[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Constructor rationale questions

This page is part of the web mail archives of SRFI 76 from before July 7th, 2015. The new archives for SRFI 76 contain all messages, not just those from before July 7th, 2015.

Andre van Tonder <andre@xxxxxxxxxxxxxxxxx> writes:

Andre van Tonder <andre@xxxxxxxxxxxxxxxxx> writes:

> "If the custom field initialization were omitted, it would still be possible to 
> perform custom initialization by writing a separate constructor procedure, which 
> would wrap a record type's actual constructor. 
> [...]
> I have not read the reference implementations in detail, but presumably they 
> construct the syntactic layer on top of the procedural substrate.  Yet the 
> procedural substrate makes no reference to a custom constructor.  Doesn't this 
> contradict the last line above by showing that you can build a layer that allows 
> extensions with access to custom constructors from a layer that doesn't store 
> custom constructors?

Yes, but you misunderstand the sentence in the draft: It's not saying

"If ..., it would still be possible to <something>.  However, we want
to make <something> impossible."

Instead, the sentence is trying to say: "If the construction procedure
was defined outside the DEFINE-TYPE, it wouldn't be available through
the type defined by DEFINE-TYPE, and we couldn't use it, say, through
the PARENT clause."

Would this be a better wording?

Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla