[REBOL] Re: hash questions
From: rotenca:telvia:it at: 8-Jan-2002 21:00
Hi, Joel
> There are a number of "strange things" in the use of paths; using
> I don't understand the purpose of the inconsistencies:
>
> 1) when to generate an error vs. returning NONE to indicate
> data-not-found, and
I agree. It is documented, but i do not like it.
> 2) the fact that /: performs access-by-position or access-by-key
> depending on the type of the second word's value.
So we can end with:
>> x: 4
== 4
>> a/x
** Script Error: Invalid path value: x
** Where: do-boot
** Near: a/x
>> a/:x
== none
but neither 'x neither 4 are in block.
It is like the value was re-evaluated, like it was a refinement of the path
itself. Something of recursive evalutation of the get-word in the path:
>>a/:s
is re-evaluated like it was
>>a/value-of-s
if value-of-s is
integer or decimal (!) -> numeric offset
word -> word for select
BTW now i understand why the set-word value change the block:
>> a: [b 2]
== [b 2]
>> x: first [b:]
== b:
>> a/:x 3
== [b 3]
is like:
>> a/b: 3
== [b 3]
---
Ciao
Romano
