Why Do Some PHP Class Methods Have a Leading Underscore?

What's the deal with a leading underscore in PHP class methods?

PHP developers prefix some class methods with a single underscore, such as _foo(), instead of foo(). While it's ultimately a personal preference, this technique has roots in PHP 4.

Before OOP was introduced in PHP 4, there were no protected or private methods. Developers prefaced methods intended to be with an underscore to discourage external access. The convention is similar to the syntax in other languages. In older classes, developers sometimes annotated methods with /***/ __foo().

It's important to note that not all methods starting with an underscore are meant to be . Over time, some developers may have extended the convention to differentiate between internal and external methods. However, this is not a standard practice and has led to confusion.

In modern PHP, it's best to use the proper visibility modifiers (public, protected, ) to define method accessibility. The presence of a leading underscore alone should not be interpreted as a restriction on method use.

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