencias
16. Ejemplo login con repositorio
17. 17 data class User( val email: String, val name: String, val id: String ) interface LoginService { @POST("login") fun login(@Query("email") email: String?, @Query("password") password: String?) : Call<User>? } class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) findViewById<Button>(R.id.login_button).setOnClickListener { val progressBar = findViewById<View>(R.id.login_progress).apply { visibility = View.VISIBLE } val email = findViewById<EditText>(R.id.login_email).text.toString() val password = findViewById<EditText>(R.id.login_password).text.toString() val retrofit = Retrofit.Builder() .client(OkHttpClient.Builder() .addInterceptor( HttpLoggingInterceptor().apply { level = (HttpLoggingInterceptor.Level.BODY) } ).build() ) .baseUrl("https://602db10196eaad00176dcb6d.mockapi.io") .addConverterFactory(MoshiConverterFactory.create()) .build() val service: LoginService = retrofit.create(LoginService::class.java) val call = service.login(email, password) call?.enqueue(object : Callback<User> { override fun onResponse(call: Call<User>, response: Response<User>) { progressBar.visibility = View.GONE if (response.isSuccessful) { val user = response.body() AlertDialog.Builder(this@MainActivity) .setTitle("Hola!") .setMessage("Bienvenido ${user?.name ?: ""}!") .setPositiveButton(android.R.string.yes, null) .setNegativeButton(android.R.string.no, null) .show() } else {
18. LoginActivity login_activity.xml Android Lifecycle (onCreate, ...) Android View Elements (Button, TextField, etc...) HTTP Client Third Party API Service Response/Request serialization (JSON, XML, ...) HTTP Error handling HTTP Status Code UserModel Logica
19. The Magical Mystery Four: How is Working Memory Capacity Limited, and Why? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2864034/ Working memory storage capacity is important because cognitive tasks can be completed only with su ff i cient ability to hold information as it is processed. The ability to repeat information depends on task demands but can be distinguished from a more constant, underlying mechanism: a central memory store limited to 3 to 5 meaningful items in young adults. [...] The Magical Mystery Four: How is Working Memory Capacity Limited, and Why?
20. LoginActivity login_activity.xml Android Lifecycle (onCreate, ...) Android View Elements (Button, TextField, etc...) HTTP Client Third Party API Service Response/Request serialization (JSON, XML, ...) HTTP Error handling HTTP Status Code UserModel Logica
21. UserRepository LoginActivity login_activity.xml Android Lifecycle (onCreate, ...) Android View Elements (Button, TextField, etc...) HTTP Client Third Party API Service Response/Request serialization (JSON, XML, ...) HTTP Error handling HTTP Status Code UserModel Logica
22. UserRepository HTTP Client Third Party API Service Response/Request serialization (JSON, XML, ...) HTTP Error handling HTTP Status Code
23. class UserRepository { private val service: LoginService init { val retrofit = Retrofit.Builder() .client( OkHttpClient.Builder() .addInterceptor( HttpLoggingInterceptor().apply { level = (HttpLoggingInterceptor.Level.BODY) } ).build() ) .baseUrl("https://602db10196eaad00176dcb6d.mockapi.io") .addConverterFactory(MoshiConverterFactory.create()) .build() service = retrofit.create(LoginService::class.java) } fun login(email: String, password: String, responseCallback: (User?) -> Unit) { val call = service.login(email, password) call?.enqueue(object : Callback<User> { override fun onResponse(call: Call<User>, response: Response<User>) { if (response.isSuccessful) { val user = response.body() responseCallback(user) } else { responseCallback(null) } } override fun onFailure(call: Call<User>, t: Throwable) { responseCallback(null) } }) } }
24. UserRepository HTTP Client Third Party API Service Response/Request serialization (JSON, XML, ...) HTTP Error handling HTTP Status Code
25. Service UserRepository HTTP Client Third Party API Service Response/Request serialization (JSON, XML, ...) HTTP Error handling HTTP Status Code
