On Sat, May 7, 2011 at 3:12 AM, Zhe Hu <iammegat...@gmail.com> wrote:
> what's the difference between:
> V{ } clone 3 suffix!
> V{ } 3 suffix!
> I guess my question is why do we need "clone", since it takes one object,
> but puts back just one object.
V{ } creates a literal vector and pushes it on the stack. When typing
at the listener this doesn't make much difference from using 'clone'
with it. But when used in a function it makes a big difference. Try
this:
: my-vec ( -- v ) V{ } ;
: my-vec2 ( -- v ) V{ } clone ;
my-vec 3 suffix! drop my-vec .
my-vec2 3 suffix! drop my-vec2 .
The V{ } creates a new vector and embeds that actual vector instance
in the function body. So the '3 suffix!' on my-vec actually modifies
the vector in the function body. Calling my-vec again shows the
modified vector.
Chris.
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