[gecode-users] int vs. unsigned int for Matrix dimensions

[Christian Schulte]

Hi Gregory,

You are touching a slightly weird aspect of Gecode... The choice of int as
opposed to unsigned int for the Matrix class is actually deliberate. This
choice is not only done for Matrix but for many other datastructures that
are defined by Gecode (for example, VarArray, ViewArray, etc). I know that
the choice of unsigned int sounds more appealing but we have made the
opposite decision and try to be as consistent with the choice of int rather
than unsigned int.

There are two reasons. The first is simple and maybe is not even very
convincing. The average loop written to iterate over arrays etc is typically
an int and not an unsigned int. To avoid compiler warnings, Gecode follows
in this. Then, the second reason (possibly not more convincing than the
first one) is that integer variables take int values and very often array
access is wrt a value included in the domain of an integer variable. Here we
go.

We tried to use unsigned int but it was in fact just too painful (lots of
explicit casts in order to avoid warnings). Changing int to unsigned int and
be consistent about that change would be a massive effort with little gain.

I know. Sad but true.

Cheers
Christian

--
Christian Schulte, web.ict.kth.se/~cschulte/


-----Original Message-----
From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf
Of Gregory Crosswhite
Sent: Friday, January 14, 2011 6:26 PM
To: users at gecode.org
Subject: [gecode-users] int vs. unsigned int for Matrix dimensions

Hey everyone,

Is there a reason why the Matrix class uses "int" for the type of its 
dimensions instead of "unsigned int"?  If there isn't a reason not to 
use "unsigned int" for the type of the dimensions, then may I submit a 
patch or something to change it to use "unsigned int"?

Thanks!
Greg

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