26. class UserRepository { private val service: LoginService init { val retrofit = Retrofit.Builder() .client( OkHttpClient.Builder() .addInterceptor( HttpLoggingInterceptor().apply { level = (HttpLoggingInterceptor.Level.BODY) } ).build() ) .baseUrl("https://602db10196eaad00176dcb6d.mockapi.io") .addConverterFactory(MoshiConverterFactory.create()) .build() service = retrofit.create(LoginService::class.java) } fun login(email: String, password: String, responseCallback: (User?) -> Unit) { val call = service.login(email, password) call?.enqueue(object : Callback<User> { override fun onResponse(call: Call<User>, response: Response<User>) { if (response.isSuccessful) { val user = response.body() responseCallback(user) } else { responseCallback(null) } } override fun onFailure(call: Call<User>, t: Throwable) { responseCallback(null) } }) } }
27. class UserRepository(private val service: LoginService) { private val service: LoginService init { val retrofit = Retrofit.Builder() .client( OkHttpClient.Builder() .addInterceptor( HttpLoggingInterceptor().apply { level = (HttpLoggingInterceptor.Level.BODY) } ).build() ) .baseUrl("https://602db10196eaad00176dcb6d.mockapi.io") .addConverterFactory(MoshiConverterFactory.create()) .build() service = retrofit.create(LoginService::class.java) } fun login(email: String, password: String, responseCallback: (User?) -> Unit) { val call = service.login(email, password) call?.enqueue(object : Callback<User> { override fun onResponse(call: Call<User>, response: Response<User>) { if (response.isSuccessful) { val user = response.body() responseCallback(user) } else { responseCallback(null) } } override fun onFailure(call: Call<User>, t: Throwable) { responseCallback(null) } }) } }
28. class UserRepository(private val service: LoginService) { fun login(email: String, password: String, responseCallback: (User?) -> Unit) { val call = service.login(email, password) call?.enqueue(object : Callback<User> { override fun onResponse(call: Call<User>, response: Response<User>) { if (response.isSuccessful) { val user = response.body() responseCallback(user) } else { responseCallback(null) } } override fun onFailure(call: Call<User>, t: Throwable) { responseCallback(null) } }) } }
29. class Api { fun buildUserRepository(): UserRepository { val retrofit = Retrofit.Builder() .client( OkHttpClient.Builder() .addInterceptor( HttpLoggingInterceptor().apply { level = (HttpLoggingInterceptor.Level.BODY) } ).build() ) .baseUrl("https://602db10196eaad00176dcb6d.mockapi.io") .addConverterFactory(MoshiConverterFactory.create()) .build() val service: LoginService = retrofit.create(LoginService::class.java) return UserRepository(service) } }
30. class Api { fun buildUserRepository(): UserRepository { val retrofit = Retrofit.Builder() .client( OkHttpClient.Builder() .addInterceptor( HttpLoggingInterceptor().apply { level = (HttpLoggingInterceptor.Level.BODY) } ).build() ) .baseUrl("https://602db10196eaad00176dcb6d.mockapi.io") .addConverterFactory(MoshiConverterFactory.create()) .build() val service: LoginService = retrofit.create(LoginService::class.java) return UserRepository(service) } }
31. class Api { fun buildUserRepository(): UserRepository { val retrofit = Retrofit.Builder() .client( OkHttpClient.Builder() .addInterceptor( HttpLoggingInterceptor().apply { level = (HttpLoggingInterceptor.Level.BODY) } ).build() ) .baseUrl("https://602db10196eaad00176dcb6d.mockapi.io") .addConverterFactory(MoshiConverterFactory.create()) .build() val service: LoginService = retrofit.create(LoginService::class.java) return UserRepository(service) } } class UserRepository(private val service: LoginService) { fun login(email: String, password: String, responseCallback: (User?) -> Unit) { val call = service.login(email, password) call?.enqueue(object : Callback<User> { override fun onResponse(call: Call<User>, response: Response<User>) { if (response.isSuccessful) { val user = response.body() responseCallback(user) } else { responseCallback(null) } } override fun onFailure(call: Call<User>, t: Throwable) { responseCallback(null) } }) } }
