Use variables to define an object or not?

Question

Recently watching some tutorials, I see programmers omitting the variables in code block. I don’t know what this practice is called, but I wonder if it is recommended, what are the advantages and disadvantages in its use, and if the way I put it is correct. The point is, it’s working...

Example:

$head = new MakeHead("Title");
    $head->_addmenu("180","./insert");
    $head->_addtoggle('190', 'toggle', 'bar');
$head->_printhead();

To:

(new MakeHead("Title"))
    ->_addmenu("180","./insert")
    ->_addtoggle('190', 'togglesearch', 'searchbar')
->_printhead();

Answer 1

The answer as always Depends.

Before deciding whether or not you need a variable you have to understand why you want the object. The goal of a variable is to store a reference to an object or value so that you can use it later, in this sense if there is no need to use it later you don’t need to store it in a variable (or constant).

In this example you gave we see a fluid interface, we give this name to classes whose methods return a reference of itself or a new instance of it, allowing to invoke a method upon the return of the method.

An example of this can be found in the PSR-7 specifications, where as you invoke the methods to build an http message (e.g. Request) you receive a new instance of that class and can chain calls.

This type of behavior is also common in the Builder project pattern, where a Builder returns to itself until a construction method (e.g. make, build or create) is called by returning what the Builder builds.

The main points where you don’t need to have a reference in a variable are:

• You will create the object only to call a method, e.g..

(new Logger("Startup"))->log("mensagem");

In this example we assume that we will not need this instance of logger after using it, if we needed we could store its reference in a variable.

• You will pass an object as a parameter once you create it.

$client->send(new User("João"));

In this example if the object is simple and the reading is not compromised you can instantiate the direct object in the method call.

An important point to remember is that you’re not programming for the computer to understand, you’re programming so that humans (you and whoever else is going to maintain this code) understand what’s been programmed, then you should try to make your code readable whenever possible, if it requires creating variables, create.

If you were making code for machines only you could name all your variables with varNumer, ex. var1, var2, var3, var4, etc., since the machine would understand, giving names that mean something is something we do so that we developers can understand what the program does with as little cognitive effort as possible.