Super and Inner Together at Last!

Transcription

1 Super and Inner Together at Last! David S. Goldberg University of Utah Robert Bruce Findler University of Chicago Matthew Flatt University of Utah 1

2 Java-Style Method Overriding m() {... Class A new C().m() Class B m() {... super... Class C m() {... super... 2

3 Beta-Style Method Augmentation Class A m() {... inner... new C().m() Class B m() {... inner... m() {... Class C 3

4 A Combination m() {... Class A new C().m() Class B m() {... super inner... m() {... Class C 4

5 Creating a GUI Hierarchy Border Image Highlight 5

6 and Border in Java Border Image Highlight class... void { // paint the background:...; class Border... void { // paint background: super.; // draw a border:...; 6

7 in Java Border class... void { // paint background, border: super.; // draw a button label:...; Image Highlight 7

8 Image in Java Border Image Highlight class Image... void { // paints background, border // - and label! super.; // draw image // must cover label:...; 8

9 Fixed Border and in Java Border paintinside() paintinside() class Border... final void { // paint background: super.; // paint a border:...; paintinside(); void paintinside() { Image paintinside() Highlight paintinside() class... void paintinside() { // draw label:...; 9

10 Image and Highlight in Java Image Border paintinside() paintinside() paintinside() Highlight paintinside() class Image... void paintinside() { // draws image // doesn't call super // for label:...; class Highlight... void paintinside() { // replace background with // blue gradient:...; // draws the label: super.paintinside(); 10

11 The Problem with Inventing Names Border Image Highlight 11

12 The Problem with Inventing Names Border paintinside() paintinside() Image paintinside() Highlight paintinside() 12

13 The Problem with Inventing Names Border paintinside() paintinside() Image paintinside() Highlight paintinside() Other workarounds: Decorators/Delegation, Aspects 13

14 Border and in Beta Border Image Highlight class Border... void { // draw a border:...; inner.; class... void { // draw a label:...; 14

15 and Border in Beta Border Image Highlight class... void { // paint the background:...; inner.; class Border... void { // draw a border:...; inner.; 15

16 Fixed and Border in Beta paintbackground() Border class... void paintbackground() { // paint the background:...; void { inner. else paintbackground(); Image Highlight class Border... void { paintbackground(); // draw a border:...; inner.; 16

17 in Beta paintbackground() Border paintlabel() class... void paintlabel() { // draw a button label:...; void { inner. else paintlabel(); Image Highlight 17

18 Image and Highlight in Beta paintbackground() Border Image paintlabel() Highlight class Image... void { // draw image // (don't call paintlabel):...; class Highlight... void { // replace background with // blue gradient:...; paintlabel(); // draws label 18

19 Combining Beta and Java Styles Border Image Highlight 19

20 Combining Beta and Java Styles Border Image Highlight 20

21 Combining Beta and Java Styles Border Image Highlight 21

22 Combining Beta and Java Styles Border Image Highlight 22

23 Combining Beta and Java Styles Border Image Highlight 23

24 Code for Beta/Java Combination Border class... java void { // paint the background:...; Image Highlight 24

25 Code for Beta/Java Combination Border class Border... beta void { // paint background: super.; // draw a border:...; inner.; Image Highlight 25

26 Code for Beta/Java Combination Border class... java void { // draw a button label:...; Image Highlight 26

27 Code for Beta/Java Combination Border class Image... beta void { // draw image, // don't call super // for label:...; inner.; Image Highlight class Highlight... java void { // replace background with // blue gradient:...; // draw label super.; 27

28 Summary: Java to Beta/Java Combination Add java and beta keywords for methods Add inner statement: inner.identifier (Expression,... Expression) else Statement 28

29 Operational Semantics: Calling paint on Border Border 29

30 Calling paint on Border: Method Dispatch new Border().; Border 30

31 Calling paint on Border: Method Dispatch Highest method declared beta or lowest method, if none new Border().; Border 31

32 Calling paint on Border: Method Dispatch Highest method declared beta or lowest method, if none new Border().; Border 32

33 Calling paint on Border: Method Dispatch Border class Border... beta void { super.;... inner. else...; 33

34 Calling paint on Border: super Dispatch Border class Border... beta void { super.;... inner. else...; 34

35 Calling paint on Border: super Dispatch Next method above in hierarchy Border class Border... beta void { super.;... inner. else...; 35

36 Calling paint on Border: super Dispatch Next method above in hierarchy Border class Border... beta void { super.;... inner. else...; 36

