From: David Alan Black <dblack@...>
Date: 2001-09-09T06:02:59+09:00
Subject: [ruby-talk:21016] Re: length of Ruby array from C?

Hello --

On Sun, 9 Sep 2001, Neil Conway wrote:

> > > 2) clumsy: if this is the only way to get the length, could we perhaps
> > > have some syntactic sugar? For instance, a function (or macro)
> > > rb_ary_length(VALUE), which returns the length of the specified array as
> > > a C integer. Since this is a relatively common operation, I think it
> > > would be worthwhile to make it a bit easier for extension writers.
> >
> > I think that would be sort of unwieldy, since you'd have to have
> > rb_ary_xxxx(VALUE), rb_string_xxxx(VALUE), etc., to replace the
> > current way of doing it by accessing C structure members.
>
> I still think this would be a good idea. Of the builtin structs,
> 'length' only makes sense for RArray and RString. You _could_ add
> functions for RRegexp, RBigNum and RStruct, but since these are
> relatively rarely used (compared to RArray and RString), there would be
> no need to define more than 2 functions -- rb_ary_len(VALUE) and
> rb_str_len(VALUE). That's not too unwieldy, IMHO; and I find
> "rb_ary_len(ary)" to be more readable than "RARRAY(ary)->len". It also
> prevents extension writers from (directly) accessing the fiels of those
> structures, which is generally a bad idea (as README.EXT points out).

Well, *changing* them is a bad idea :-)  But just reading them is
such a common thing throughout the source -- not just len, but
ptr, super, iv_tbl, etc.  It feels (to me) like it would be inconsistent
to change the interface for just one property of just two types.


David

-- 
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav