How to Retrieve Defined CONSTs in PHP Classes?

Constant Reflection: Retrieving Defined CONSTs in PHP Classes

In PHP, accessing CONSTs defined on classes can be challenging. The question arises: "Can I obtain a list of CONSTs associated with a particular class?"

Class and CONSTs

Consider the following class definition:

class Profile {
    const LABEL_FIRST_NAME = "First Name";
    const LABEL_LAST_NAME = "Last Name";
    const LABEL_COMPANY_NAME = "Company";
}

Reflection to the Rescue

While the standard PHP function get_defined_constants() cannot retrieve CONSTs defined on specific classes, the Reflection library provides a solution. Reflection allows us to gain information about classes and their properties.

To retrieve CONSTs, create a ReflectionClass object for the desired class:

$refl = new ReflectionClass('Profile');

Then, utilize the getConstants() method to obtain an array containing the defined CONSTs:

$constants = $refl->getConstants();

This array includes both the CONST names and values, allowing for flexible access and manipulation.

Example Output

Executing the code will produce the following output:

Array
(
    'LABEL_FIRST_NAME' => 'First Name',
    'LABEL_LAST_NAME' => 'Last Name',
    'LABEL_COMPANY_NAME' => 'Company'
)

Conclusion

By leveraging Reflection, PHP developers can easily retrieve CONSTs defined on classes, providing valuable insight and control over the class's functionality.

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