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Clean code
Naming
an introduction to Robert C. Martins
Classnames should be nouns: Customer
Methodnames should contain verbs: getName()
No abbrevations
Christian Engvall (@crilleengvall)
http://www.christianengvall.se/
int d; // elapsed time in days
Bad:
Good:
int elapsedTimeInDays;
Comments are lies
They get old and misleading over time
As small as possible!
Max 10 lines of code
Methods
Do only one thing
If/else
if(myBool) {
callToMethod();
}
else {
callToAnotherMethod();
}
The book
The site
Try/catch
arguments
Pass no more than three arguments
http://www.cleancoders.com/
http://www.amazon.com/Clean-Code-Handbook-Software-Craftsmanship/dp/0132350882/
public void delete(Customer customer) {
try{
deleteCustomer(customer);
}
catch(Exception error) {
logError(error);
}
}
No output arguments
private void logError(Exception error)
{
logger.log(error);
}
Don't pass booleans
Thoughts
DeleteEmployee(“Bob”, false, true);
Refresh your clean code habits now and then
You will probably thank yourself when needing to maintain the code you just wrote.
After a while it's easy to cut corners when clean coding, especially when maintaining legacy systems.
Example
code from http://softhouseeducation.com/produkt/clean-code-fem-minuter
return
The boy scout rule
Only one exit
Always leave the campground cleaner than you found it.
public void setupCall(PhoneNumber number) {
Exchange exchange = findExchange(number);
exchange.dial(number);
}
public class PhoneNumber {
private String number;
public PhoneNumber(String number) throws InvalidNumber {
validate(number);
this.number = number;
}
private validate(string number) {
hasCorrectLength(number);
containsOnlyDigits(number);
}
}
Don't return null
public void setupCall(String phoneNo) {
// Validate that number has correct length
if ( phoneNo.length() < 10 || phoneNo.length() > 18 ) {
throw new CallException(“Phone number must be between 10-18 digits long!”);
}
// Validate that number only has digits
if ( ! Pattern.matches(“^\\d*$”, phoneNo) ) {
throw new CallException(“Phone number is not a digit!”);
}
String countryCode = null; String areaCode;
if ( phoneNo.startsWith(“00”) ) { // International number
countryCode = phoneNo.substring(2, 2);
areaCode = phoneNo.substring(3,3);
} else {
areaCode = phoneNo.substring(0, 3);
}
Exchange exchange = findExchange(countryCode, areaCode);
exchange.dial(phoneNo);
}
No need to check for null:
unnecessary:
List <Employee> employees = getEmployees();
foreach(employee in employees) {
employee.raiseSalary();
}
List<Employee> employees = getEmployees();
if(employees != null) {
foreach(employee in employees){
employee.raiseSalary();
}
}