Lecture #3 Agenda Cell phones off & name signs out Questions? Activity Problem solving

I have a question for you! The question was: What did you have for breakfast today?

Activity The goal of this short activity is to demonstrate two things: 1.objects have behaviors 2.sending message to objects can trigger those behaviors

Activity details 3 volunteers, a.k.a. objects When I tell you to…you should… STARTbegin doing jumping jacks STOPstop jumping, and stand normally anything elsedo nothing When I tell you to…you should… STARTstart counting slowly, 0…1…2… etc, but always starting at zero STOPstop counting, but remember where you left off CONTINUEkeep counting up from where you left off anything elsedo nothing When I tell you to…you should… anything at alldo nothing

Activity Review Why did we do this activity? What is an object?

Problem solving How do we go about solving a problem? Simplification through abstraction is key. –Essay writing process –A process of iterative refinement Apply same idea to writing software

Executable Model Conceptual Model Apply same idea to developing software solutions:

The conceptual model A model of the problem domain Problem domain consists of: –objects properties capabilities –relationships between objects

PROGRAM CODE Executable Model MACHINE EXECUTABLE Initial Conceptual Model Problem Domain Iterative refinement of model Compilation A more refined picture (iterative refinement in action!)