[REBOL] Re: Bug! in assignment to date! values with stacked set-path values
From: rotenca:telvia:it at: 18-Nov-2002 22:40
Hi Gabriele
> I agree with Ladislav.
Gabriele, you bypass Load for this, i was speaking of Load. And my observation
is still valid, also a set-path can be used like a path by the interpreter if
it find a function along the path. Now i'm thinking that the problem is all in
function refinement, see my previous message.
> In particular:
>
> >> f: func [/ref] [1]
> >> p: to path! [f ref]
> == f/ref
> >> do reduce [p]
> == 1
> >> p: to path! [f ref:]
> == f/ref:
> >> do reduce [p]
> == 1
> >> p: to set-path! [f ref:]
> == f/ref::
> >> do reduce [p]
> == 1
This is what i point: no set action at all, the interpreter does not care
about the fact the that path is a set-path!
> >> p: to set-path! [f ref]
> == f/ref:
> >> do reduce [p]
> == 1
> which shows that REBOL is just being very permissive for functions
> with refinements.
At least.
> I think that for both set-path! and path!, first of all REBOL
> determines the value of the first word. Then, it "decodes" the
> path up until the last value, and then it decides what to do based
> on the type of the path. Probably, as soon as it finds out that
> the first word refers to a function!, it passes the control to the
> code handling functions, that simply does not "know" about
> set-path!s and so behaves like it was a path!.
Yes you are right and this is what i want to point. I did not want to say that
set-path does not exists in absolute, but that in some situations it is like a
path. I could make an example: a block which, if at some point contains the
word list!, start to behaviour like a list!. Only in this sense i said that it
is not a true datatype!.
> RPT> Often I'm asking myself: what are advantages of refinements in
functions?
> Economy of expression. Without refinements, using functions like
> OPEN would require a lot of arguments.
open: func [file type [integer!]][
if type and 1 [ ;direct]
if type and 2 [ ;no-wait]
if type and 4 [ ;binary]
or
open: func [file type [block!]][
if find type 'direct [ ;direct]
if find type 'no-wait [ ;no-wait]
if find type 'binary [ ;binary]
> Also, one could not extend
> functions retaining compatibility like it was done with MOLD (/ALL
> refinement) or LOAD (/LIBRARY refinement) etc.
You are right. Also because any-type! cannot help for backward compatibility.
---
Ciao
Romano
