On Mon, Aug 3, 2015 at 10:12 PM, Peter Stirling peter@pjstirling.plus.com wrote:
My read of the spec is that either behaviour is allowable.
The two behaviors are so different that I have a hard time accepting this.
I guess they didn't think about people using closures for initforms when they were drawing it up?
Yet they clearly thought about closures when they specified DEFCLASS[3] (see the part where processing of :initform form is mentioned). So, was this really just simple oversight?
To side-step the issue I would invoke a closure from the initform instead
(if that's how you want to do it).
This is indeed probably the proper workaround that would assure portability across CL implementation.
But I find sad that we'd have to force defstruct to be a top-level only form with this workaround instead of letting perfectly normal language constructs intermix freely as the problem would find appropriate and natural.
My interest here is that I am reworking the implementation of the DEFSTRUCT macro in MKCL. And honestly I am of the opinion that there is a pretty strong case to be made in favor of the clisp behavior on this issue. But I cannot figure out the justification for the other behavior illustrated by almost all of the other implementations. Is this just some long standing historical quirk at play here or is there really a reason for this way of doing it?
[3] http://www.lispworks.com/documentation/HyperSpec/Body/m_defcla.htm