Re: properties

[Neil Jerram]

>>>>> "Dirk" == Dirk Herrmann <address@hidden> writes:

    Dirk> Hi Neil, I noticed that you have done some work with source
    Dirk> properties.  Without having looked into details yet, I would
    Dirk> like to remark that there is a 'central' mechanism for all
    Dirk> kinds of properties, which is IMO quite nice.  If I remember
    Dirk> correctly, there was once a plan to get rid of all
    Dirk> 'specialized' properties in guile and use this common
    Dirk> mechanism instead.  I also seem to remember that there were
    Dirk> some arguments against such a step, because the 'central'
    Dirk> properties mechanism would be somewhat slower.  However, I
    Dirk> suggest to take a close look before introducing or extending
    Dirk> any specialized property features (as source properties are)
    Dirk> in guile.

Thanks, Dirk.  You're right to point this out, and I did wonder about
it before making my change.  I would say that the change I made is
more a bug fix than an extension, but the point is debatable as one
could argue that source properties shouldn't try to support anything
other than the few properties that are handled explicitly in the
SRCPROPS object.

In any case, I'm quite happy to reverse my change if you (and others)
think that would be best.  srcprop.c really needs review and
consideration as a whole, as you say.

        Neil

PS. The thing that really makes source properties more special than
general properties, as currently implemented, is that they are copied
by cons-source (and copy-tree) as source expressions are transformed
and memoized.  This is useful to some extent for a debugger.

If we merged source properties into the more general mechanism, and
could still achieve satisfactory performance, we could perhaps
generalize cons-source so that it copied all object properties.