[R] Unnecesary code?

Hun S. Tesatte hunsyntesat at hush.com
Thu Nov 19 10:23:18 CET 2009



On Thu, 19 Nov 2009 00:13:27 +0100 Duncan Murdoch 
<murdoch at stats.uwo.ca> wrote:
>hunsyntesat at 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 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.  

There is also a negligible loss in performance when the inessential 
stack variable is allocated.

-- Hun



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