[aplusdev] using mapped variable in as a function argument?

[John.Mizel at MorganStanley.com]

Sasha.

A+ variables are referneced counted.  A "regular" variable (not one 
attached to a mapped file) won't be copied unless the function foo 
modifies it.

Variables attached to files read/write behave differently.  A useful debug 
command is "$dbg +beam".  This will show when variables are attached and 
silently detached from a .m file.

So

  a := iota 100

foo{x}: {
   x := +/x;
   b :=max x;
   x[0] := 100         lamp a copy of x is made
  a,b
}

  a := 1 beam "file.m"

foo{x}: {
   x := +/x;
   b :=max x;
   x[0] := 100         lamp a is ACTUALLY modified NO copy made
   a,b
}

Thanks,
John

A+ variables are referenced counted so for a variable that isn't passed to 
foo 

On Mon, 11 Feb 2002, Alexander Skomorokhov wrote:

> One more question on memory mapped files.
> Sorry if the answer is somewhere in the manual.
> 
> $mode ascii
> z:=1 beam 'file.m'
> 
> foo x:{
> a:=+/x;
> b:=max x;
> a,b}
> 
> When I call function as
> 
> foo t
> 
> Is local copy of t created as x in workspace?
> 
> Thanks,
> Sasha.
> 
> 

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