Post on 19-Dec-2015
University of British Columbia
Software Practices Lab
Expressive Programs
Through Presentation
ExtensionAndrew D. Eisenberg
andGregor Kiczales
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 2
Code that Looks Like the Design
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 3
Code that Looks Like the Design
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 4
• Familiar goals, many approaches– Languages
• abstraction level, domain specificity, extensibility…– Editors
• language aware, highlighting, formatting…
• Contributions – New editor/compiler architecture
• synergistic presentation and semantic extensibility• compatible with existing code, tools, practice
– Eclipse-based implementation– Examples
• how light-touch uses of idea can be powerful
Code that Looks Like the Design
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 5
Desirable Properties• Extensibility
– presentation • more than colors, fonts—substantial
difference from concrete syntax• free-form editing
– semantic• like syntax macros
– (abstract syntax graph, not tree)
• Compatibility– with existing code, tools– incremental adoption
• Traceability– of errors– for other tools
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 6
Tool chains
Raw Text (Byte) Code
Other Tools
Display/Edit
Compiler/
Interpreter
Editor
Gnu/Linux
•Language extensibility•code formatting (colors, bold, italics, etc)•text pre-processors
•Communication is line number and character-based
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 7
semantic extensibility
Syntax Macros
AST Expanded AST
Other Tools
Display/Edit
Lisp/Scheme
Raw Text (Byte) Code
•Language extensibility•code formatting•macros
•Communication is line number and character-based
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 8
(Byte) CodeExpanded AST
Structure (Syntax-Directed) Editors
AST
InterlispCornell Program Synthesizer
Other Tools
Display/Edit
Raw Text
•Language extensibility•code formatting•pretty-printing (line breaks, white space, etc)•macros
•Communication between display and byte code can be AST-based
semantic extensibility
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 9
State of the Practice IDEs
•AST easy to create from raw text•cheap, reliable, and fast•incremental•simultaneous maintenance of raw text & AST
•Communication is line-number or AST-based•Restricted extensibility
Eclipse, IntelliJ, Visual Studio, …
Other Tools
AST
Display/Edit
Raw Text (Byte) Code
semantic extensibility
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 10
Raw Text
Display-Driven AST
•AST*—Abstract Syntax Graph•more freedom in displaying code
•Program store is determined by editor•communication is AST-based only•cannot use text-based tools
•Language extensibility•presentation•macros (DrScheme) and AST expansion (Intentional Programming)
DrSchemeIntentional ProgrammingSubtext
Other Tools
Display(AST*)
(Byte) Code
Store
AST
Expanded AST
semantic extensibility
presentation extensibility
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 11
(Byte) CodeExpanded AST
Other Tools
Display/Edit
Raw Text
Presentation Extension of Plain Text
•Language extensibility•presentation•syntactic
•Compatible with modern IDEs•Tool infrastructure•Raw text is accessible
(with syntactic extension)
AST*
semantic extensibility
presentation extensibility
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 12
ExpandedAST
Architecture
Legacy Tools
Display
AST
Byte CodeRaw Text
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 13
ExpandedAST
Architecture
Display
AST
Byte Code
Legacy Tools
Raw Text
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 14
ExpandedAST
Architecture
Display
AST
Byte CodeRaw Text
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 15
Raw Text
ExpandedAST
Architecture
Display
Byte Code
AST
Pair of disjoint, but communicating metaobject protocols
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 16
Implementation
Display
Byte Code
AST
Expanded AST
AST+EditMOs
AST+CompileMOs
Boxes
Controllers
M V
C
Error
Propagation
CTMOP
ETMOP
Pair of disjoint, but communicating metaobject protocols
Raw Text
Edit-Time Metaobject Protocol
Compile-Time Metaobject Protocol
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 17
Traceability
Display
Byte Code
AST
Expanded AST
AST+EMOs
AST+CMOs
Boxes
Controllers
CTMOP
ETMOP
Pair of disjoint, but communicating metaobject protocols
Pair of disjoint, but communicating metaobject protocols
Raw Text
Edit-Time Metaobject Protocol
Compile-Time Metaobject Protocol
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 18
Traceability Allows Error Propagation
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 19
Traceability Allows Code Completion
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 20
• Can be used to create graph edges
• Annotations are familiar
• Annotations work with existing tools
• Valid Java syntax
• Attached to source code
@Getter("get")
@Setter("set")
private int x;
@Previous
private int y;
Metaobjects Serialize to Annotations
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 21
AspectJ Code Style↔Annotation Style
@org.aspectj.lang.annotation.Aspect()
class PointObserving{
@org.aspectj.lang.annotation.After(value="changes(p)")
void advice$aj$0(Point p){
Screen.notify();
}
@org.aspectj.lang.annotation.Pointcut(
"this(p) && execution(void Point.set*(int))")
void changes(Point p){}
}
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 22
Uses
@ca.ubc.cs.etmop.annotations.Uses(
type=BufferedReader.class,
name="file",
init="new BufferedReader(new FileReader(fName))")
public String getFileContents(String fName) {
...
}
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 23
Only presentation extensibility, no semantic
Backquote—Code Generation
return makeMethod( makeModifiers(PUBLIC), makeVoid(), makeName(makeSetterName(varName)), makeParameters( makeParameter(makeType(typeName), makeName(varName))), makeBlock(makeExpressionStatement( makeAssignment(makeFieldAccess( makeThis(), makeName(varName)), makeName(varName)))));
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 24
Equations
public static double mean( final List<Integer> x) {@Equation(Return.DOUBLE)
int MOP_ANNOTATION_HOLDER$0;return Equ.div(
new Summer() { public int body(int i) { return x.get(i); } }.sum(0, x.size() - 1), x.size()); }
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 25
Equation Video
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 26
Stream Processing Automaton
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 27
Presentation Extensions
(Byte) CodeExpanded AST
AST
Other Tools
Display/Edit
Raw Text
RawText
Display
Byte Code
AST
Expanded AST
AST+EMOs
AST+CMOs
Boxes
Controllers
CTMOP
ETMOP
ErrorPropagation
Andrew Eisenberg and Gregor Kiczales — University of British Columbia 28
Questions?
(Byte) CodeExpanded AST
AST
Other Tools
Display/Edit
Raw Text
RawText
Display
Byte Code
AST
Expanded AST
AST+EMOs
AST+CMOs
Boxes
Controllers
CTMOP
ETMOP
ErrorPropagation