32. class Api { fun buildUserRepository(): UserRepository { val retrofit = Retrofit.Builder() .client( OkHttpClient.Builder() .addInterceptor( HttpLoggingInterceptor().apply { level = (HttpLoggingInterceptor.Level.BODY) } ).build() ) .baseUrl("https://602db10196eaad00176dcb6d.mockapi.io") .addConverterFactory(MoshiConverterFactory.create()) .build() val service: LoginService = retrofit.create(LoginService::class.java) return UserRepository(service) } } class UserRepository(private val service: LoginService) { fun login(email: String, password: String, responseCallback: (User?) -> Unit) { val call = service.login(email, password) call?.enqueue(object : Callback<User> { override fun onResponse(call: Call<User>, response: Response<User>) { if (response.isSuccessful) { val user = response.body() responseCallback(user) } else { responseCallback(null) } } override fun onFailure(call: Call<User>, t: Throwable) { responseCallback(null) } }) } }
33. 33 data class User( val email: String, val name: String, val id: String ) interface LoginService { @POST("login") fun login(@Query("email") email: String?, @Query("password") password: String?) : Call<User>? } class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) findViewById<Button>(R.id.login_button).setOnClickListener { val progressBar = findViewById<View>(R.id.login_progress).apply { visibility = View.VISIBLE } val email = findViewById<EditText>(R.id.login_email).text.toString() val password = findViewById<EditText>(R.id.login_password).text.toString() val retrofit = Retrofit.Builder() .client(OkHttpClient.Builder() .addInterceptor( HttpLoggingInterceptor().apply { level = (HttpLoggingInterceptor.Level.BODY) } ).build() ) .baseUrl("https://602db10196eaad00176dcb6d.mockapi.io") .addConverterFactory(MoshiConverterFactory.create()) .build() val service: LoginService = retrofit.create(LoginService::class.java) val call = service.login(email, password) call?.enqueue(object : Callback<User> { override fun onResponse(call: Call<User>, response: Response<User>) { progressBar.visibility = View.GONE if (response.isSuccessful) { val user = response.body() AlertDialog.Builder(this@MainActivity) .setTitle("Hola!") .setMessage("Bienvenido ${user?.name ?: ""}!") .setPositiveButton(android.R.string.yes, null) .setNegativeButton(android.R.string.no, null) .show() } else {
34. class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) findViewById<Button>(R.id.login_button).setOnClickListener { val progressBar = findViewById<View>(R.id.login_progress).apply { visibility = View.VISIBLE } val email = findViewById<EditText>(R.id.login_email).text.toString() val password = findViewById<EditText>(R.id.login_password).text.toString() val userRepository = Api().buildUserRepository() userRepository.login(email, password) { progressBar.visibility = View.GONE if (it != null) { AlertDialog.Builder(this@MainActivity) .setTitle("Hola!") .setMessage("Bienvenido ${it.name}!") .setPositiveButton(android.R.string.yes, null) .setNegativeButton(android.R.string.no, null) .show() } else { AlertDialog.Builder(this@MainActivity) .setTitle("Error!") .setMessage("Algo paso 1!") .setPositiveButton(android.R.string.yes, null) .setNegativeButton(android.R.string.no, null) .show() } } } } }
35. 35 data class User( val email: String, val name: String, val id: String ) interface LoginService { @POST("login") fun login(@Query("email") email: String?, @Query("password") password: String?) : Call<User>? } class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) findViewById<Button>(R.id.login_button).setOnClickListener { val progressBar = findViewById<View>(R.id.login_progress).apply { visibility = View.VISIBLE } val email = findViewById<EditText>(R.id.login_email).text.toString() val password = findViewById<EditText>(R.id.login_password).text.toString() val retrofit = Retrofit.Builder() .client(OkHttpClient.Builder() .addInterceptor( HttpLoggingInterceptor().apply { level = (HttpLoggingInterceptor.Level.BODY) } ).build() ) .baseUrl("https://602db10196eaad00176dcb6d.mockapi.io") .addConverterFactory(MoshiConverterFactory.create()) .build() val service: LoginService = retrofit.create(LoginService::class.java) val call = service.login(email, password) call?.enqueue(object : Callback<User> { override fun onResponse(call: Call<User>, response: Response<User>) { progressBar.visibility = View.GONE if (response.isSuccessful) { val