First-class callable syntax in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the first-class callable syntax in PHP?

It is a way to create a callable reference to a function or method using the syntax foo(...) or ClassName::methodName(...) that can be passed around like a variable.

beginner

How do you create a first-class callable for a named function <code>myFunction</code>?

Use $callable = myFunction(...); to get a callable reference to myFunction.

intermediate

How can you create a first-class callable for a static method <code>MyClass::myStaticMethod</code>?

Use $callable = MyClass::myStaticMethod(...); to get a callable reference to the static method.

intermediate

What is the benefit of using first-class callable syntax over traditional callables in PHP?

It is simpler and more readable. You can create callables without using strings or arrays, reducing errors and improving code clarity.

advanced

Can first-class callable syntax be used with closures (anonymous functions)?

No, first-class callable syntax is for named functions and methods. Closures are already callable objects and do not need this syntax.

Which syntax creates a first-class callable for a function named process?

A process(...)

B process()

C "process"

D ["process"]

The syntax process(...) creates a first-class callable reference to the function process.

How do you create a first-class callable for a static method Logger::log?

A Logger::log(...)

B Logger::log()

C [Logger, 'log']

D "Logger::log"

Using Logger::log(...) creates a first-class callable for the static method.

What does the ... (splat operator) do in first-class callable syntax?

A Calls the function immediately

B Indicates a callable reference

C Creates an array

D Unpacks arguments

In this context, ... after the function name indicates creating a callable reference, not calling it.

Can you use first-class callable syntax with anonymous functions (closures)?

A Yes, but only with named closures

B Yes, with <code>closure(...)</code>

C No, closures cannot be called

D No, closures are already callable objects

Closures are already callable objects, so first-class callable syntax is not needed for them.

What is a key advantage of first-class callable syntax in PHP?

A Automatically executes functions

B Replaces all function calls

C Simplifies creating callable references

D Only works with static methods

It simplifies creating callable references, making code easier to read and less error-prone.

Explain how to create a first-class callable for a named function and a static method in PHP.

Think about how you write the function or method name followed by three dots.

Describe the benefits of using first-class callable syntax compared to traditional callables in PHP.

Focus on how the new syntax makes code easier to write and understand.