Defusing the IF-Strategy
Have you ever wondered how IFs impact on your code?
Lot of developers apply the "IF Strategy" to deal with growth, change and complexity:
IF ( new condition) { new code }
Unfortunately, by doing that regularly, they increase the complexity of their software system. As a consequence, the next changes will cost more and more!
The goal of the Anti-IF Programming is to raise awareness of the risks of applying the "IF Strategy" and to draw attention to the importance of replacing it with other design techniques, more effective to deal with growth, change and complexity. Defusing the "IF Strategy" enables developers to get a code that is flexible, changeable and easily testable. This will help to avoid a lot of headaches and weekends spent debugging!
...about a software developer working in a company who was building up a nice platform. One day the boss calls the developer on the phone and says: "There’s a new task I need you to do for a really important client, and it must be done by the end of the day. All that’s needed," the boss continues "is to add a small piece of functionality to that class method you’ve been working on... it shouldn’t be too complex..."
The days go by...
and that small class, edit by edit, grows into a small code monster: the more you feed it with IFs, the bigger it grows!
Do you think it’s just a fairy tale?
Well, it’s not!
What follows below is a single class method taken from real code that is live on a server somewhere on the Internet right now. And this is just a "baby monster". The more you feed it, the bigger it grows!
calculateWageFor(Person aPerson) {
...
IF=> IF(aPerson.type == Person.EMPLOYEE) {
ordinaryHourlyWage = 15;
overtimeHourlyWage = 20;
IF=> IF(aPerson.status == Person.PARENTALLEAVE) {
ordinaryHourlyWage= ordinaryHourlyWage * .70; // 70%
IF=> IF(aPerson.daysOffLeft() > 10) {
ordinaryHourlyWage = ordinaryHourlyWage * 0.9; // 90%
}
}
salary = aPerson.ordinaryWorkHours *
ordinaryHourlyWage +
aPerson.overtimeWorkHours *
overtimeHourlyWage;
}
IF=> IF(person.type == Person.MANAGER) {
fixedWage = 3000;
monthlyBonus = lastYearsProfit * .10 / 12; // 10% monthly
IF=> IF(aPerson.status == Person.PARENTALLEAVE) {
monthlyBonus= monthlyBonus * .60; // 70%
IF=> IF(aPerson.daysOffLeft() > 10) {
fixedWage = fixedWage * 1; // 90%
monthlyBonus= monthlyBonus * 1; // 70%
}
}
salary = fixedWage + monthlyBonus;
}
IF=> IF(person.type == Person.CONSULTANT) {
dailyFee = 300;
workHours = aPerson.workHours();
realDays = workHours / 7;
salary = realDays * dailyFee;
}
return salary;
}
Pretty scary,huh?
Yes, it is.
And it happens everyday all over the web.
So, what can I do to help?