Lessons From a Librarian

Transcript

1. Photo by Gabriel Sollmann on Unsplash Lessons From a Librarian James Barr - @JBarr21 Zac Sweers - @ZacSweers
2. subscribe()
3. subscribe(new Consumer<String>() { @Override public void accept(String value) { // Do stuff } })
4. subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } })
5. subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } })
6. subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } })
7. subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } })
8. subscribe(value -> { // Do stuff })
9. subscribe(value -> { // Do stuff }) github.com/uber/rxdogtag
10. subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(value -> { // Do stuff })
11. subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(value -> { // Do stuff })
12. subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(new CrashOnErrorConsumer<String>() { @Override public void accept(String value) { // Do stuff } }) subscribe(value -> { // Do stuff }) And thousands more
13. subscribe(value -> { // Do stuff }) subscribe(value -> { // Do stuff }) subscribe(value -> { // Do stuff }) subscribe(value -> { // Do stuff }) subscribe(value -> { // Do stuff }) subscribe(value -> { // Do stuff }) subscribe(value -> { // Do stuff }) subscribe(value -> { // Do stuff }) subscribe(value -> { // Do stuff }) subscribe(value -> { // Do stuff }) subscribe(value -> { // Do stuff }) subscribe(value -> { // Do stuff }) subscribe(value -> { // Do stuff })
14. - Anonymous audience member "But how?!"
15. Lessons from a Librarian
16. "Writing Code That Lasts Forever" - Jesse Wilson - Droidcon NYC 2018
17. Writing Code That Lasts Forever
18. Helping Everyone Write Code That Lasts Forever
19. Codebase Health ✅ Builds quickly ✅ Test coverage ✅ Well documented ❌ Duplicate code ❌ Deprecated APIs ❌ Large modules/classes
20. Name Build Time Undocumented Public Methods Module Size Deprecated Method Calls Quality Score (Overall: 75%) app 5m25s 0 10,000 LOC 0 75% feature1 4m20s 0 120,000 LOC 0 50% feature2 20s 0 4,000 LOC 0 100% library1 7s 90 1,000 LOC 0 75% library2 5s 0 2,000 LOC 88 75% Codebase Health
21. Name Build Time Undocumented Public Methods Module Size Deprecated Method Calls Quality Score (Overall: 75%) app 5m25s 0 10,000 LOC 0 75% feature1 4m20s 0 120,000 LOC 0 50% feature2 20s 0 4,000 LOC 0 100% library1 7s 90 1,000 LOC 0 75% library2 5s 0 2,000 LOC 88 75% Codebase Health
22. How does tech debt happen?
23. API Design
24. Limit Surface Area
25. Limit Surface Area class Hammer { public void hammer(Nail nail) { // ow } }
26. Limit Surface Area • Final by default final class Hammer { public void hammer(Nail nail) { // ow } }
27. Limit Surface Area • Final by default • Visibility final class Hammer { public void hammer(Nail nail) { // ow } }
28. Limit Surface Area • Final by default • Visibility • Factories final class Hammer { public static Hammer create() { // Stuff } private Hammer() { ... } }
29. Limit Surface Area final class Hammer { public void hammer(Nail nail) { // ow } } • Final by default • Visibility • Factories
30. API Design • Limit surface area • Final by default • Visibility • Factories • Consume interfaces interface Nail { void onHammer(); int length(); }
31. API Design • Limit surface area • Final by default • Visibility • Factories • Consume interfaces • Fluent APIs as navigation final class Hammer { public void removeNail(Nail nail) { // } }
32. API Design • Limit surface area • Final by default • Visibility • Factories • Consume interfaces • Fluent APIs as navigation final class Hammer { public RemovedNail removeNail(Nail nail) { // } }
33. API Design final class Hammer { public RemovedNail removeNail(Nail nail) { // } } hammer.removeNail() .dispose() • Limit surface area • Final by default • Visibility • Factories • Consume interfaces • Fluent APIs as navigation
34. API Design final class Hammer { public RemovedNail removeNail(Nail nail) { // } } hammer.removeNail() .dispose() • Limit surface area • Final by default • Visibility • Factories • Consume interfaces • Fluent APIs as navigation
35. - you, writing libraries "Does this put the user on the right track?"
