Outline
• Designing a computational community
for WordGames
– What are Word Games?
– Communities:
• Transformers and Connections
• User and the System
– Building a Transformer
• High level design
• Low level design
– Rules and Methods
– Classes and Instances
– Fields and Constructors
Fundamentals of Software
Development 1
}
Next session
Slide 1
Word Games: Transformers
• Our system will have many transformers like
– Pig Latin
These transformers
will be
interconnectable
modules like Legos!
• Hello  ello-Hay
• How have you been?  ow-Hay ave-hay ou-yay een-bay?
– Ubby Dubby
• Hello => Hubbellubbo
• How have you been? => Hubbow hubbave yubbou bubbeen?
– Capitalizers: “HELLO”
– Name Droppers: (“Maria says Hello”, “Rumi says Hello”)
– And more, e.g:
•
•
•
•
Combiner: Listen and combine two inputs into one
Repeaters: Produce two outputs from one
Delayers: Don’t produce anything until they are signaled
Network-senders: Move words from one computer to another
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Download
and run the
WordGames
demo
Slide 2
Designing a Community
• What are the key questions for designing a
computational community?
–
–
–
–
Determine the desired system behavior
Identify the entities
Specify entity interaction
Specify entity operation
• How to start?
– Top-down: high-level and add details
– Bottom-up: low-level details combine to form system
– Today: in the middle, with a community of interacting
transformers and connections
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Slide 3
A Community of
Transformers and Connections
• Each Transformer is an entity
– Transformer interactions, version 1
• Read a word/phrase (from a connection)
• Write a word/phrase (to a connection)
• Each Connection is an entity
– Like tin-can telephones
• So Transformers don’t need to know about each other
– Connection interactions
• Accept a word/phrase written to it
• Supply that word/phrase when requested (read)
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Slide 4
Other Entities in the Community
• The User
– User interactions
• Create a Transformer (of a specified type)
• Connect two Transformers (in a particular order)
• How can we accomplish creating and connecting
transformers?
• Answer: Through a user interface
• Along with modifications to the Transformer interactions
– User interface interactions
• Create a Transformer (of a specified type)
• Create a Connection between two Transformers
Fundamentals of Software
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Slide 5
Transformer interactions, version 2
• How do Transformers interact with other
entities?
– Each Transformer has Connections
• Accept input Connection(s)
• Accept output Connection(s)
– Communication
• Read word(s) (from a Connection)
• Write word(s) (to a Connection)
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Slide 6
Recap
• We have answered:
– System Behavior
• Allows a user to play various word games
– Members of the community
• One instance of User and User interface
• Many instances of Transformers & Connections
– Entity Interaction
• Read/write through connections
• What is the remaining question?
– Answer: Entity operation
• How does each entity work? What goes inside each one?
– For example: How do Transformers work? Is a Transformer a
community (if so, of what?) or an instruction-follower? (See next slide.)
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Slide 7
Building a Transformer
• Transformer implementation must be able to:
– Accept input Connection(s)
– Accept output Connection(s)
– Have its own instruction-follower that acts independently to:
Read input, transform, write output
• Different types of transformers may do the transformation differently
• Each Transformer is itself a community!
– ConnectionAcceptors (input/output)
• E.g., acceptInputConnection: “store the input away someplace so that you
can use it later”
– Entities that perform startup tasks when the Transformer is constructed
– Independent instruction-follower
• We’ll focus on this
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Slide 8
goodbye
Transformer Example:
Capitalizer
Hello
Capitalizer 1
Capitalizer 2
GOODBYE
• Capitalizer:
1. Read the input
2. Produce a capitalized version of it
3. Write this as output
HELLO
• Each Capitalizer does the same thing but with a
different output based on its input
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Slide 9
Transformer Example:
NameDropper
Maria
Hello
Rumi
Rumi says Hello
•
NameDropper:
1.
2.
3.
•
Maria says Hello
Read the input
Produce a phrase containing its own name, the word “says,” and the input
Write this as output
Each NameDropper has its own name to drop
–
–
All Capitalizers have the same instructions and same data
All NameDroppers have the same instructions and the same structure,
but each has its own data associated with it (i.e., the name that it
drops)
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Slide 10
Other Transformer Examples
•
Repeater:
1.
2.
3.
•
Read the input
Write this to one OutputConnection
Write this to the other OutputConnection
PigLatin:
1.
2.
3.
Read the input
Produce a new phrase containing all but the first letter,
then the first letter, then “ay”
Write this as output
Fundamentals of Software
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Slide 11
Recap
•
We have answered (at least partially):
– System behavior?
•
Allows a user to play various word games
– Members of the community?
•
(one) User interface and User , (many) Transformers, (many) Connections
– How do they interact?
•
•
User operates user interface, which creates Transformers and Connections
Transformers communicate through Connections
– What goes inside a transformers: ConnectionAcceptors, ... plus an
instruction-follower with rules, such as for Capitalizer:
1. Read input
2. Produce capitalized version of it
3. Write output
•
Next session: how to implement such rules!
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Slide 12