Code Generation for Fun & Profit (Swift Edition)

Presented in April '17 Swift Delhi meetup.
https://www.meetup.com/Swift-Delhi/events/239248482/

Transcript

1. Code Generation for Fun & Profit (Swift Edition) Ragunath Jawahar
2. A mobile app developer walks into the bar…
3. A mobile app developer walks into the bar office…
5. Tracking Code (Swift) let properties  = [ "Gender": "Female", "Logged  in": false, "Source": "Twitter" ] Mixpanel.mainInstance() .track(event: "Signup", properties: properties)
6. Tracking Code (Swift) let properties  = [ "Gender": "Female", "Logged  in": false, "Source": "Twitter" ] Mixpanel.mainInstance() .track(event:  "Signup",  properties:  properties)
7. Tracking Code (Swift) let  properties  =  [ "Gender":  "Female", "Logged  in":  false, "Source":  "Twitter" ] Mixpanel.mainInstance() .track(event: "Signup", properties: properties)
8. Tracking Code (Java) MixpanelAPI mixpanel = MixpanelAPI.getInstance(this, token); try { JSONObject payload  = new JSONObject(); payload.put("Gender", "Female"); payload.put("Logged  in", false); payload.put("Source", "Twitter"); mixpanel.track("Signup", payload); } catch (JSONException exception) { Log.e("Frodo", "JsonException", exception); }
9. Tracking Code (Java) MixpanelAPI mixpanel = MixpanelAPI.getInstance(this, token); try  { JSONObject payload  =  new  JSONObject(); payload.put("Gender",  "Female"); payload.put("Logged  in",  false); payload.put("Source",  "Twitter"); mixpanel.track("Signup",  payload); }  catch  (JSONException exception)  { Log.e("Frodo",  "JsonException",  exception); }
10. Tracking Code (Java) MixpanelAPI mixpanel =  MixpanelAPI.getInstance(this,  token); try  { JSONObject payload  = new JSONObject(); payload.put("Gender", "Female"); payload.put("Logged  in", false); payload.put("Source", "Twitter"); mixpanel.track("Signup",  payload); }  catch  (JSONException exception)  { Log.e("Frodo",  "JsonException",  exception); }
11. Tracking Code (Java) MixpanelAPI mixpanel =  MixpanelAPI.getInstance(this,  token); try  { JSONObject payload  =  new  JSONObject(); payload.put("Gender",  "Female"); payload.put("Logged  in",  false); payload.put("Source",  "Twitter"); mixpanel.track("Signup", payload); }  catch  (JSONException exception)  { Log.e("Frodo",  "JsonException",  exception); }
12. GREMLINS
15. …and only 300 more rows
16. MAY THE “BRUTE” FORCE BE WITH YOU
17. Problems •Slow •Boring •Inaccurate •Error Prone •Hard to Test •Difficult to Change •Multiple Platforms •Multiple Apps
18. Requirements • Accuracy • Accommodate Changes • Don’t Leak Cognitive Resources • Testability • Support Multiple Apps and Platforms
20. WORKFLOW – SCREEN – EVENT
21. workflow().screen().event()
22. SOLVING MYSTERY
23. Java Poet – Method MethodSpec mainMethod = MethodSpec.methodBuilder("main") .addModifiers(Modifier.PUBLIC, Modifier.STATIC) .addParameter(String[].class, "args") .addStatement( "$T.out.println($S)", System.class, "Hello,  World!” ).build();
24. Java Poet – Method MethodSpec mainMethod =  MethodSpec.methodBuilder("main") .addModifiers(Modifier.PUBLIC,  Modifier.STATIC) .addParameter(String[].class,  "args") .addStatement( "$T.out.println($S)", System.class, "Hello,  World!” ).build();
25. Java Poet – Method MethodSpec mainMethod =  MethodSpec.methodBuilder("main") .addModifiers(Modifier.PUBLIC, Modifier.STATIC) .addParameter(String[].class,  "args") .addStatement( "$T.out.println($S)", System.class, "Hello,  World!” ).build();
26. Java Poet – Method MethodSpec mainMethod =  MethodSpec.methodBuilder("main") .addModifiers(Modifier.PUBLIC,  Modifier.STATIC) .addParameter(String[].class, "args") .addStatement( "$T.out.println($S)", System.class, "Hello,  World!” ).build();
27. Java Poet – Method MethodSpec mainMethod =  MethodSpec.methodBuilder("main") .addModifiers(Modifier.PUBLIC,  Modifier.STATIC) .addParameter(String[].class,  "args") .addStatement( "$T.out.println($S)", System.class, "Hello,  World!” ).build();
28. Java Poet – Method MethodSpec mainMethod =  MethodSpec.methodBuilder("main") .addModifiers(Modifier.PUBLIC,  Modifier.STATIC) .addParameter(String[].class,  "args") .addStatement( "$T.out.println($S)", System.class, "Hello,  World!” ).build();
