idioms dtor-finally should use "defer" library instead

[bigdogs]

The sample code in idioms dtor-finally cannot capture outside variable, which means it's useless in most cases

[MarcoIeni]

Sorry, I don't understand, can you provide an example or something like that, please? :)

[Kushagra-0801]

@bigdogs the struct in the sample code is a unit struct. You could have fields in there too. In the worst case, you can just store a Boxed closure and execute it in the drop impl.