Version: 1.1.0

Automatic destruction

When a value is no longer used, Mojo destroys it. You write a destructor only when the struct owns a resource the compiler cannot see.

Essentials

• The last use is the destruction point.
• __del__(owned self) runs custom cleanup.
• Fields are destroyed after the destructor body.
• Copies and transfers decide which name runs the destructor.
• A collection destroys its elements.

Example

struct File:
    var handle: Int

    fn __del__(owned self):
        if self.handle != 0:
            close(self.handle)

Keep in mind

Do not call a destructor by hand on a type that Mojo already destroys. That frees the resource twice.