29. Java Poet – Class TypeSpec greeterClass = TypeSpec.classBuilder("Greeter") .addModifiers(Modifier.PUBLIC) .addMethod(mainMethod) .build();
30. Java Poet – Class TypeSpec greeterClass =  TypeSpec.classBuilder("Greeter") .addModifiers(Modifier.PUBLIC) .addMethod(mainMethod) .build();
31. Java Poet – Class TypeSpec greeterClass =  TypeSpec.classBuilder("Greeter") .addModifiers(Modifier.PUBLIC) .addMethod(mainMethod) .build();
32. Java Poet – Class TypeSpec greeterClass =  TypeSpec.classBuilder("Greeter") .addModifiers(Modifier.PUBLIC) .addMethod(mainMethod) .build();
33. Java Poet – Class TypeSpec greeterClass =  TypeSpec.classBuilder("Greeter") .addModifiers(Modifier.PUBLIC) .addMethod(mainMethod) .build();
34. Java Poet – Compilation Unit JavaFile greeterFile = JavaFile.builder("in.kitecash", greeterClass).build(); greeterFile.writeTo(System.out);
35. Java Poet – Compilation Unit JavaFile greeterFile =  JavaFile.builder("in.kitecash", greeterClass).build(); greeterFile.writeTo(System.out);
36. Java Poet – Compilation Unit JavaFile greeterFile =  JavaFile.builder("in.kitecash", greeterClass).build(); greeterFile.writeTo(System.out);
37. Java Poet – Compilation Unit JavaFile greeterFile =  JavaFile.builder("in.kitecash", greeterClass).build(); greeterFile.writeTo(System.out);
38. Java Poet – Generated Class package in.kitecash; import java.lang.String; import java.lang.System; public class Greeter { public static void main(String[] args) { System.out.println("Hello,  World!"); } }
39. BLUEPRINT
40. Objective workflow().screen().event()
41. ITERATE ON PAPER
42. Components •CSV Parser •Source Code Generator
43. High-Level Design •Generated abstract Tracker class •Generated Analytics class •Generated Workflow classes •Generated Screen inner classes
44. Class Diagram …  more  workflow  classes
45. Class Diagram …  more  inner  screen  classes
46. Tracker public abstract class Tracker { public  abstract  void track(String event, Map<String, String> payload); }
47. Tracker public  abstract  class  Tracker  { public  abstract  void track(String event, Map<String, String> payload); }
48. Tracker public  abstract  class  Tracker  { public  abstract  void  track(String event, Map<String,  String>  payload); }
49. Tracker public  abstract  class  Tracker  { public  abstract  void  track(String  event, Map<String, String> payload); }
50. Analytics •Instantiated  by  supplying  a  Tracker implementation •Entry-­‐point  to  event  tracking
51. workflow().screen().event() •Generated as top-level classes •Encapsulates screen inner classes
52. workflow().screen().event() •Workflow inner classes •Encapsulates event tracking methods
53. workflow().screen().event() •Event tracking methods •Resides inside screen classes •May accept parameters for collecting additional data
54. ACCURACY
55. WRITE CODE TO GENERATE CODE
56. WRITE CODE TO GENERATE CODE
57. CHANGES
58. CSV Removals – Red Markers
59. CSV Removals – Red Markers
60. CSV Additions – Gray Methods
61. CSV Additions – Gray Methods
62. PRODUCTIVITY
63. Auto-Completion
64. Auto-Completion
65. Checklist
66. Checklist
67. Checklist
68. Checklist
69. Checklist
70. Checklist
71. Checklist
72. TESTING
73. HOW? •Schemes (iOS) & Product Flavors (Android) •Dependency Injection
74. Trackers •Log Tracker •Mixpanel Tracker •Dialog Tracker •Verifying Tracker
75. iOS + Swift
76. DIFFICULTIES •Swift •No Transpilers •No Code Generation Libraries
77. J2ObjC
78. J2ObjC Java Objective-C Swift
79. J2ObjC Java Objective-C Swift
80. J2ObjC Java Objective-C Swift
81. PEACE
82. PEACE
83. abstract  class(es) NOT interface(s)
84. J2ObjC NUANCES •Runtime Library •Adds ~10 MB
85. CODE GENERATION TIPS • Doesn’t have to be DRY • Iterate through the design several times • Add “Auto-Generated” comments and documentation • Prefer abstract classes over interfaces • Extract platform-specific code and provide abstraction • Communicate with Business Intelligence team
86. ragunathjawahar GitHub / Twitter / Speakerdeck