PHP Operators: When to Use `::` vs. `->`?

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Understanding the Differences Between :: and -> Operators in PHP

Introduction:
PHP supports two distinct operators, :: (double colon) and -> (arrow), for accessing methods. This article aims to clarify the distinctions between these operators and their respective use cases.

Key Points:

• Operator Choice:

  • -> (Arrow): Used when the left operand refers to an object instance. Primarily employed for accessing instance members, although it can also be applied to static members.
  • :: (Double Colon): Typically used for scope resolution, where the left operand can be a class name, parent, self, or static. Usually applies to accessing static members.

Usage Guidelines:

Double Colon (::):

• Primarily used for static member access, such as accessing static variables or calling static methods.

• Can also be utilized to access instance members under specific conditions:

  • When the left operand is a parent class reference (parent::).
  • When the left operand is a self-reference (self::).
  • When the left operand is a called scope reference (static::), introduced in PHP 5.3.

Arrow (->):

• Exclusively used for accessing instance members.
• Can also be used to access static members, but this practice is discouraged.
• The assignment operator (=) is used to instantiate or modify variables, while the => operator is specifically used to assign data within arrays.

Additional Notes:

• An instance method call using :: is possible only if the targeted method is not declared as static and if a compatible object context exists.
• Static method calls using -> are permitted, but this approach is not recommended.

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