[REBOL] Re: Re(2): Setting Block Data
From: ingo:2b1 at: 29-Nov-2000 11:37
Hi Anton,
let's step through it:
REBOL/Core 2.4.37.4.2 30-Oct-2000
Copyright 2000 REBOL Technologies. All rights reserved.
>> ; set some values
>> info: [db [[detail "detail one"] [detail "detail two"]]]
== [db [[detail "detail one"] [detail "detail two"]]]
>> a: "info db 1 detail"
== "info db 1 detail"
>> v: #"q"
== #"q"
; now try what happens
>> probe to-set-path a v
info/db/1/detail:
== #"q"
>> reduce [to-set-path a v]
== [info/db/1/detail: #"q"]
>> form reduce [to-set-path a v]
== "info/db/1/detail: q"
>> do form reduce [to-set-path a v]
; here rebol says goodbye, have you spotted the problem ???
Here the last 3 lines again:
>> form reduce [to-set-path a v]
== "info/db/1/detail: q"
>> do form reduce [to-set-path a v]
; !!! form has formed #"q" to just "q", so when the
; is 'DOne in the next line, the path will be set to
; the value returned by the function 'q which happens
; to shutdown the interpreter ...
; A working version would be:
do bind reduce [to-set-path a v] 'info
; 'do can do the block
; 'bind is needed, so that the block is evaluated in the right
; context ....
; And to write the corresponding function set-path is left to the
; reader (meaning, I don't know how to do it best, either ;-)
I hope that clarifies it a bit ...
kind regards,
Ingo
Once upon a time Anton spoketh thus:
