Conditional Moose::Role consumption

I have a Moose class, that is consuming a Role like ...

package MyPackage;
use Moose;

with 'MyRole';

# ...

__PACKAGE__->meta->make_immutable;

My goal is, to only use a role, when another module is installed on the running system without creating a new dependency in my modules. When the module is not available the normal package functionality should be used, without the role and without crashing.

I already found ensure_all_roles and apply_all_roles in Moose::Util. I tried to write a method, that calls them when my conditions are fulfilled. But since I want my class to be immutable, the application crashes...

The 'add_package_symbol' method cannot be called on an immutable instance

That makes sense to me.

My question is: How to apply a role under a given condition for a class, that is marked as immutable?

Solution

I tried the following

with 'MyRole' if $condition;

It works without errors for both truth values of $condition.