Objects History, Pluquet Frédéric. ESUG 2006, Prague

1. bjects History
Pluquet Frédéric
Université Libre de Bruxelles (Brussels)
fpluquet@ulb.ac.be
For ESUG’06 - At Prague
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2. Pluquet Frédéric
fpluquet@ulb.ac.be
What is Objects History ?
Object-Oriented Model
to save history (each state)
of live objects
efficiently
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3. Pluquet Frédéric
fpluquet@ulb.ac.be
Example :Without Objects History
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x: 0
y: 0
x ← 10
::Point
x: 10
y: 0
::Point
Old values of attributes
are lost !
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4. Pluquet Frédéric
fpluquet@ulb.ac.be
Example : With Objects History
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x: 0
y: 0
x ← 10
::Point
x: 0,10
y: 0
::Point
x: 0,10,20
y: 0
::Point
x ← 20
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5. Pluquet Frédéric
fpluquet@ulb.ac.be
Possible questions to the system
What are all states of this object ? What
are all values of x ?
What are the values of x when y equals 10 ?
What is the state of this object at time t ?
(t can be any time)
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6. Pluquet Frédéric
fpluquet@ulb.ac.be
Applications (1/3)
Classical applications
CVS, SVN, ...
Add history to existing applications
Undo/Redo in Text Editor
SmallWiki
...
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7. Pluquet Frédéric
fpluquet@ulb.ac.be
Applications (2/3)
Adding states to execution traces
To be able to inspect state of objects
at any given point in past
“Timeless breakpoints”
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8. Pluquet Frédéric
fpluquet@ulb.ac.be
Applications (3/3)
Use Objects History to allow backtrack
with side-effects in Soul
class(?c),
[?c compile: ?code],
classNameMatching(?c, ‘A*’)
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9. Pluquet Frédéric
fpluquet@ulb.ac.be
State of research
Prototype for VisualWorks 7.4 and
Squeak 3.9
Prototype of a trace recorder using
Objects History (VW 7.4)
Made text editors of VW 7.4 persistent
using Objects History to undo / redo
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10. Pluquet Frédéric
fpluquet@ulb.ac.be
Future Work
Optimization of Objects History
Incorporate Objects History into existing
applications
Collaboration with Marcus Denker
ByteSurgeon + Objects History =
an efficient Trace Recorder ?
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11. Pluquet Frédéric
fpluquet@ulb.ac.be
Questions ?
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origin:
corner:
::Rect
x: 0,60
y: 0,15
::Point
x: 0,10,30
y: 0,5,10
::Point
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