控制器方法中的参数顺序

Question

Suppose we have the following route in Laravel:

Route::get('/blog/{id}/{slug}', ['as' => 'blog', 'uses' => 'Front\PostController@single']);

Where the <kbd>{id}</kbd> and the <kbd>{slug}</kbd> are variables and will be passed as arguments to single() method of PostController class as below:

public function single($id, $slug) {}

But you can also pass the Request object as well, like so:

public function single(Request $request, $id, $slug) {}

or even:

public function single($id, $slug, Request $request) {}

and the Laravel still can handle them fine... looks like the order of arguments does not metter or there is some special technique applied?

Answer 1

The order of the arguments is not important except if you use a default value in those arguments (available since PHP 5.6+), like this:

function something($foo, $bar=true) { ... }

Which should be the last ones in the arguments.

Please check the official PHP docs about "use of default parameters in functions":

The default value must be a constant expression, not (for example) a variable, a class member or a function call.

Note that when using default arguments, any defaults should be on the right side of any non-default arguments; otherwise, things will not work as expected.