On 04/08/2011 03:13 PM, Steven Schveighoffer wrote:
On Fri, 08 Apr 2011 06:44:42 -0400, Simen kjaeraas <[email protected]>
wrote:
On Fri, 08 Apr 2011 12:46:08 +0200, Morlan <[email protected]> wrote:
It is OK if I write
int[char[]] asr;
asr["hello"] = 10;
but the following does not compile:
char[] car = "hello";
What is the explanation for this behaviour?
The first should not be allowed. It is a mistake to use non-immutable
keys for an associative array.
int[char[]] asr;
pragma(msg, typeof(asr).stringof);
outputs:
AssociativeArray!(const(char)[],int)
So the compiler adds const to the keys, which is why it works.
Do I think this is the correct behavior? Absolutely not. First, it prevents
nothing as far as modifying keys (const accepts mutable keys as well as const
and mutable ones). Second, I believe you should be able to use whatever key
constancy you want. We should just say if you do the wrong thing, it's
undefined. Maybe @safe code can only use immutable keys. Third, if it must be
illegal to have an AA with mutable keys, it should be an error, not silently
change to const.
I agree on points 1 & 3. "Second" looks dangerous to me.
Denis
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