YOU WILL ANYHOW CHAPTER 11 Plan To Throw One Away.

YOU WILL ANYHOW

CHAPTER 11

Plan To Throw One Away

Pilot Plant

Three phases of plant production Design Plant Pilot Plant Production Plant

Throwaway System

Failed concept in system programmingOn schedule delivery often means the first

thing builtBarely useableOften follow-up systems are neededQuestion: Build a throwaway system in

advance or deliver it to the customer?

Results of Implementing a Throwaway

Buys builders timeAgony for customersDistraction for builders by customersBad reputation for product and builders

Throwing away the Throwaway

Giving the throwaway to the customer

The Only Constancy is Change

Delivers satisfaction of a users needs rather than any tangible product. And that the users perception of that need will change as programs are built and used.

Product change is inevitable. The programmer must be prepared for it rather than assuming it won’t happen.

Plan the System for Change

ModularizationExtensive subroutinesPrecise and complete definition of interfacesAll with complete documentationSelf-documenting in high-level languages

reduces errorsCompile-time operations to include standard

declerations

Plan the Organization for Change

Broader job assignments to make workers more flexible

Large projects need multiple lead programmers under the manager

The boss must keep his managers flexible as their talents allow

Workers should be able to temporarily handle the workload for anyone in the project both up and down the ladder

Two Steps Forward One Step Back

Maintenance costs are usually 40% more than development costs

The more users the more bugs are foundFixing a defect has a high chance to cause anotherRegression Testing takes previous battery of tests

and tests them against the new version of the system

Hence the importance of addressing problems early

One Step Forward One Step Back

With large systems: as the number of fixes increase there will eventually be a point were these fixes will not gain any ground and new problems will arise from them

The system while technically still useable has worn out and an entirely new system needs to take over

Conclusion

BETA