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Tips to Comment the Code

based on 13 Tips to Comment Your Code

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1. Comment each level

Comment each code block, using a uniform approach for each level. For example:

• For each class, include a brief description, author and date of last modification

• For each method, include a description of its purpose, functions, parameters and results

Adopting comment standards is important when working with a team. Of course, it isacceptable and even advisable to use comment conventions and tools (such as XML inC# or Javadoc for Java) to facilitate this task.

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2. Use paragraph comments

Break code blocks into multiple “paragraphs” that each perform a single task, thenadd a comment at the beginning of each block to instruct the reader on what isabout to happen.

// Check that all data records

// are correct

foreach (Record record in records)

{

if (rec.checkStatus()==Status.OK)

{

. . .

}

}

// Now we begin to perform

// transactions

Context ctx = new ApplicationContext();

ctx.BeginTransaction();

. . .

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3. Align comments in consecutive lines

For multiple lines of code with trailing comments, align the comments so they willbe easy to read.

const MAX_ITEMS = 10; // maximum number of packets

const MASK = 0x1F; // mask bit TCP

Some developers use tabs to align comments, while others use spaces. Becausetab stops can vary among editors and IDEs, the best approach is to use spaces.

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4. Don´t insult the reader´s intelligence

Avoid obvious comments such as:

if (a == 5) // if a equals 5

counter = 0; // set the counter to zero

This wastes your time writing needless comments and distracts the reader with detailsthat can be easily deduced from the code.

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5. Be polite

Avoid rude comments like, “Notice the stupid user has entered a negative number,”

or “This fixes the side effect produced by the pathetically inept implementation of

the initial developer.” Such comments do not reflect well upon their author, and

you never know who may read these comments in the future: your boss, a

customer, or the pathetically inept developer you just insulted.

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6. Get to the point

Don’t write more in comments than is needed to convey the idea. Avoid ASCII art,

jokes, poetry and hyperverbosity. In short, keep the comments simple and direct.

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7. Use a consistent style

Some people believe that comments should be written so that non-programmers

can understand them. Others believe that comments should be directed at

developers only. In any event, as stated in Successful Strategies for Commenting

Code, what matters is that comments are consistent and always targeted to the

same audience. Personally, I doubt many non-developers will be reading code, so

comments should target other developers.

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8. Use special tags for internal use

When working on code as a team, adopt a consistent set of tags to communicateamong programmers. For example, many teams use a “TODO:” tag to indicate asection of code that requires additional work:

int Estimate(int x, int y)

{

// TODO: implement the calculations

return 0;

}

Tag comments don’t explain code; rather they seek attention or deliver amessage. But if you use this technique, remember to follow up and actually do whatthe message is asking.

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9. Comment code while writing it

Add comments while you write code and it’s fresh in your memory. If you leavecomments until the end, it will take you twice as long, if you do it at all. “I have notime to comment,” “I’m in a hurry,” and “The project is delayed” are all simplyexcuses to avoid documenting your code. Some developers believe you shouldwrite comments before code as a way to plan out your ultimate solution. Forexample:

public void ProcessOrder()

{

// Make sure the products are available

// Check that the customer is valid

// Send the order to the store

// Generate bill

}

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10. Write comments as if they were for you (in fact, they are)

When it comes to commenting code, think not only about the developers who willmaintain your code in the future, but also think about yourself. In the words of thegreat Phil Haack:

“As soon as a line of code is laid on the screen, you’re in maintenance mode on thatpiece of code.”

As a result, we ourselves will be the first beneficiaries (or victims) of our good (orbad) comments.

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11. Update comments when you update the code

There is no point in commenting correctly on code if the comments are not changed

with the code. Both code and comments must move in parallel, otherwise the

comments will actually make life more difficult for developers who maintain your

code. Pay special attention to refactoring tools that automatically update code but

leave comments unchanged and hence obsolete in the same instant.

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12. The golden rule of comments: readable code

One of the basic principles for many developers: Let your code speak for itself. Although onesuspects this movement is led by programmers who do not like to write comments, it is truethat self-explanatory code can go a long way toward making code that’s easier to understandand can even render comments unnecessary. For example, the code in my Fluid Interfacesarticle shows how clear self-explanatory code can be:

Calculator calc = new Calculator();

calc.Set(0);

calc.Add(10);

calc.Multiply(2);

calc.Subtract(4);

Console.WriteLine( "Result: {0}", calc.Get() );

In this example, comments are not needed and would likely violate tip #4. To facilitatereadable code, you might consider using proper names (as described in the classic Ottinger’sRules), ensure correct indentation, and adopt coding style guides. Failure to comply with thistip may result in comments that seem to apologize for bad code.

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13. Share these tips with your colleagues

Although tip #10 shows how we ourselves benefit immediately from good

comments, these tips will benefit all developers, especially in the context of team

working together. Therefore, feel free to share these commenting tips with your

colleagues to create code that is easier to understand and maintain.

Thank you!

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