Methods of simplifying ugly nested if-else trees in C#

Question

Sometimes I\'m writing ugly if-else statements in C# 3.5; I\'m aware of some different approaches to simplifying that with table-driven development, class hierarchy, anonimous m

Answer 1

Good question. "Conditional Complexity" is a code smell. Polymorphism is your friend.

Conditional logic is innocent in its infancy, when it’s simple to understand and contained within a few lines of code. Unfortunately, it rarely ages well. You implement several new features and suddenly your conditional logic becomes complicated and expansive. [Joshua Kerevsky: Refactoring to Patterns]

One of the simplest things you can do to avoid nested if blocks is to learn to use Guard Clauses.

double getPayAmount() {
if (_isDead) return deadAmount();
if (_isSeparated) return separatedAmount();
if (_isRetired) return retiredAmount();
return normalPayAmount();
};  

The other thing I have found simplifies things pretty well, and which makes your code self-documenting, is Consolidating conditionals.

double disabilityAmount() {
    if (isNotEligableForDisability()) return 0;
    // compute the disability amount

Other valuable refactoring techniques associated with conditional expressions include Decompose Conditional, Replace Conditional with Visitor, Specification Pattern, and Reverse Conditional.