36. - you, writing libraries "Does this put the user on the right track?" "Is this going to limit me later?"
37. API vs Implementation
38. API vs Implementation class Hammer { public void hammer(Nail nail) { // ow } }
39. API vs Implementation class Hammer { public void hammer(Nail nail) { // ow } } :hammer
40. API vs Implementation class Hammer { public void hammer(Nail nail) { // ow } } :hammer libA libA App
41. API vs Implementation class Hammer { public void hammer(Nail nail) { // ow } } :hammer libA libA App
42. API vs Implementation class Hammer { public void hammer(Nail nail) { // ow } } :hammer libA libA App
43. API vs Implementation class Hammer { public void hammer(Nail nail) { // ow } } :hammer libA libA App :hammer-api interface Hammer { void hammer(Nail nail) }
44. API vs Implementation class Hammer { public void hammer(Nail nail) { // ow } } :hammer libA libA App :hammer-api interface Hammer { void hammer(Nail nail) }
45. API vs Implementation class Hammer { public void hammer(Nail nail) { // ow } } :hammer libA libA App :hammer-api interface Hammer { void hammer(Nail nail) }
46. BuildConfig
47. BuildConfig public class BuildConfig { public static final String VERSION_NAME = "1.0"; public static final int VERSION_CODE = 1; public static final boolean DEBUG == false; }
48. BuildConfig public class BuildConfig { public static final String VERSION_NAME = "1.0"; public static final int VERSION_CODE = 1; public static final boolean DEBUG == false; } public interface AppBuildConfig { String versionName(); int versionCode(); boolean isDebug(); }
49. BuildConfig final class RealAppBuildConfig implements AppBuildConfig { // ... } public interface AppBuildConfig { String versionName(); int versionCode(); boolean isDebug(); } :appbuildconfig :app
50. BuildConfig final class RealAppBuildConfig implements AppBuildConfig { // ... } public interface AppBuildConfig { String versionName(); int versionCode(); boolean isDebug(); } :appbuildconfig :realappbuildconfig :app
51. BuildConfig final class RealAppBuildConfig implements AppBuildConfig { // ... } public interface AppBuildConfig { String versionName(); int versionCode(); boolean isDebug(); } :appbuildconfig :realappbuildconfig :app android { // or libraryVariants applicationVariants { generateBuildConfigProvider { enabled = true } } }
52. More Resources • API Design As An Art: youtube.com/watch?v=Ve9HlnJ0wCM • Writing Code That Lasts Forever: youtube.com/watch?v=YZstpc2939s • Effective Java • AppBuildConfig pattern: github.com/ZacSweers/CatchUp/pull/200
53. Code Review
54. Code Review Teach, don't tell
55. Code Review Approve with nits
56. Code Review
57. Static Analysis
58. Static Analysis
59. Static Analysis
60. Removing Tech Debt
61. Replace in Path (⌘⇧R) Find/Replace
62. Find/Replace Replace in Path (⌘⇧R) Command line tools > find . -name "*.java" | xargs sed -i '' “s/import foo/import barr/g”
63. Kotlin ReplaceWith class Example { fun foo(s: String) {a/* old */ } fun usage() { foo("hello") } }
64. Kotlin ReplaceWith class Example { @Deprecated("Use Example.bar") fun foo(s: String) { /* old */ } fun bar(s: String) { /* new */ } fun usage() { foo("hello") } }
65. Kotlin ReplaceWith class Example { @Deprecated("Use Example.bar", replaceWith = ReplaceWith(“bar(s)")) fun foo(s: String) { /* old */ } fun bar(s: String) { /* new */ } fun usage() { foo("hello") } }
66. Kotlin ReplaceWith class Example { @Deprecated("Use Example.bar", replaceWith = ReplaceWith(“bar(s)")) fun foo(s: String) { /* old */ } fun bar(s: String) { /* new */ } fun usage() { foo("hello") } }
