Optimizing Immutable and Purity

Walter Bright newshound1 at digitalmars.com
Tue Dec 23 12:23:09 PST 2008


Andrei Alexandrescu wrote:
> Bill Baxter wrote:
>> On Tue, Dec 23, 2008 at 11:30 AM, Jerry Quinn <jlquinn at optonline.net> 
>> wrote:
>>> This was an interesting read.  It would be nice to see a discussion 
>>> of how const is going to fit in in terms of optimization potential, 
>>> since you can always cast it away.
>>
>> It's basically useless for optimizations I think.
>> Even if the view of the data you have is const, someone else might
>> have a non-const view of the same data.
>> So for instance, if you call any function, your "const" data could
>> have been changed via non-const global pointers to the same data.
>>
>> --bb
> 
> Const is still useful because inside a function you know for sure that 
> another thread can't modify the data.

I think you meant immutable.



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