[REBOL] Re: Rebol interpreter bug with comparison of dates
From: al:bri:xtra at: 4-Dec-2002 16:24
Jan wrote:
> Personally, I don't mind such a behaviour, which disallows comparison of
apples to oranges. But I think the definition of (<) is too broad: it should
be more specific - narrowed down to the orderable things, such as numbers,
dates, but not points, etc. However, since the arguments of this operator
are untyped, the "help <" suggests that one can compare anything to
anything - and hence those unpleasant runtime surprises.
I prefer being able to compare any-value with any-value. I think it's more
versatile, as it enables one to write 'find -like functions that can find
values in a series and not have to type check first. Here's an example that
I was working on today (and where I found the problem):
Find-Range: function [Ranges [block!] Value [any-type!] /Strict] [Range] [
repeat Index length? Ranges compose [ ; 'Compose adds more
comparisons!
Range: Ranges/:Index
if all [Value >= Range/1 Value <= Range/2] [
return at Ranges Index
]
(
if not Strict [
[
if Value < Range/1 [
return at Ranges max 1 Index - 1
]
if all [
Value > Range/2
Index >= length? Ranges
] [
return at Ranges Index
]
]
]
)
]
]
; The following is normally in a separate file:
save %Term.r [; First and Last dates for each term.
[28/Jan/2002 28/Mar/2002]
[15/Apr/2002 28/Jun/2002]
[15/Jul/2002 20/Sep/2002]
[ 7/Oct/2002 6/Dec/2002]
]
Term: first Find-Range load %Term.r now/date
First_day_of_Term: first Term
Last_day_of_Term: last Term
Which finds the current (school) term for the current date (with allowance
for a date before or after the individual terms).
Andrew Martin
ICQ: 26227169 http://valley.150m.com/
