# RCR: Comparing multiple values **URL:** \ **Category:** ruby-talk\ **Created:** [25 April 2004 16:09 UTC](https://rubytalk.org/t/rcr-comparing-multiple-values/11216 "2004-04-25T16:09:05Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Kristof\_Bastiaensen1](https://avatars.discourse-cdn.com/v4/letter/k/9fc29f/32.png) [@Kristof\_Bastiaensen1](https://rubytalk.org/u/Kristof_Bastiaensen1)\ **Post date:** [25 April 2004 16:09 UTC](https://rubytalk.org/t/rcr-comparing-multiple-values/11216/1 "2004-04-25T16:09:05Z")
Hi list, wouldn’t it be nice to be able to compare multiple values? for example: x, y == 1, 2 #equivalent to x == 1 && y == 2 right now you can do [x, y] == [1, 2] but IMHO it doesn’t look so nice Kristof ---
**Author:** ![Szymon\_Drejewicz1](https://avatars.discourse-cdn.com/v4/letter/s/f07891/32.png) [@Szymon\_Drejewicz1](https://rubytalk.org/u/Szymon_Drejewicz1)\ **Post date:** [26 April 2004 06:44 UTC](https://rubytalk.org/t/rcr-comparing-multiple-values/11216/2 "2004-04-26T06:44:04Z")
Kristof Bastiaensen wrote: > wouldn’t it be nice to be able to compare multiple values? > for example: > x, y == 1, 2 > #equivalent to x == 1 && y == 2 For me that notation has one drawback: what should happend if y = 5 and you’ll write [x, y == 1, 2] ? Is it an array with three elements [x, false, 2] ? or an array with one element which has value of “multiple comaprision” [false] ? > **···** > > – > Szymon Drejewicz ---
**Author:** ![Joel\_VanderWerf1](https://avatars.discourse-cdn.com/v4/letter/j/94ad74/32.png) [@Joel\_VanderWerf1](https://rubytalk.org/u/Joel_VanderWerf1)\ **Post date:** [26 April 2004 06:58 UTC](https://rubytalk.org/t/rcr-comparing-multiple-values/11216/3 "2004-04-26T06:58:31Z")
Szymon Drejewicz wrote: > Kristof Bastiaensen wrote: > > > wouldn’t it be nice to be able to compare multiple values? > > for example: > > x, y == 1, 2 > > #equivalent to x == 1 && y == 2 > > For me that notation has one drawback: what should happend if > y = 5 > and you’ll write > [x, y == 1, 2] > ? > > Is it an array with three elements > [x, false, 2] > ? > > or an array with one element which has value of “multiple comaprision” > [false] > ? Not sure that this shows anything, but the current behavior for = instead of == is: [x, y = 1, 2] =\> [0, 1, 2] So it looks like the array context overrides the parallel assignment? It’s not a good analogy, though, because == is a method and = is not. ---
**Author:** ![Laurent\_Julliard4](https://avatars.discourse-cdn.com/v4/letter/l/ebca7d/32.png) [@Laurent\_Julliard4](https://rubytalk.org/u/Laurent_Julliard4)\ **Post date:** [26 April 2004 08:29 UTC](https://rubytalk.org/t/rcr-comparing-multiple-values/11216/4 "2004-04-26T08:29:04Z")
It should be just ‘false’, as expressed in the first message (i.e. x==1 and 5==2) I mean, if we consider ‘,’ as an expression that creates a list object, than 1,2 == could be just some kind of sugar. But chosing some kind of precedence would probably be impossible, or wqould break many of the actual behaviours. > **···** > > il Mon, 26 Apr 2004 08:39:26 +0200, Szymon Drejewicz [drejewic@wsisiz.edu.pl](mailto:drejewic@wsisiz.edu.pl) ha scritto:: > > > Kristof Bastiaensen wrote: > > > > > wouldn’t it be nice to be able to compare multiple values? > > > for example: > > > x, y == 1, 2 > > > #equivalent to x == 1 && y == 2 > > > > For me that notation has one drawback: what should happend if > > y = 5 > > and you’ll write > > [x, y == 1, 2] > > ? > > > > Is it an array with three elements > > [x, false, 2] > > ? > > > > or an array with one element which has value of “multiple comaprision” > > [false] > > ? ---
**Author:** ![Kristof\_Bastiaensen1](https://avatars.discourse-cdn.com/v4/letter/k/9fc29f/32.png) [@Kristof\_Bastiaensen1](https://rubytalk.org/u/Kristof_Bastiaensen1)\ **Post date:** [26 April 2004 09:34 UTC](https://rubytalk.org/t/rcr-comparing-multiple-values/11216/5 "2004-04-26T09:34:17Z")
> > For me that notation has one drawback: what should happend if > > y = 5 > > and you’ll write > > [x, y == 1, 2] > > ? > > > > Is it an array with three elements > > [x, false, 2] > > ? > > > > or an array with one element which has value of “multiple comaprision” > > [false] > > ? That would be a problem indeed. Note that the same aplies to method calling: foo(a, b == 1, 2) The expansion of (x, y == 1, 2) should then occur only outside parameter lists. > It should be just ‘false’, as expressed in the first message (i.e. > x==1 and 5==2) It surely shouldn’t be false, because that would disable comparisons inside parameter lists. > I mean, if we consider ‘,’ as an expression that creates a list > object, than 1,2 == could be just some kind of sugar. > But chosing some kind of precedence would probably be impossible, or > wqould break many of the actual behaviours. I wouldn’t consider ‘,’ as an expression that creates any object, but rather as a way to pass multiple arguments to methods and continuations. This is close to the way it actually is in Ruby. This would be a syntax extension. However (x, y == exp1, exp2) would be different from (x == exp1 && y == exp2) because it would evaluate the parameters first, and then compare the results. Another construct that might be useful: x, y += 1, 2 #(meaning x += 1; y += 2) ---
**Author:** ![Kristof\_Bastiaensen1](https://avatars.discourse-cdn.com/v4/letter/k/9fc29f/32.png) [@Kristof\_Bastiaensen1](https://rubytalk.org/u/Kristof_Bastiaensen1)\ **Post date:** [26 April 2004 09:49 UTC](https://rubytalk.org/t/rcr-comparing-multiple-values/11216/6 "2004-04-26T09:49:04Z")
I think the analogy is good enough. Ruby already does some method reordering on Arithmetic Operators, so why not on this one? > **···** > > On Mon, 26 Apr 2004 15:58:31 +0900, Joel VanderWerf wrote: > > > Not sure that this shows anything, but the current behavior for = > > instead of == is: > > > > [x, y = 1, 2] > > =\> [0, 1, 2] > > > > So it looks like the array context overrides the parallel assignment? > > > It’s not a good analogy, though, because == is a method and = is not.