Transcript Program Development Cycle

The Program
Development Cycle
An Introduction to Programming Using Alice
Program Development Cycle
Modern software developers base many of
their techniques on traditional approaches to
mathematical problem solving.
One such approach is based on the how
engineers solve problems.
An Introduction to Programming Using Alice
Program Development Cycle
Engineers must:
•
Design a solution to a problem
•
Implement the solution
•
Test the solution
•
Fix any errors in the solution
An Introduction to Programming Using Alice
Program Development Cycle
This approach can be used in computer programming:
•
Design a solution to a problem (design a program)
•
implement the solution (code the program )
•
Test the solution (test the program)
•
Fix the solution (debug the program)
An Introduction to Programming Using Alice
Program Development Cycle
Once the software is working, improvements can
be designed into the system. This leads back to
design, creating a four-phase cycle.
Design
Debug
Code
Test
An Introduction to Programming Using Alice
Program Development Cycle
Design
Debug
Code
Test
An Introduction to Programming Using Alice
Program Development Cycle
Design
Many different techniques are used to design methods
in new software. Top-down development and modular
design are most common.
Tools include flowcharts, pseudo-code, storyboards,
and Universal Modeling Language (UML).
An Introduction to Programming Using Alice
Program Development Cycle
Design
In the design phase of object-oriented programming,
objects must be chosen from libraries, or the
properties and methods for new objects must be
described.
An Introduction to Programming Using Alice
Program Development Cycle
Design
Debug
Code
Test
An Introduction to Programming Using Alice
Program Development Cycle
The program development
cycle’s code phase includes
translating a software design
into a particular language,
and then entering that
language on the computer.
An Introduction to Programming Using Alice
Code
Program Development Cycle
Design
Debug
Code
Test
An Introduction to Programming Using Alice
Program Development Cycle
Testing can be rather complicated:
Does the new method do what it is supposed to do?
This is known as a test for correctness. Tests for
correctness measure whether the program meets the
original specifications.
Test
An Introduction to Programming Using Alice
Program Development Cycle
Testing can be rather complicated:
Is the method reasonably efficient? How much time
does it take for the method to complete its task, and
how much space does it use?
Test
An Introduction to Programming Using Alice
Program Development Cycle
Testing can be rather complicated:
Does the method have any undesirable side effects?
How does one program affects the performance of
another program, or one method affects another
method?
Test
An Introduction to Programming Using Alice
Program Development Cycle
Programmers perform unit tests and integration tests.
A unit test checks to see if a method works as
expected all by itself.
An integration test checks to see if a method
works in combination with other methods.
Test
An Introduction to Programming Using Alice
New Software
Method
Overall Program
Other methods
Testing Shell
New Software
Method
Unit
Test
Integration
Test
An Introduction to Programming Using Alice
New Software
Method
Other methods
Program Development Cycle
Programmers perform unit tests and integration tests.
A unit test checks to see if a method works as
expected all by itself.
An integration test checks to see if a method
works in combination with other methods.
Test
An Introduction to Programming Using Alice
Program Development Cycle
Design
Debug
Code
Test
An Introduction to Programming Using Alice
Program Development Cycle
Debug
The causes of any problems
discovered during testing need to
be isolated. Here unit tests are
most helpful.
Once you know the cause, you
can develop a plan for fixing the
problem, modify the necessary
methods, and then test again.
An Introduction to Programming Using Alice
Program Development Cycle
Design
Debug
Code
Test
An Introduction to Programming Using Alice
An Alice Development Cycle
Design
Describe the objects,
methods, and initial scene
for the new Alice world.
Debug
Implement
Correct each method’s
design and coding, and the
initial state of the world.
Add the necessary objects
to the world, position them,
and code their methods.
Test
Test each method to see
if it works by itself and
with other methods.
An Introduction to Programming Using Alice