With (MPI)

with

{with:var,val,expr..}

This defines a new variable with the given name, and sets it's value to the given val.

Up to 7 expr's are allowed, but the only value returned to {with}'s caller, is the value returned by the evaluation of the last expr. If there is already a variable of the same name, then this command will override that variable, for the duration of the {with:} command.

The new variable is only valid to use within the confines of the {with:} command, and it will go away after the command completes.

This provides scoped variables quite effectively. NOTE: There can be no more than 32 variables defined at any one time, total. This includes variables that are defined within macros, or properties or lists that are executed with {exec:} or {lexec:}.

Here's an example to illustrate the scope of variables inside of {with:} commands:

     {prop:_mydesc}                           «- {&people} not defined.
     {with:people,{contents:here,players},    «- Defining.  Not available yet.
         {if:{count:{&people}},               «- It's usable now.
             The players awake here are
             {lit: }                          «- just puts in a space.
             {commas:{&people},{lit: and },
                 who,{name:{&who}}            «- uses {&who} as temp var.
             }                                «- {&who} no longer defined.
         }
     }                                        «- {&people} no longer defined.