🚀 go-pugleaf

In article <1arv24INN3nl@swan.doc.ic.ac.uk>, iwm@doc.ic.ac.uk (Ian W Moor) writes:
|> |> Example:
|> |> 
|> |>     PROCEDURE PrintString(s : ARRAY OF CHAR); (* $CopyArrays- *)
|> |>     
|> |> Another solution would be to make to Compiler intelligent enough to see that
|> |> the ARRAY ist not changed in the procedure and then chose this option 
|> |> automatically.
|> |> 
|> 
|> Getting the compiler to do it right is much the best way ! What happens if
|> you disable array copying and then later by mistake you modify the procedure 
|> to change the string ?

We extended our compiler with a 3rd procedure parameter type, REF.  REF
parameters are pass-by-reference just like VAR except that the value
can't be modified.  For expressions and constants whose address can't be
taken a temporary variable is created and its address is passed.

This makes a tremendous difference in performance for some code and
especially for open arrays.

I have seen similar things in Pascal compilers (often called CONST or
somesuch).
-- 

- Bill Seurer     Language and Compiler Development      IBM Rochester, MN
  Internet: BillSeurer@vnet.ibm.com    America On-Line: BillSeurer@aol.com