On 4/16/2011 11:52 AM, bearophile wrote:
Walter:
Saying it is a safe way to break purity assumes that there was no purpose
to the purity. There is no guaranteed safe way to break purity, with or
without a compiler switch.
The compiler switch I am talking about doesn't break purity. Its purpose is
similar to removing the "pure" attributes from the source code. And doing it
is usually safe, if you do it in the whole program.
No, it is not. You seem to be thinking that purity is just a bug finding or
optimization feature. That is not so. Purity is a guarantee that can be relied
upon for a program's behavior. Breaking purity breaks that guarantee.
(Think multithreaded programs, for example.)
If you take a D2 program, you remove all its pure attributes and you compile
it again, the result is generally a program just as correct as before.
"generally" is not a verifiable characteristic. When we talk about safety, we're
talking about a verifiable guarantee.
