you can just create some basic script to do this whenever you need this. The script would be slower than if it was implimented internally, but I have to agree with madewokherd that it would definately hinder over all performance and all for a very specific circumstance.

Here's an example script for you:

Code:
alias wee { 
  echo -a And here we go..  (10 is the limit as set in the alias sdi, and 1 is the default number)
  set2 wee 1
  echo -a Set it as: %wee
  inc2 wee 6
  echo -a Added 6: %wee
  dec2 wee 3
  echo -a Subtracted 3: %wee
  inc2 wee 50
  echo -a Incremented it 40 past it's limit: %wee
  unset %wee
  echo All done!
}
alias set2 {
  set % $+ [ $1- ]
  sdi $1
  }
alias inc2 { 
 inc % $+ [ $1- ]
  sdi $1
}
alias dec2 { 
 dec % $+ [ $1- ]
  sdi $1
}
alias -l sdi { if ( [ % $+ [ $1 ] ] >= 10) {  set  % $+ [ $1 ] 1 } }


If you have the number decreasing every second or incrementing every second or something, then I suggest to you to create a more complex script that will have a timer running evert second, which will run an alias which will look through a list of variable names which would be stored in a hash file to check all the variables every second, removing variables that stop decreasing or incrementing, untill the hash file is empty, then the timer would be unset.

I think Narusegawa_Naru's suggestion is a much better suggestion, but still not a very important one.

- Wherever you go there you are.[color:lightgreen]