phpDocumentor

What is a DocBlock?

Overview

The goal of this tutorial is to introduce you to writing and subsequently generating effective documentation with phpDocumentor.

Writing a DocBlock

A DocBlock is a piece of documentation in your source code that informs you what the function of a certain class, method or other Structural Element is.

What can be documented in your source code?

Before we discuss what a DocBlock looks like, let's first zoom in on what you can document with them. phpDocumentor follows the PHPDoc definition and recognizes the following Structural Elements:

In addition to the above, the PHPDoc standard also supports DocBlocks for Files and include/require statements, even though PHP itself does recognize this as a language structure.

Each of these elements can have exactly one DocBlock associated with it, which directly precedes it. No code or comments may be between a DocBlock and the start of an element's definition.

What does a DocBlock look like?

DocBlocks are always enclosed in a particular comment-type, called a DocComment. A DocComment starts with /** (opener) and ends with */ (closer). Each line in between the DocComment opener and its closer should start with an asterisk (*).

For example:

<?php
/**
 * This is a DocBlock.
 */
function associatedFunction()
{
}

**File-level DocBlocks**

Quite often projects will also want to document the license or role for an entire file.
This can be accomplished by having a DocBlock as the first element encountered in a file.
It is important to note that whenever another *Structural Element* directly follows the DocBlock,
it is no longer recognized as a File-level DocBlock, but as belonging to the subsequent element.

The following DocBlock is a File-level DocBlock:

.. code:: php

   <?php
   /**
    * I belong to a file
    */

   /**
    * I belong to a class
    */
   class Def
   {
   }

In contrast, in the following example the DocBlock belongs to the class:

.. code-block:: php

   <?php
   /**
    * I belong to a class
    */

   class Def
   {
   }

DocBlocks are divided into three parts. Each of these parts is optional, except that the Description can not exist without a Summary.

Summary

The Summary, sometimes called a short description, provides a brief introduction into the function of the associated element. A Summary ends when it encounters either of the below situations:

- a period ., followed by a line break - or a blank (comment) line.

Description
The Description, sometimes called the long description, can provide more information. Examples of additional information are: a description of a function's algorithm, a usage example or a description of how a class fits in the whole of the application's architecture. The description ends when the first tag is encountered on a new line or when the DocBlock is closed.
Tags and Annotations
These provide a way to succinctly and uniformly provide meta-information about the associated element. Tags can, for example, describe the type of information that is returned by a method or function. Each tag is preceded by an at-sign (@) and starts on a new line.

Example

A DocBlock looks like this:

<?php
/**
 * A summary informing the user what the associated element does.
 *
 * A *description*, that can span multiple lines, to go _in-depth_ into
 * the details of this element and to provide some background information
 * or textual references.
 *
 * @param string $myArgument With a *description* of this argument,
 *                           these may also span multiple lines.
 *
 * @return void
 */
 function myFunction($myArgument)
 {
 }

Let's go through this example line by line and discuss which is which,

Line 2:
shows that a DocBlock starts with the opening sequence /**.
Line 3:
has an example of a Summary. This is, usually, a single line but may cover multiple lines as long as the end of the summary, as defined in the previous chapter, is not reached.
Line 5, 6 and 7:
show an example of a Description, which may span multiple lines and can be formatted using the Markdown markup language. Using Markdown you can make text bold, italic, add numbered lists and even provide code examples.
Line 9 and 12:
show that you can include Tag reference in your DocBlocks to provide additional information about the succeeding element. In this example, we declare that the argument $myArgument is of type string, with a description what this argument represents, and we declare that the return value for this method is void, which means that no value will be returned.
Line 13:
shows the closing sequence */, which is the same as that for a multi-line comment (/* .. */).

If you'd like to know more about what DocBlocks do for you, visit the chapter More on DocBlocks for more in-depth information.

Read more

  • Generating documentation, now that you have learned what a DocBlock looks like, shall we take phpDocumentor for a spin?
  • Configuration, there are a lot more options to phpDocumentor. To maintain consistent documentation, it is good practice to define them all in a configuration file and to include that in your project.
  • Running phpDocumentor, if you'd like to know more on the options available when using phpDocumentor; see the guide for more information.

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