On 19/11/2009 4:23 AM, Hun S. Tesatte wrote:
On Thu, 19 Nov 2009 00:13:27 +0100 Duncan Murdoch
<murd...@stats.uwo.ca> wrote:
hunsynte...@hush.com wrote:
Dear R-ers,
While browsing the R sources, I found the following piece of
code
in src\main\memory.c:
static void reset_pp_stack(void *data)
{
R_size_t *poldpps = data;
R_PPStackSize = *poldpps;
}
To me, it looks like the poldpps pointer is a nuissance; can't
you
just cast the data pointer and derefer it at once? Say,
static void reset_pp_stack(void *data)
{
R_PPStackSize = * (R_size_t *) data;
}
What would you gain by this change?
Duncan Murdoch
Seriously? What would you gain by rejecting the change?
I would save about an hour spent making the change, testing and
committing it.
I think the gain is obvious, even if not essential: the code is
cleaner. If there is a choice between two different pieces of code
that have the same effect, choosing the simpler makes it easier to
maintain the code, and easier for a casual user to understand
what's going on. Anyone looking at the original code for the first
time will have to realise that poldpps is a nuissance variable with
no practical importance and no gain whatsoever, the change cuts
this need.
But it makes the expression more complex, and doesn't give a hint about
what's going on. The name poldpps adds a bit of explanation of what the
assumption is about what's being passed in data.
There is also a negligible loss in performance when the inessential
stack variable is allocated.
There is likely no variable allocated. Compilers are reasonably smart
these days.
Duncan Murdoch
-- Hun
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