feat: Add doc about interface in guide

Author: Norbytus

guide/src/SUMMARY.md

@@ -27,6 +27,7 @@
 - [Macros](./macros/index.md)
   - [Module](./macros/module.md)
   - [Function](./macros/function.md)
+  - [Interfaces](./macros/interface.md)
   - [Classes](./macros/classes.md)
     - [`impl`s](./macros/impl.md)
   - [Constants](./macros/constant.md)

guide/src/macros/index.md

@@ -13,6 +13,7 @@ used from PHP without fiddling around with zvals.
   methods and constants.
 - [`php_const`] - Used to export a Rust constant to PHP as a global constant.
 - [`php_extern`] - Attribute used to annotate `extern` blocks which are deemed as
+- [`php_interface`] - Attribute used to export Rust Trait to PHP interface
   PHP functions.
 - [`php`] - Used to modify the default behavior of the above macros. This is a
     generic attribute that can be used on most of the above macros.
@@ -23,4 +24,5 @@ used from PHP without fiddling around with zvals.
 [`php_impl`]: ./impl.md
 [`php_const`]: ./constant.md
 [`php_extern`]: ./extern.md
+[`php_interface`]: ./interface.md
 [`php`]: ./php.md

guide/src/macros/interface.md

@@ -0,0 +1,73 @@
+# `#[php_interface]` Attribute
+
+You can export an entire `Trait` block to PHP. This exports all methods as well
+as constants to PHP on the interface. Trait method SHOULD NOT contain default implementation
+
+## Options
+
+By default all constants are renamed to `UPPER_CASE` and all methods are renamed to
+camelCase. This can be changed by passing the `change_method_case` and
+`change_constant_case` as `#[php]` attributes on the `impl` block. The options are:
+
+- `#[php(change_method_case = "snake_case")]` - Renames the method to snake case.
+- `#[php(change_constant_case = "snake_case")]` - Renames the constant to snake case.
+
+See the [`name` and `change_case`](./php.md#name-and-change_case) section for a list of all
+available cases.
+
+## Methods
+
+See the [php_impl](./impl.md#)
+
+## Constants
+
+See the [php_impl](./impl.md#)
+
+## Example
+
+Define trait example with few methods and constant, and try implement this interface
+in php
+
+```rust,no_run
+# #![cfg_attr(windows, feature(abi_vectorcall))]
+# extern crate ext_php_rs;
+use ext_php_rs::{prelude::*, types::ZendClassObject};
+
+
+#[php_interface]
+#[php(name = "Rust\\TestInterface")]
+trait Test {
+    const TEST: &'static str = "TEST";
+
+    fn co();
+
+    #[php(defaults(value = 0))]
+    fn set_value(&mut self, value: i32);
+}
+
+#[php_module]
+pub fn module(module: ModuleBuilder) -> ModuleBuilder {
+    module
+        .interface::<PhpInterfaceTest>()
+}
+
+# fn main() {}
+```
+
+Using our newly created interface in PHP:
+
+```php
+<?php
+
+assert(interface_exists("Rust\TestInterface"));
+
+class B implements Rust\TestInterface {
+
+    public static function co() {}
+
+    public function setValue(?int $value = 0) {
+
+    }
+}
+
+```

tests/src/integration/interface/interface.php

@@ -9,10 +9,6 @@
 
 final class Test extends Exception implements ExtPhpRs\Interface\EmptyObjectInterface
 {
-    public function __construct()
-    {
-    }
-
 	public static function void(): void
 	{
 	}