On Fri, 27 Apr 2012 14:29:40 -0400, Joseph Rushton Wakeling
<[email protected]> wrote:
On 27/04/12 20:25, H. S. Teoh wrote:
On Fri, Apr 27, 2012 at 07:25:30PM +0200, Joseph Rushton Wakeling wrote:
I was more concerned that the compiler wasn't identifying what to me
was a violation of purity. I'm fairly sure I can also find a way to
make some of those "nothrow" functions throw an error ...
It's not a violation of purity, it's just "weak purity". If you try to
access a global variable, for example, it will trigger an error.
Thanks for the extended description of weak purity -- it's been very
helpful in understanding the concept better.
Is there a particular way in which I can explicitly mark a function as
strongly pure?
No, just make sure all the parameters and the result are either immutable
or implicitly castable to immutable (hard to explain this better).
Hm... gives me a thought that unit tests should have a helper that allows
ensuring this:
static assert(isStrongPure!fn);
Or maybe __traits(isStrongPure, fn) if it's too difficult to do in a
library.
... yes, as I just found out when I decided to test it 2 minutes ago
:-) OTOH I found that with or without the nothrow option, when the
-release flag was used in compiling the code, the error was not thrown
and the program did not exit -- it just sat there seemingly running but
doing nothing. This was unexpected ...
The deliberate error was in this case a range exception when accessing
an array.
array bounds checks and asserts are turned off during -release compilation
:)
-Steve
