Decompose Conditional.
You have a complex conditional (if-then/else or switch).
Decompose the complicated parts of the conditional into separate methods: the condition, then and else.
##Example
if (date.before(SUMMER_START) || date.after(SUMMER_END)) {
charge = quantity * winterRate + winterServiceCharge;
}
else {
charge = quantity * summerRate;
}if (isSummer(date)) {
charge = summerCharge(quantity);
}
else {
charge = winterCharge(quantity);
}##Why Refactor
The longer a piece of code is, the harder it’s to understand. Things become even more hard to understand when the code is filled with conditions:
-
While you’re busy figuring out what the code in the
thenblock does, you forget what the relevant condition was. -
While you’re busy parsing
else, you forget what the code inthendoes.
##Benefits
-
By extracting conditional code to clearly named methods, you make life easier for the person who’ll be maintaining the code later (such as you, two months from now!).
-
This refactoring technique is also applicable for short expressions in conditions. The string
isSalaryDay()is much prettier and more descriptive than code for comparing dates.
##How to Refactor
-
Extract the conditional to a separate method via Extract Method.
-
Repeat the process for the
thenandelseblocks.