37 Calling paint on Border: super Dispatch Next method above in hierarchy Border class... java void { // paint the background:...; 37

38 Calling paint on Border: inner Dispatch Border class Border... beta void { super.;... inner. else...; 38

39 Calling paint on Border: inner Dispatch Next method below declared beta or lowest method, if none Border class Border... beta void { super.;... inner. else...; 39

40 Calling paint on Border: inner Dispatch Next method below declared beta or lowest method, if none Border class Border... beta void { super.;... inner. else...; 40

41 Operational Semantics: Calling paint on Border 41

42 Calling paint on : Method Dispatch new ().; Border 42

43 Calling paint on : Method Dispatch Highest method declared beta or lowest method, if none new ().; Border 43

44 Calling paint on : Method Dispatch Highest method declared beta or lowest method, if none new ().; Border 44

45 Calling paint on : Method Dispatch Border class Border... beta void { super.;... inner. else...; 45

46 Calling paint on : inner Dispatch Border class Border... beta void { super.;... inner. else...; 46

47 Calling paint on : inner Dispatch Next method below declared beta or lowest method, if none Border class Border... beta void { super.;... inner. else...; 47

48 Calling paint on : inner Dispatch Next method below declared beta or lowest method, if none Border class Border... beta void { super.;... inner. else...; 48

49 Calling paint on : inner Dispatch Next method below declared beta or lowest method, if none Border class... java void { // draw a button label:...; 49

50 Operational Semantics: Calling paint on Image Border Image 50

51 Calling paint on Image: Method Dispatch new Image().; Border Image 51

52 Calling paint on Image: Method Dispatch Highest method declared beta or lowest method, if none new Image().; Border Image 52

53 Calling paint on Image: Method Dispatch Highest method declared beta or lowest method, if none new Image().; Border Image 53

54 Calling paint on Image: Method Dispatch Border class Border... beta void { super.;... inner. else...; Image 54

55 Calling paint on Image: inner Dispatch Border class Border... beta void { super.;... inner. else...; Image 55

56 Calling paint on Image: inner Dispatch Next method below declared beta or lowest method, if none Border class Border... beta void { super.;... inner. else...; Image 56

57 Calling paint on Image: inner Dispatch Next method below declared beta or lowest method, if none Border class Border... beta void { super.;... inner. else...; Image 57

58 Calling paint on Image: inner Dispatch Next method below declared beta or lowest method, if none Border class Image... beta void { // draw image, // don't call super // for label:...; inner.; Image 58

59 Compiling Method Dispatch Border Image 59

60 Compiling Method Dispatch Border Image paint paint Border paint Border paint Border 60

61 Compiling super Calls Border class Border... beta void { super.;... inner. else...; Image 61

62 Compiling super Calls Border class Border... beta void { in class... inner. else...; Image 62

63 Compiling inner Calls Border Image 63

64 Compiling inner Calls 0 Border Image 64

65 Compiling inner Calls 0 Border class Border... beta void { super.;... inner. else...; Image 65

66 Compiling inner Calls 0 Border class Border... beta void { super.;... at index 1 Image 66

67 Compiling inner Calls 0 Border class Border... beta void { super.;... at index 1 1 Image 67

68 Compiling inner Calls paint 0 0 Border paint 0 Border 1 null paint 0 Border 1 1 Image paint 0 Border 1 Image 2 null 68

69 Performance Performance unchanged with these modifications All java methods behave exactly like normal Java Additional 250 lines of code to 2800-line object system 69

70 Model and Implementation Model based on CLASSICJAVA [Flatt, Krishnamurthi, Felleisen 98] Soundness proof in paper Implemented in v299 of PLT Scheme 70

71 Use in Practice: on-close and render-value Methods on-close method of editor called when window closed Includes important code to be executed Must be in control render-value method of language converts values to strings Sometimes language wants control certain values always displayed the same Sometimes gives up control to subclasses 71

72 Related Work CLOS [Keene, 1988], gbeta [Ernst, Ph.D. Thesis, 1999] Cook [Ph.D. Thesis, 1989], Clark [GEC Journal of Research, 1994] Bracha and Cook [OOPSLA 1990], Ancona and Zucca [PLILP 1997, MSCS 1998], Duggan [ECOOP 2000], Bettini, et al. [WOOD 2003], GNU EDMA [Oliveira] 72

73 Conclusions Programmers need super and inner in same language Method can maintain control or give control as desired Developed simple system of determining control Easy to implement Border Image Highlight Implementations: