This chapter covers inline code commenting in more detail. Inline comments are all comments not included in doc blocs. The goal of in line commenting is to explain code in context. Such explanation may take many different forms.

Comments that are written in a readable and narrative style, especially when explaining a complex process, are encouraged. In general they should be placed close to the code explained rather than before the entire block of code.

Comments should be as sentence like as possible, which is to say that they should be complete and readable, not in short hand.

Comments are not a replacement for detailed doc blocks. Comments serve to explain the logic and structure of code itself rather than the use of code.

Formatting of Comments

Comment blocks that introduce large sections of code and are more than 2 lines long should use /* */ (C) style and should use * on each line with the same space/tab rules as doc blocks. If you need a large introduction consider whether this block should be separated into a method to reduce complexity and therefore providing a full docblock.

Comments should precede the code they refer to. As a corollary, comments should not be on the same line as the code to which they refer (which puts them after the code they reference). They should be on their own lines.

Don’t use a blank line between comments and the code they refer to (no space underneath a comment block).

Always have a single blank line before a comment or block of comments unless the comment (or block) is at the beginning of a code structure. ( You should not have a blank line after a '{' line )

For example in the following case there is no new line before the first comment (because it follows a '{' line) but we do want a new line before the second comment:

while (!$done)
	// We don't want an infinite loop here.
	$done = true;
// Now let's do something interesting.
$result = somethingInteresting();

Comments should align with the code they refer to, using the same indenting as the line that follows the comment.

Comments should be indented with tabs (like code, not like doc blocks).

Content of comments

Comments should use en-GB

Always have a space between // and the start of comment text.

New lines should always start with an upper case letter unless:

  • The line is a continuation of a complete sentence.
  • The term is code and is case sensitive.

Code that is included specifically to assure compatibility with other software (for example specific browsers or a specific version of the CMS or for backward compatibility reasons) should be clearly marked as such. If there is the intention to remove specific code at a future point, state that but do not use a deprecation tag or specify a release (this can be hard to predict).

Check spelling and grammar on all comments (see below and the en-GB guidelines).

Only end a line with a period if it is a full sentence.

Rather than use docblock tags use See:, Link: and Note: for comments if appropriate.

Do not use HTML in comments unless specifically related to the comment content.

Do not leave commented code unless there is a clearly explained reason for doing so. In such a case, a comment saying "Code intentionally commented" will prevent accidental removal.

Comments may include forward looking statements of how something will be extended or modified in the future, but not todos indicating that code is not complete or ready to use.

Remember that humor and sarcasm are difficult to translate.


Capitalise all letters of acronyms such as HTML, XML, SQL, GMT, and UTC.

Common spelling and grammar errors for which to check.

Joomla contributors include many non-native speakers of en-GB which makes it understandable that there are sometimes spelling and grammar errors. At the same time, some people reading comments also are non native speakers and may even use automated translation to understand comments. This makes it very important that comments should follow proper en-GB spelling and grammar rules. Unfortunately, these can be tricky.

S vs Z

en-GB most commonly uses ise where en-US would use ize, such as normalise instead of normalize. (Note that there are some exceptions to this rule.)

Use of apostrophes is one of the trickier parts of English.

Lets versus let’s

Lets means permits or allows to:

// This lets the user enter data

Let’s is a contraction for let us and means we are going to do this now:

// Let's validate the field

Its versus it’s

Its is the possessive form of it:

// Get its ID

It’s is a contraction of it is

// It's time to save

The correct Joomla spelling of some commonly used words.

  • dependant
  • deprecated