Assigning to a list within a loop (PR#175)

[wvenable@arcola.stats.adelaide.edu.au]

We noticed this bug in more complex code, but this succinctly
describes the phenomenon.

If you do not re-initialize a each time in the following loop,
the final value only is assigned to all places when the loop is
complete.

> a <- b <- list()
> for(i in 1:5) {
+	a$alpha <- i
+	b[[i]] <- a
+	}
> unlist(b)
alpha alpha alpha alpha alpha 
    5     5     5     5     5 

If a is re-created each time, however the correct behaviour
happens:


> b <- list()
> for(i in 1:5) {
+	  a <- list(alpha = i)
+	  b[[i]] <- a
+	  }
> unlist(b)
alpha alpha alpha alpha alpha 
    1     2     3     4     5 

> version
           _                 
platform   i586-unknown-linux
arch       i586              
os         linux             
system     i586, linux       
status                       
status.rev 0                 
major      0                 
minor      64.0              
year       1999              
month      April             
day        8                 
language   R                 
>

Bill Venables & Berwin Turlach.

-- 
-----------------------------------------------------------------
Bill Venables, Statistician, CMIS Environmetrics Project.

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Telephone: +61 7 3826 7251     Email: Bill.Venables@cmis.csiro.au     
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