67. Kotlin ReplaceWith class Example { @Deprecated("Use Example.bar", replaceWith = ReplaceWith(“bar(s)")) fun foo(s: String) { /* old */ } fun bar(s: String) { /* new */ } fun usage() { bar("hello") } }
68. import android.util.Pair fun doSomething() { val pair = Pair.create(“a”, “b”) } <FrameLayout android:layout_width="match_parent" android:layout_height="match_parent"> <FrameLayout android:layout_width="match_parent" android:layout_height="match_parent"> <View /> </FrameLayout> </FrameLayout> Android Lint SuggestedFix
69. import androidx.core.util.Pair fun doSomething() { val pair = Pair.create(“a”, “b”) } <FrameLayout android:layout_width="match_parent" android:layout_height="match_parent"> <FrameLayout android:layout_width="match_parent" android:layout_height="match_parent"> <View /> </FrameLayout> </FrameLayout> Android Lint SuggestedFix
70. Structural Find & Replace void main( Example ex, Other other) { ex.foo() ex.foo(“hi") other.foo() }
71. Structural Find & Replace void main( Example ex, Other other) { ex.foo() ex.foo(“hi") other.foo() } void main( Example ex, Other other) { ex.foo() ex.foo(“hi") other.foo() }
72. Structural Find & Replace void main( Example ex, Other other) { ex.foo() ex.foo(“hi") other.foo() } $Instance$ type=com.example.Example .foo($Parameter$ [0,∞]) $Instance$ type=com.example.Example .bar($Parameter$ [0,∞])
73. Structural Find & Replace void main( Example ex, Other other) { ex.bar() ex.bar(“hi") other.foo() } $Instance$ type=com.example.Example .foo($Parameter$ [0,∞]) $Instance$ type=com.example.Example .bar($Parameter$ [0,∞]) youtrack.jetbrains.com/issue/KT-10176
74. IntelliJ Plugin • Add your own refactor options • Leverage IntelliJ’s tools • Good for automating multiple uses of refactors https://cutt.ly/find-matches-action
75. Kotlin Script File(args[0]).walkTopDown() .filter { it.extension in setOf("java", "kt") } .filter { "/test/" !in it.absolutePath } .forEach {}
76. Kotlin Script File(args[0]).walkTopDown() .filter { it.extension in setOf("java", "kt") } .filter { "/test/" !in it.absolutePath } .forEach { file: File -> val fileLines = file.readLines().toMutableList() // modify lines of file file.writeText(fileLines.joinToString("\n")) }
77. Kotlin Script File(args[0]).walkTopDown() .filter { it.extension in setOf("java", "kt") } .filter { "/test/" !in it.absolutePath } .forEach { file: File -> val fileLines = file.readLines().toMutableList() // modify lines of file file.writeText(fileLines.joinToString("\n")) } $ brew install holgerbrandl/tap/kscript $ kscript MigrateToAndroidX.kts ~/project-root 16,866 files changed, 31,454 insertions(+), 31,415 deletions(-)
78. De-risking Change
79. Shadow Jobs
80. Shadow Jobs Android Gradle Plugin 4 beta/4.1 alpha Kotlin 1.4-M1 Gradle 6.4-rc -SNAPSHOT Androidx alphas JDK 8-14 Shadow Jobs
81. Offensive Programming
82. Offensive Programming abstract class Model { abstract List<String> modelList(); }
83. Offensive Programming abstract class Model { abstract ImmutableList<String> modelList(); }
84. Offensive Programming abstract class Model { abstract List<String> modelList(); } ImmutableList
85. b7cb262 - Migrate lib1 d43aa98 - Migrate lib2 a1dc8d1 - Migrate lib3 d843d8f - Migrate lib4 vs a13ab55 - Migrate all libs Safety Without Feature Flags
86. Photo by Webaroo on Unsplash
87. Photo by Pankaj Patel on Unsplash
88. Photo by Margarida CSilva on Unsplash
89. Photo by Hannes Wolf on Unsplash
90. Wrap Up
91. Photo by Gabriel Sollmann on Unsplash Lessons From a Librarian James Barr - @JBarr21 Zac Sweers - @ZacSweers