The Dynamic Language is not Enough

Most today’s software is highly static, even if it is written in a dynamic language like Smalltalk. Developers are not encouraged to extend the frameworks they are using; and end-users are unable to change the features of their software without initiating a new development effort. In contrast, extensible software is designed for change; and customizable software can be adapted to new needs without requiring an in-depth knowledge of the underlying implementation domain.

In this presentation I will investigate on how to write truly dynamic software and I will distill common patterns of software customizability. As running examples I present tools that I worked on during my path of discovering Smalltalk. One of these examples is Magritte, a dynamic meta-model that gives end-users the possibility to customize their applications without the need of an additional development effort. Another example is Helvetia, an infrastructure enabling on-the-fly customization of the programming language and development environment.

Transcript

1. The Dynamic Language is not Enough Lukas Renggli
5. Static Software
6. Static Software Constant
7. Static Software Constant Fixed
8. Static Software Constant Fixed Final
9. Dynamic Software
10. Dynamic Software Adaptive
11. Dynamic Software Adaptive Extensible
12. Dynamic Software Adaptive Customizable Extensible
13. Static Language Dynamic Language Static Software Dynamic Software
14. :-( Static Language Dynamic Language Static Software Dynamic Software
15. :-( :-| Static Language Dynamic Language Static Software Dynamic Software
16. :-| Static Language Dynamic Software
17. :-| Static Language Dynamic Software
18. :-( :-| Static Language Dynamic Language Static Software Dynamic Software
19. :-( :-| :-S Static Language Dynamic Language Static Software Dynamic Software
20. :-S Dynamic Language Static Software no support easier can always get away with reflection faster don’t know how to do it too complex out-of- the-box
21. :-( :-| :-S :-) Static Language Dynamic Language Static Software Dynamic Software
22. :-) Dynamic Language Dynamic Software
23. 1 Subclassing 2 Extending 3 Meta-Modeling 4 Meta Meta-Modeling 5 Composing 6 Transforming
24. Subclassing 2 Extending 3 Meta-Modeling 4 Meta Meta-Modeling 5 Composing 6 Transforming
25. Subclassing Extending 3 Meta-Modeling 4 Meta Meta-Modeling 5 Composing 6 Transforming
26. Subclassing Extending Meta-Modeling 4 Meta Meta-Modeling 5 Composing 6 Transforming
27. Subclassing Extending Meta-Modeling Meta Meta-Modeling 5 Composing 6 Transforming
28. Subclassing Extending Meta-Modeling Meta Meta-Modeling Composing 6 Transforming
29. Subclassing Extending Meta-Modeling Meta Meta-Modeling Composing Transforming He vetia
30. Subclassing
31. The framework for developing sophisticated web applications in Smalltalk
32. Add new functionality by adding a new subclass.
33. WAComponent renderContentOn:
34. WAComponent renderContentOn: MyComponent renderContentOn:
35. Template Method
36. Extensible Customizable Adaptable
38. WAToolPlugin label execute
39. WANewSession... WATiming... WAToolPlugin label execute ...
40. WAToolPlugin label execute allPlugins self  allSubclasses collect:  [  :each  |  each  new  ]
42. WAHaloPlugin label execute allPlugins self  allSubclasses collect:  [  :each  |  each  new  ]
43. Discussion ‣ Template Method Pattern ‣ Simple ‣ Lightweight ‣ Portable ‣ No extra infrastructure
44. Other Users ‣ Monticello Repository Types ‣ OmniBrowser Commands ‣ Code Critics Rules ‣ TextLint Rules (later today) ‣ Pier Commands, Views, Structures ‣ Magritte Description Types
