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Lecture #4Ahmed Safwat
Muhamad HeshamAbdelrahman Al-Ogail
What about Singleton? Call for a new requirement. First try implementation. Meet today’s pattern. Second try implementation. Common uses. Project Description. What’s after all of this?
What have we didtill now?
You: Dad, I need pocket money.
Dad: *^^%^&@&**&^#&*%&*#%
Away
Available
Busy
busy
sign in
Offline
away
away
available
busy
available
All states are connected
to offline via sign out
Out of Pepsi
Pepsi Sold
No Money
Has Money
insert
money
eject
money
pepsi > 0
pepsi = 0
order pepsi
Running Idle
reach cliff
after a while
I want the enemy turn crazy when you collect a gem.
If you touch the enemy while it is crazy, you die and it turns idle again.
Double crazy enemy speed by 4 times once.
Running Idle
reach cliff
after a while
Crazy
gem
collectedgem
collected
player died
What do you think we need do this time ?
Violates Open Closed Princible.
Not object oriented. Further additions will
cause bugs. State transitions are
buried between if-else.
Exploring the pattern Let’s Google it!
Explaining the pattern Pattern class diagram
Pac-Man
Keyboard with Shift Key
Windows Live Mail (Offline/Online)
Pattern’s Challenge Try it yourself
Strategy/State conflict Challenge:
What are the differences between State and
Strategy Pattern?
What’s Next
State Pattern: Chapter 10 in Head First Strategy Pattern: Chapter 1 in Head First GoF: Behavioral Pattern Section Section: enhance way of drawing shapes
Further Reading
