[REBOL] [subject: error and trial]
From: rebol665:ifrance at: 4-Mar-2002 22:54
Hi rebollers,
I am coming again with a question posted on November the 23th 2001. At the
time, I thought I had understood Ladislav's answer, but the truth is I am
not so sure.
All began while reading Ladislav's contexts.html...
There are Words that do not have the ability to refer to Rebol values. We
can call them undefined Words. [ ...] This function can be used to find out,
if a Word is undefined:
undefined?: func [
{determines, if a word is undefined}
word [any-word!]
] [
error? try [error? get/any :word]
]
My question was "why use error? two times?". In my eyes, a more simple
version of the function could be :
u-def?: func [
{determines, if a word is undefined}
word [any-word!]
] [
error? try [get/any :word]
]
We can test these two functions whith Ladislav's own example of an undefined
word.
a-word: first first rebol/words ;== end!
>> undefined? a-word
== true
>> u-def? a-word
== true
>> undefined? 'print
== false
>> u-def? 'print
== false
I am not pretending I am right, because I must be wrong! but I deeply need
to understand where and why !
Patrick
PS: this message has been posted twice because I realized that I did not use
the right "from" (the one who is listed) for the first one. You should
receive this one first if I am not wrong (again).
