: From: Larry Wall la...@wall.org
: > Of course, there are issues here if the code modifies those
: > variables, since the issue of whether a variable is rw is
: > really distinct from whether it represents a pass by value
: > or reference.  Slapping a "constant" on it is a bald-faced
: > attempt to get the speed of pass-by-reference with the
: > guarantees of pass-by-value.  Perhaps there should be a way
: > to declare a parameter to be pass-by-value, producing a
: > modifiable variable that does not affect the caller's value.
: > But I'm not sure saving one assignment in the body is worth
: > the extra mental baggage.
:
: I'm not sure I read that right, but it sounds like you're implying that
: pass-by-values will be read-only.  Is that the plan?

The default is pass-by-reference, but non-modifiable.  If there's a
pass-by-value, it'll have to be specially requested somehow.

This is a minimal difference from Perl 5, in which everything was
pass-by-reference, but modifiable.   To get pass-by-value, you just
do an assignment.  :-)

Larry