The module macro is used to annotate the get_module function, which is used by the PHP interpreter to retrieve information about your extension, including the name, version, functions and extra initialization functions. Regardless if you use this macro, your extension requires a extern "C" fn get_module() so that PHP can get this information.

Using the macro, any functions annotated with the php_function macro will be automatically registered with the extension in this function. If you have defined any constants or classes with their corresponding macros, a 'module startup' function will also be generated if it has not already been defined.

Automatically registering these functions requires you to define the module function after all other functions have been registered, as macros are expanded in-order, therefore this macro will not know that other functions have been used after.

The function is renamed to get_module if you have used another name. The function is passed an instance of ModuleBuilder which allows you to register the following (if required):

  • Extension and request startup and shutdown functions.
    • Read more about the PHP extension lifecycle here.
  • PHP extension information function
    • Used by the phpinfo() function to get information about your extension.
  • Functions not automatically registered

Classes and constants are not registered in the get_module function. These are registered inside the extension startup function.


#![cfg_attr(windows, feature(abi_vectorcall))]
extern crate ext_php_rs;
use ext_php_rs::prelude::*;
use ext_php_rs::{info_table_start, info_table_row, info_table_end};
use ext_php_rs::php::module::ModuleEntry;
/// Used by the `phpinfo()` function and when you run `php -i`.
/// This will probably be simplified with another macro eventually!
pub extern "C" fn php_module_info(_module: *mut ModuleEntry) {
    info_table_row!("my extension", "enabled");

pub fn get_module(module: ModuleBuilder) -> ModuleBuilder {