What is the php namespace child namespace?

In the previous article, we learned about namespaces and how to define namespaces. If necessary, please read "php namespace: How to define space?" 》. This time we introduce sub-namespaces to you, you can refer to them if necessary.

In PHP, namespaces can help us do many things. We can prevent the names we define from conflicting with PHP internal names, and we can also give the identifier a shorter name to make it easier for us to use and read.

And it also has an important function, but let us look at a small example first, and then we will talk about what this function is.

<?php
namespace MyProject\Sub\Level;  //声明分层次的单个命名空间

const CONNECT_OK = 1;
class Connection { /* ... */ }
function Connect() { /* ... */  }

?>

Let’s take a look at this and then look at the namespace in the previous article.

<?php
namespace MyProject {
    const CONNECT_OK = 1;
    class Connection { /* ... */ }
    function connect() { /* ... */  }
}

namespace AnotherProject {
    const CONNECT_OK = 1;
    class Connection { /* ... */ }
    function connect() { /* ... */  }
}
?>

Compare it carefully. Do you find any differences?

Let us shift our attention to <strong>namespace</strong>. Are the words a little different? In the above example, there are "\#" between words. ##", and the following is just one word. Everyone can see it.

This is another function of it, sub-namespace. Subnamespaces are similar to directories and files, and PHP namespaces also allow us to specify the name of a hierarchical namespace. Therefore, the name of the namespace can also be defined in a hierarchical manner.

Based on our current understanding of sub-namespaces, let's look at the example. We can see that in the first php statement, we define three designated hierarchical namespaces, which are constants.

MyProject\Sub\Level\CONNECT_OK, class MyProject\Sub\Level\Connection and function MyProject\Sub\Level\Connect.

In this way we can find content through different layers to facilitate our understanding.

That’s all. If you want to know anything else, you can click here. → →

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