laravel-php Many frameworks import related classes directly through namespaces, but namespaces don't actually have that function? Explain it

Many PHP frameworks import related classes directly through namespaces, but namespaces don’t actually have that function? Please explain

Import a class using require_once include_once()...

But many frameworks, such as thinkphp, laravel, etc., do not use these methods, but use namespaces

What’s going on?

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Many PHP frameworks import related classes directly through namespaces, but namespaces don’t actually have that function? Please explain

Import a class using require_once include_once()...

But many frameworks, such as thinkphp, laravel, etc., do not use these methods, but use namespaces

What’s going on?

The other two answers mentioned some points, but they are not complete enough

First of all, this is the feature of automatic loading

Auto-loading was introduced in PHP5. You can use spl_autoload_register to register an auto-loading function. When PHP is looking for a class that does not exist in memory, it will call the auto-loading function registered in spl_autoload_register in turn. Find class

Another way that is also available but not good is to override the __autoload function, but then you can only have one autoloading function. If you also use some other libraries, it may cause some problems, so there is no need to do it. This is not recommended

As for composer, it comes with a standard autoload implementation. If you can make your code follow the directory organization of PSR, you can also directly use the autoload implementation provided by composer. You can simply learn about PSR

It should be noted that the auto-loading feature has nothing to do with namespaces. Although it is recommended to use it with namespaces, you will find in some old PHP codes that it is actually implemented using underscores _. The effect of namespace

Yes, but it is not written directly in the logic code. For your question, you can try searching for php automatic loading and composer automatic loading

You can check the usage of the namespace use. Use introduces classes, so there is no need for require_once include_once()...
In fact, use does not introduce the function, but it is introduced automatically when the program automatically loads the __autoload method. Related classes