[REBOL] find/last/part behaviour
From: andreas::bolka::gmx::net at: 22-Dec-2002 1:53
I noted a quite odd behaviour of 'find when combining /last and /part
refinements - at least it is not what I expected.
Basically I wanted to achieve "ends with" functionality - some
examples to illustrate the desired behaviour:
ends-with? "1234567890" "890"
; == true
ends-with? "1234567890" "0"
; == true
ends-with? "1234567890" "9"
; == false
Now I thought that combining the /tail and /part refinements of 'find
would naturally map to this:
/part -- Limits the search to a given length or position.
range -- (Type: number series port)
/last -- Backwards from end of string.
/reverse -- Backwards from the current position
Silly me, it seems, as internal 'find priorities make /part limit the
string to be searched _first_ and then search backwards within that
string. Which leads to the following:
found? find/last/part "1234567890" "890" 3
; == false
If you agree that /part should have a "higher priority" than /last,
this behaviour is what would be desired.
However, there is a solution to achieve what was desired. Combine
/reverse and /part and use 'tail up-front:
found? find/reverse/part tail "1234567890" "890" 3
; == true
And it is this notion, that /reverse has a "higher priority" than
/part while /last has not, that I don't think is consistent. Any ideas
how this consistency problem could be resolved? Is it a problem at
all?
--
Best regards,
Andreas mailto:[andreas--bolka--gmx--net]
