Cardinal Sins of Programming

What I am going to put here is nothing new or enlightening for a seasoned software developer, it’s just my trials and tribulations working through some heavily screwed projects over the course of my career.

So what are those software (mal)practices which sound death knell and ensue disaster? Well, here are my top recipes for embracing pain

1. Code Repetition – Remember DRY aka Do not Repeat Yourself. Even if you repeat a mere 3/4 lines of code in 10 odd places just pause and think over. Something ought to be fishy, try to put that repetition into a function, reuse the code. I have burnt my fingers fixing repeated lines of code in 10 to 100 odd places, even a full package of Java files being completely duplicated to another package. Just remain ruthless if you see duplication, it should never be there, don’t hesitate to select and hit del, even if your manager is going to fire you for that.

2. Intermixing logic – Or simply violating SRP (Single Responsibility Principle). Its really catastrophic to mix UI logic with business logic. It just makes the whole code very difficult to read/debug and even more difficult to change anything. Suppose you want a new UI for the same logic, you are screwed, you have to recode the entire business logic again or refactor the current code to separate out business logic from UI. In this aspect I need to point out a horrible technological offering from Java Stable – JSP. If not used carefully JSP spell death knell. It’s so easy to mix db calls/business logic and UI HTML into the JSP. But what we get out of this shortcut is a code mass which totally undecipherable, not at all debuggable and what more stack traces point to the dynamic servlet code line numbers of the JSP. I loathe JSPs and wish Sun never gave so much power to the naive user to intermix things and screw up life.

3. Conventions – How do you feel when you see code with variables test1, test2, test5, i, j, looper, arraylist, map1, list1 etc. Terrible and horrible. You read method half way then you wonder what this test1 actually is then you scroll up then find out what is getting assigned to it, then come down and re-read. The naming convention is not confined to Java variables or methods, even for HTML tags. Its really a bad idea to give tag ids as myForm or myButton. I faced really a real night mare when we decided to consolidate all JavaScrips littered over JSPs to a single JS and include it every where. In the end you have 10 functions with name submitForm. You are screwed, you have a real pain to correct them If your form is an Order entry form right name for form id would be orderForm and submit of that form would invoke submitOrder() method in JavaScript.

4. Looong methods – How long can a method be? 1000 lines, 4000 lines? Well I had opportunity to debug upto 10k lines of code in a method. My pea brain just could not hold on that and I just had to leave that and pray before I run those methods. I personally feel 50 is the max number of lines you can have, 50 is upper limit of tolerance, ideally a method need to be 10-15 lines of code in a well crafted software.

5. Exposing the internals – If you have class, don’t expose the internals of it to outside. If you maintain list of names as HashMap inside a class, don’t tell world that you are using HashMap. Just keep it with you and give neat interfaces to outside like
void addStudent(int id,String name)
Iterable getStudentNames()
void getStudentName(int id)

rather than using
HashMap getStudentMap()

In the latter case call can even modify the Map without you being aware of it and at later point if you are going to change the Map to a Student Class, you are screwed up because all those who are exposed to your internals need to be updated.

6. Building the code on ArrayList, HashMap – ArrayList and HashMaps are good, but should be the lowest level of implementation never exposed out through public APIs or methods. I had tremendous experiences where a HashMap contains 10 keys, 1st key returns another HashMap which intern has 10 keys and each of those keys have ArrayList, Array, String, Integer etc. Then there were wonderful data structures like an Array of ArrayList. These kind of things drive you nuts and crazy, unless you debug line by line and print line by line its never clear what goes where. Class is the most powerful abstraction you have and try to encapsulate things within the objects and pass around objects rather than Lists and Maps.

7. Think a little bit ahead – Yea its not good to code for requirements which you are not having today, but still for some cases it’s good to assume certain things and give that flexibility in the code. A case in point is internationalization, just don’t litter messages and boiler plate texts in Java/JSP/JavaScripts, have mechanism in place from beginning itself, even though you may just show things in English alone. Another aspect is db, it’s not good to assume one db and code it, code ought to be db agnostic. I had seen code where things were assumed to be always on Oracle and they take liberty of using sequences or sysdate (both Oracle specific) and one fine morning customer comes and tell you, well I want only SQL/Server. You are doomed.

8. Passion – (or lack of it) Majority of those who write code, do it for getting pay cheque at month end. Building code is cheap and easy. Anyone with a reasonable aptitude can do it. But crafting it to be readable, extensible, maintainable requires lot of pain, learning and rework. If you are not willing to take that pain, not willing to learn how to write testable software, then don’t just do it.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s