Re: Using :type slot option

For those who might be interested. 
Here is an updated version for the slot type verification code. 
It only relies on using a metaclass and LispWorks :optimize-slot-access, if one wants to verify slot accessors. 
Bruno


> On Feb 18, 2025, at 11:44, Bruno Emond <[email protected]> wrote:
> 
> I understand that the Common Lisp standard specifies that "The consequences of attempting to store in a slot a value that does not satisfy the type of the slot are undefined.”. 
> 
> However, I am wondering if there is a simpler way to implement slot type checking than the code I wrote (see file attached). 
> 
> A small annoyance with this code is that one need to always include:
> 	1) inheritance to a class that verify slot types when an instance is initialized (however this can be done once for the most general class), 
> 	2) the metaclass option to verify a slot type when the slot value is set, and possibly (has to be done for every class definition), 
> 	3) the class option :optimize-slot-access nil (has to be done for every class definition), if one also wants to verify the type of a slot when it is set using an accessor.
> 
> Thanks for any suggestions. 
> 
> Bruno
> 
> <typep-slots.lisp>