Defining multiple namespaces in the same file

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- Defining multiple namespaces in the same file

## Defining multiple namespaces in the same file

(PHP 5 >= 5.3.0, PHP 7, PHP 8)

Multiple namespaces may also be declared in the same file. There are two allowed syntaxes.

Example #1 Declaring multiple namespaces, simple combination syntax

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

This syntax is not recommended for combining namespaces into a single file. Instead it is recommended to use the alternate bracketed syntax.

Example #2 Declaring multiple namespaces, bracketed syntax

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

It is strongly discouraged as a coding practice to combine multiple namespaces into the same file. The primary use case is to combine multiple PHP scripts into the same file.

To combine global non-namespaced code with namespaced code, only bracketed syntax is supported. Global code should be encased in a namespace statement with no namespace name as in:

Example #3 Declaring multiple namespaces and unnamespaced code

    <?phpnamespace MyProject {const CONNECT_OK = 1;class Connection { /* ... */ }function connect() { /* ... */  }}namespace { // global codesession_start();$a = MyProject\connect();echo MyProject\Connection::start();}?>

No PHP code may exist outside of the namespace brackets except for an opening declare statement.

Example #4 Declaring multiple namespaces and unnamespaced code

    <?phpdeclare(encoding='UTF-8');namespace MyProject {const CONNECT_OK = 1;class Connection { /* ... */ }function connect() { /* ... */  }}namespace { // global codesession_start();$a = MyProject\connect();echo MyProject\Connection::start();}?>