![]() ![]() The value of these variables was taken from the parent scope. This time, we made our padding function anonymous and accessed $pad and $full_length with the help of the use keyword. We can rewrite the above code to use anonymous functions and the use keyword. We were also able to change the value of global $full_length inside our function. This is apparent from the output of parent_function(). When we use these variables inside our padding() function with the help of the global keyword, we are actually accessing the global values. However, they are not related to variables defined in the global scope because functions have their own scope in PHP. We define those two variables again inside the function parent_function(). They are part of the global scope when defined at the top. In the above example, we have defined the variables $pad and $full_length twice. Let's understand the difference between global and use with some examples: PHP also has a special use keyword that allows you to access variables from the parent scope inside an anonymous function. However, this approach has some disadvantages as it can make code maintenance harder in the long term. One way to access outside variables inside a function is to use the global keyword. Similarly, variables defined inside a function won't be accessible outside it. You cannot access variables defined somewhere else inside your functions. Basically, PHP has a global scope and a function-level scope. In one of our previous articles called Understanding Variable Scope in PHP, we covered variable scope in detail. Anonymous Functions Can Inherit Variables From the Parent Scope Here is an example:Īs you can see in the above code, these anonymous functions can be assigned to variables and called just like regular functions. After that, we can just call these functions using the variable name. One nice feature of anonymous functions is that we can assign them to variables or store them inside numerical or associative arrays. This can make it difficult for us to call them later if the need arises. However, anonymous functions don't have any names. This name is used to call the function later, whenever it is needed. We usually assign a name to any function that we define in PHP. Assigning Anonymous Functions to Variables Without anonymous functions, we would have to define this function somewhere else and come up with a non-colliding name. As you can see, it performs the trivial task of checking if a number is divisible by five. The second parameter to array_filter() is our callback function. In the code above, we simply return multiples of five from a given array of numbers. We can use both built-in and user-defined functions as callbacks. Callback functions are called by the main function to do a task based on logic you supply. One of the most common uses of anonymous functions is as callbacks. Implementing Callbacks With Anonymous Functions They are particularly helpful when you are dealing with functions that are only four to five lines long. These types of functions are called anonymous functions. In such cases, it is much easier to just place the function definition where it is needed, without worrying about coming up with a name for the function. Let's say you are working on a big project that requires you to write about 50 or more such functions. However, a function is sometimes required only in one place and nowhere else. This name is used to call the function at a later time whenever we need it. Whenever we define a function in PHP, we usually provide a name for it as well. You'll also learn about the newer arrow function syntax in PHP. This tutorial will teach you about the features and uses of anonymous functions in PHP. ![]()
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