user = response.body() AlertDialog.Builder(this@MainActivity) .setTitle("Hola!") .setMessage("Bienvenido ${user?.name ?: ""}!") .setPositiveButton(android.R.string.yes, null) .setNegativeButton(android.R.string.no, null) .show() } else { AlertDialog.Builder(this@MainActivity) .setTitle("Error!") .setMessage("Algo paso 1!") .setPositiveButton(android.R.string.yes, null) .setNegativeButton(android.R.string.no, null) .show() } } override fun onFailure(call: Call<User>, t: Throwable) { progressBar.visibility = View.GONE Log.e("Login", "Error", t) AlertDialog.Builder(this@MainActivity) class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) findViewById<Button>(R.id.login_button).setOnClickListener { val progressBar = findViewById<View>(R.id.login_progress).apply { visibility = View.VISIBLE } val email = findViewById<EditText>(R.id.login_email).text.toString() val password = findViewById<EditText>(R.id.login_password).text.toString() val userRepository = Api().buildUserRepository() userRepository.login(email, password) { progressBar.visibility = View.GONE if (it != null) { AlertDialog.Builder(this@MainActivity) .setTitle("Hola!") .setMessage("Bienvenido ${it.name}!") .setPositiveButton(android.R.string.yes, null) .setNegativeButton(android.R.string.no, null) .show() } else { AlertDialog.Builder(this@MainActivity) .setTitle("Error!") .setMessage("Algo paso 1!") .setPositiveButton(android.R.string.yes, null) .setNegativeButton(android.R.string.no, null) .show() } } } } }
36. LoginActivity login_activity.xml Android Lifecycle (onCreate, ...) Android View Elements (Button, TextField, etc...) HTTP Client Third Party API Service Response/Request serialization (JSON, XML, ...) HTTP Error handling HTTP Status Code UserModel Navigation SharedPreferences Logica
37. Service (ej retro fi t) UserRepository HTTP Client Third Party API Service Response/Request serialization (JSON, XML, ...) HTTP Error handling HTTP Status Code LoginActivity login_activity.xml Android Lifecycle (onCreate, ...) Android View Elements (Button, TextField, etc...) UserModel Logica
38. https://github.com/MedellinAndroid/dependency_inversion_example/pull/1
39. Ejemplo login con ViewModels/ Presenters
40. LoginActivity login_activity.xml Android Lifecycle (onCreate, ...) Android View Elements (Button, TextField, etc...) UserModel Navigation Logica
41. ViewModel/Presenter LoginActivity login_activity.xml Android Lifecycle (onCreate, ...) Android View Elements (Button, TextField, etc...) Navigation Logica UserModel
42. Coordinator Navigation ViewModel/Presenter LoginActivity login_activity.xml Android Lifecycle (onCreate, ...) Android View Elements (Button, TextField, etc...) Logica UserModel
43. Service (ej retro fi t) UserRepository HTTP Client Third Party API Service Response/Request serialization (JSON, XML, ...) HTTP Error handling HTTP Status Code Coordinator Navigation ViewModel/Presenter LoginActivity login_activity.xml Android Lifecycle (onCreate, ...) Android View Elements (Button, TextField, etc...) Logica UserModel
44. LoginActivity login_activity.xml Android Lifecycle (onCreate, ...) Android View Elements (Button, TextField, etc...) HTTP Client Third Party API Service Response/Request serialization (JSON, XML, ...) HTTP Error handling HTTP Status Code UserModel Navigation SharedPreferences Logica
45. Service (ej retro fi t) UserRepository HTTP Client Third Party API Service Response/Request serialization (JSON, XML, ...) HTTP Error handling HTTP Status Code Coordinator Navigation ViewModel/Presenter LoginActivity login_activity.xml Android Lifecycle (onCreate, ...) Android View Elements (Button, TextField, etc...) Logica UserModel
46. Conclusiones
47. Gracias
48. Repository - Base: https://github.com/MedellinAndroid/dependency_inversion_example - With repositories: https://github.com/MedellinAndroid/ dependency_inversion_example/pull/1 - Software is details - Kevlin Henney: https://www.youtube.com/watch? v=kX0prJklhUE - Wikipedia: https://en.wikipedia.org/wiki/Dependency_inversion_principle - Imagenes: https://www.clarisoft.com/best-proven-method-scale-software-development- team/ https://developer.android.com/images/teach/hero.svg Referencias