45. Extending
46. Add new functionality by adding a new method.
48. menuCommandOn:  aBuilder   <worldMenu>   (aBuilder  item:  'Shout  Workspace')     parent:  #Tools;     action:  [  self  open  ]
49. menuCommandOn:  aBuilder   <worldMenu>   (aBuilder  item:  'Shout  Workspace')     parent:  #Tools;     action:  [  self  open  ] PragmaCollector  allSystemPragmas      select:  [  :each  |  each  keyword  =  #worldMenu  ] }
50. Discussion ‣ Simple ‣ Lightweight ‣ Long utility methods ‣ Encourages class-extensions
51. Alternatives to Pragmas ‣ Naming convention for selector names ‣ Naming convention for protocol names ‣ All methods of a specific class
52. Other Users ‣ Pier Value Links ‣ Pharo Compiler Primitives, System Settings ‣ OmniBrowser Commands, Obsolete Commands, and Browser Meta-Model
53. Meta-Modeling
54. Create a first-class description of the domain.
59. Environment
60. Environment Category
61. Environment Category
62. Environment Class Comment Metaclass Category
63. Environment Class Comment Metaclass Protocol Category AllProtocol
64. Environment Class Comment Metaclass Protocol Method Category AllProtocol
66. OB-Web
67. OB-Mars
68. Discussion ‣ UI independent ‣ Domain-specific reflection ‣ Extensible using subclassing/extending ‣ Can cause meta-confusion ‣ Can be limiting or slow
69. Other Users ‣ GLORP Relational Object Mapping ‣ Glamour Browser Model ‣ Monticello Code Model ‣ Announcement Event Model ‣ Magritte Meta-Model
70. Meta Meta-Modeling
71. Create a first-class description of the description of the domain.
72. Address Object street = 'Schützenmattstrasse' plz = 3012 place = 'Bern' canton = 'Bern' :Address
73. Address Description street = 'Schützenmattstrasse' plz = 3012 place = 'Bern' canton = 'Bern' :Address label = 'Street' :StringDescription label = 'PLZ' required = true range = 1000..9999 :NumberDescription label = 'Place' required = true :StringDescription label = 'Canton' required = true sorted = true options = #( 'Bern' 'Zurich' ... ) :SingleOptionDescription label = 'Address' :Container description
74. result  :=  anAddress  asMorph   addButtons;   addWindow;   callInWorld Morphic Interpreter
75. result  :=  self  call:  (anAddress  asComponent   addValidatedForm;   yourself). Seaside Interpreter * * *
76. Other “Interpreters” ‣ Viewer building ‣ Editor building ‣ Report building ‣ Documentation ‣ Data validation ‣ Query processing ‣ Object filtering ‣ Object serialization ‣ Object copying ‣ Object indexing ‣ Object initialization ‣ Object extension ‣ Object adaption ‣ Object customization and much more ...
77. Domain Model Metamodel Meta- Metamodel <described-by> <described-by> Developer End User
78. Domain Model Metamodel Meta- Metamodel Magritte Developer <described-by> <described-by> Magritte End User
79. Object Description Type Object * * description attributes 1 * (b) Magritte onent Object * attributes 1 * nent erty Object Description Type Object * * description attributes 1 * (b) Magritte t Object Description Type Object * * description attributes 1 * (b) Magritte
80. Object Description Type Object * * description attributes 1 * (b) Magritte onent Object * attributes 1 * nent erty Object Description Type Object * * description attributes 1 * (b) Magritte t Object Description Type Object * * description attributes 1 * (b) Magritte
81. Object Description Type Object * * description attributes 1 * (b) Magritte onent Object * attributes 1 * nent erty Object Description Type Object * * description attributes 1 * (b) Magritte t Object Description Type Object * * description attributes 1 * (b) Magritte
82. Adaptive Object Model Run-time
83. End users customizability
84. Demo
85. Discussion ‣ Very powerful and flexible ‣ Runtime adaptive code ‣ End-user programmable code ‣ Can cause meta meta-confusion ‣ Can be slow
