Скачать или смотреть How to Properly Initialize Class Properties in PHP Without a Constructor

Discover the right way to initialize class properties in PHP without using constructors. A practical guide with a solution to common mistakes.
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This video is based on the question https://stackoverflow.com/q/72901974/ asked by the user 'WideWood' ( https://stackoverflow.com/u/11152224/ ) and on the answer https://stackoverflow.com/a/72902078/ provided by the user 'AterLux' ( https://stackoverflow.com/u/4931630/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding Class Property Initialization in PHP

Initializing properties in a PHP class is a foundational aspect of object-oriented programming. However, many developers encounter issues when they don’t use constructors to set up their class properties. If you’ve ever found that your class properties all hold the last value assigned to them, you’re not alone! In this post, we’ll explore the issue and how to effectively initialize properties in a PHP class without a constructor.

The Problem

Let’s say you have a simple class with a few properties representing views, URLs, and traffic. You choose to use setter methods to initialize these properties. However, upon setting values and then encoding them into a JSON response, you receive the same last value for all properties instead of the expected unique values.

Example Code

Here's what the starting point of your class might look like:

[[See Video to Reveal this Text or Code Snippet]]

When attempting to create an instance of this class and set values:

[[See Video to Reveal this Text or Code Snippet]]

Instead of obtaining a JSON output of {"views":44,"urls":55,"traffic":99999}, you receive {"views":99999,"urls":99999,"traffic":99999}. What went wrong?

The Cause of the Issue

The problem arises due to a small but critical mistake in how the properties are accessed within your setter methods. When you use $this->_views, this actually refers to a variable named _views, which resolves to an empty string in this context, leading to all properties being set to the last value assigned.

In simpler terms, writing $this->$_views mistakenly tries to access a variable variable, instead of the property itself.

Solution: Correcting the Property Access

To ensure that each setter correctly sets its corresponding property, you need to remove the dollar sign ($) from the property access. Adjust the assignment in your setter methods to look like this:

Corrected Code Example

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By addressing the way properties are accessed in your PHP class, you can effectively set and retrieve individual values without encountering unexpected behavior. Always remember that in PHP, when dealing with properties in classes, the syntax is critical.

Using the revised methods above, you will be able to successfully initialize properties and obtain the desired JSON output with distinct values for views, URLs, and traffic.

Happy coding!