[REBOL] Re: Block member as a mutable variable (question)
From: carl:cybercraft at: 11-Sep-2001 19:10
Hi Tim - Carl here again...
On 11-Sep-01, Tim Johnson wrote:
> I have a nested block as such:
> file-block: [[0 ["recno" "integer"] ["name" "string"]
> ["country" "string"] ["speed" "integer"] ["range"
> "integer"]]] I set a word to the numeric value like this:
>>> test: first first file-block
> == 0
> Then I increment test:
>>> test: test + 1
> == 1
> <sigh>but</sigh> I don't get the results I want.
>>> file-block
> == [[0 ["recno" "integer"] ["name" "string"] ["country" "string"]
> ["speed" "integer"] ["range" "integer"]]]
> Alas! I was hoping that I would see a '1 as first first 'file-block
> What have I left out here?
Integers aren't mutable, and you'll find that your test variable is an
integer and not a reference to a value in file-block (which I think
is what you expected?) My approach would be...
>> test: first file-block
== [0 ["recno" "integer"] ["name" "string"]
["country" "string"] ["speed" "integer"] ["range" "integer"]]
>> change test 1 + first test
== [["recno" "integer"] ["name" "string"]
["country" "string"] ["speed" "integer"] ["range" "integer"]]
>> test
== [1 ["recno" "integer"] ["name" "string"]
["country" "string"] ["speed" "integer"] ["range" "integer"]]
The above looks a bit back-to-front, but...
change test first test + 1
gives an error, though you could use...
change test test/1 + 1
which is perhaps the nicest.
Hope that helps.
> TIA
> Tim
--
Carl Read
