Range oddness?

ruby-talk
1

Hi all,
I’m trying to implement simple range check for my admin module …
and I found strange thing/behaviour:

$ ruby -e ‘p Range.new(1,4).type’
Range
$ ruby -e ‘p (1…4).type’
1…4

Well, what’s wrong with the latter?

The ‘real’ problem for me is that:

``

UID_RNG = (99…65000)

raise ArgumentError, “UID #{uid} out of allowed range”
unless UID_RNG.include?(uid)

‘’

raises exception for ‘uid = 997’

Thanks in advance,
W.

PS:

$ ruby -v
ruby 1.6.7 (2002-06-30) [i686-linux]

···

–
Wejn <lists+rubytalk(at)box.cz>
(svamberk.net’s Linux section, fi.muni.cz student, linuxfan)

    Bored?  Want hours of entertainment?         <<<
      Just set the initdefault to 6!             <<<
2

The ‘real’ problem for me is that:
[…]
raises exception for ‘uid = 997’

Well, my real problem is that I’m just heedless … uid = “997”, just
because it comes from ARGV :frowning:

But the ‘p (1…4).type # => (1…4)’ remains mystery for me …

W.

···

–
Wejn <lists+rubytalk(at)box.cz>
(svamberk.net’s Linux section, fi.muni.cz student, linuxfan)

    Bored?  Want hours of entertainment?         <<<
      Just set the initdefault to 6!             <<<
3

Wejn wrote:

$ ruby -e ‘p Range.new(1,4).type’
Range
$ ruby -e ‘p (1…4).type’
1…4

Well, what’s wrong with the latter?

It appears to be an issue of precedence. Typing this in irb, I get:
irb(main):001:0> p (1…4).type
1…4
NilClass
…suggesting that the type call binds to the result of the p call. This
works as expected on 1.7.2, but you really should write it
p((1…4).type) to remove ambiguity.

raises exception for ‘uid = 997’
…
$ ruby -v
ruby 1.6.7 (2002-06-30) [i686-linux]

Unable to reproduce this problem on both
ruby 1.6.6 (2001-12-26) [i586-linux-gnu] and
ruby 1.7.2 (2002-07-13) [i686-linux] so I can’t help you on that one,
sorry…

···

–
([ Kent Dahl ]/)_ ~ [ http://www.stud.ntnu.no/~kentda/ ]/~
))_student/(( _d L b_/ NTNU - graduate engineering - 4. year )
( __õ|õ// ) )Industrial economics and technological management(
_/ö____/ (_engineering.discipline=Computer::Technology)

4

Hi –

The ‘real’ problem for me is that:
[…]
raises exception for ‘uid = 997’

Well, my real problem is that I’m just heedless … uid = “997”, just
because it comes from ARGV :frowning:

But the ‘p (1…4).type # => (1…4)’ remains mystery for me …

What’s happening is that it’s being parsed as:

(p (1…4)).type

So the ‘p’ part happens (you see (1…4)), and .type is evaluated
silently.

I have to say I haven’t gotten the hang of exactly how/when/why Ruby
does one thing and not the other. I do know that it changed between
1.6.7 and 1.7.x, so you get:

candle:~$ ruby/ruby -v
ruby 1.7.2 (2002-05-11) [i686-linux]
candle:~$ ruby/ruby -e ‘p (0…4).type’
Range

You can always use parens to make sure:

p ((0…4).type)

David

···

On Mon, 5 Aug 2002, Wejn wrote:

–
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web: http://pirate.shu.edu/~blackdav