86. Other Users ‣ Gjallar Issue Tracker ‣ DabbleDB Online Database
87. Composing
88. Build something new by composing existing parts.
90. scanIdentifier self step. ((currentCharacter between: $A and: $Z) or: [ currentCharacter between: $a and: $z ]) ifTrue: [ [ self recordMatch: #IDENTIFIER. self step. (currentCharacter between: $0 and: $9) or: [ (currentCharacter between: $A and: $Z) or: [ currentCharacter between: $a and: $z ] ] ] whileTrue. ^ self reportLastMatch ]
91. #( #[1 0 9 0 25 0 13 0 34 0 17 0 40 0 21 0 41] #[1 0 9 0 25 0 13 0 34 0 93 0 76 0 157 0 112] #[1 2 38 0 21 2 38 0 25 2 38 0 26 0 13 0 34] #[0 1 154 0 16 0 21 0 25 0 26 0 34 0 40 0 41] #[0 1 210 0 76 0 81] #[0 1 214 0 76 0 81] #[1 0 173 0 76 0 177 0 81] #[0 1 134 0 16 0 21 0 25 0 26 0 34 0 40 0 41] #[1 1 46 0 21 1 46 0 25 1 46 0 26 1 69] #[1 1 54 0 21 1 54 0 25 1 54 0 26 1 54 0 34] #[0 2 102 0 21 0 25 0 26 0 34 0 40 0 41 0 76] #[0 2 50 0 21 0 25 0 26 0 76 0 79] #[1 1 13 0 76 2 85 0 124 1 21 0 125] #[1 2 89 0 17 2 30 0 21 2 30 0 82] #[1 2 93 0 21 2 97 0 82] )
92. Scannerless Parser Combinator
93. a..z a..z 0..9 ID  ::=  letter  {  letter  |  digit  }  ;
94. letter letter digit sequence choice many ID  ::=  letter  {  letter  |  digit  }  ;
95. letter letter digit sequence choice many id  :=  #letter  ,  (#letter  /  #digit)  star
96. letter letter digit sequence choice many id  :=  #letter  asParser  ,  (#letter   asParser  /  #digit  asParser)  star
97. Smalltalk + SQL Language + Regular Expression = Customized Smalltalk
98. Discussion ‣ The LEGO model ‣ New parts can be easily created ‣ Smalltalk provides elegant composition with binary operators
99. Other Users ‣ Brazil Widgets in Newspeak ‣ Seaside and Pier Widgets ‣ Refactoring Engine Change Objects
100. Transforming He vetia
101. Build something new by transforming existing parts.
102. Language Scope Language Concern Language Change Language Box
103. Language Scope Active?
104. Language Scope
105. ‣ System ‣ Packages ‣ Classes ‣ Methods Language Scope
106. Language Concern Semantics
107. Language Concern Transformation
108. Language Concern Context Menus Navigation Search Code Expansion Code Completion Error Correction Custom Inspector Refactorings Code Folding Highlighting Code Execution
109. Language Change Syntax
110. Language Change Smalltalk
111. Language Change Smalltalk + SQL Language
112. Language Change Smalltalk + SQL Language + Regular Expression
113. Smalltalk + SQL Language + Regular Expression = Custom Host Language Language Change
115. Demo
116. Discussion ‣ Very generic and powerful ‣ Usually requires extra infrastructure (for example Helvetia) ‣ Might be difficult to learn and apply
117. Other Users ‣ Refactoring Engine Rewrite Rules ‣ Compiler Hacks (ok, not really) ‣ XML, XSD Transformations ‣ SOUL, IntensiVE
118. Anything Else?
119. ‣ Subclassing ‣ Extending ‣ Meta-Modeling ‣ Meta Meta-Modeling ‣ Composing ‣ Transforming }How to make “tools” and “languages” extensible?
120. How to make the “object model” extensible?
121. Albedo Jorge Ressia
122. Object Class
123. Object Structural Meta-object Class
124. Object Structural Meta-object Class Behavioral Meta-object
125. :-( :-| :-S :-) Static Language Dynamic Language Static Software Dynamic Software
126. :-) lukas-renggli.ch @renggli Dynamic Software