digitalmars.D - allocate hash table manually
- Mildred <mildred593 online.fr> Sep 05 2006
- Johan Granberg <lijat.meREM OVEgmail.com> Sep 05 2006
- Mildred <mildred593 online.fr> Sep 06 2006
Hi,
I'm a new user od D language but immediately, I felt that was the
language I always looking for. So I'm very happy to use it.
I'm trying to convert my recent project to C (using a garbage collector
as library) to D. It's a script language with a lisp syntax.
My question is how do I use new to allocate a hash table. My code is as
follows :
class Value {
...
protected Value[char[]] _environment = null;
...
public void env_make(Stack S){
_environment = new Value[char[]];
}
...
}
But the compiler says : need size of rightmost array, not type char[]
My problem is that I want some Value objects to have an environment,
and I want others objects without environment (so I use null).
How can I do that ?
Thanks
Mildred
--
Mildred <xmpp:mildred jabber.fr> <http://mildred632.free.fr/>
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Sep 05 2006
Mildred wrote:Hi, I'm a new user od D language but immediately, I felt that was the language I always looking for. So I'm very happy to use it. I'm trying to convert my recent project to C (using a garbage collector as library) to D. It's a script language with a lisp syntax. My question is how do I use new to allocate a hash table. My code is as follows : class Value { ... protected Value[char[]] _environment = null; ... public void env_make(Stack S){ _environment = new Value[char[]]; } ... } But the compiler says : need size of rightmost array, not type char[] My problem is that I want some Value objects to have an environment, and I want others objects without environment (so I use null). How can I do that ? Thanks Mildred
I think this is what I have used. class Value { ... protected Value[char[]] _environment = null; ... public void env_make(Stack S){ Value[char[]] e; _environment = e; } ... }
Sep 05 2006
Mildred wrote:Le mar 05/09/2006 __ 20:01 Johan Granberg __ __crit:I think this is what I have used. class Value { ... protected Value[char[]] _environment = null; ... public void env_make(Stack S){ Value[char[]] e; _environment = e; } ... }
Thanks, that helps me. Isn't there a solution with the new keyword, it is the normal way to allocate on the heap, no ?
An empty hash is already "null" by default. Basically you're doing something stupid here - see this example: template Hash(K,V) { V[K] Hash() { V[K] tmp; return tmp; } } void main() { int[int] a; assert(a is null); a[1] = 1; assert(a !is null); a = Hash!(int, int); assert(a is null); a[1] = 1; assert(a !is null); a = Hash!(int, int); assert(a is null); } The compiler indicates a hash is empty by returning a null. Here Hash! creates an empty hash and returns it - hash array literals can be implemented in the same fashion.
Sep 06 2006
=?ISO-8859-1?Q?Jari-Matti_M=E4kel=E4?= <jmjmak utu.fi.invalid> Jari-Matti Mäkelä wrote:An empty hash is already "null" by default. Basically you're doing something stupid here
Sorry, I was a bit rude. I always rely on the implicit initialization a bit too much. I hope the Hash-template will give the functionality you were looking for.
Sep 06 2006
Jari-Matti Mäkelä wrote:main() { int[int] a; assert(a is null); a[1] = 1; assert(a !is null); a = Hash!(int, int); assert(a is null); a[1] = 1; assert(a !is null); a = Hash!(int, int); assert(a is null); }
Dammit, here's an optimized version (stupid me):void main() { int[int] a; assert(a is null); a[1] = 1; assert(a !is null); a = null; // "creates" a new hash assert(a is null); a[1] = 1; assert(a !is null); a = null; // "creates" yet another new hash assert(a is null); }
Sep 06 2006
Le mar 05/09/2006 __ 20:01 Johan Granberg __ __crit:I think this is what I have used. class Value { ... protected Value[char[]] _environment = null; ... public void env_make(Stack S){ Value[char[]] e; _environment = e; } ... }
Thanks, that helps me. Isn't there a solution with the new keyword, it is the normal way to allocate on the heap, no ? -- Mildred <xmpp:mildred jabber.fr> <http://mildred632.free.fr/> Clef GPG : <hkp://pgp.mit.edu> ou <http://mildred632.free.fr/gpg_key> Fingerprint : 197C A7E6 645B 4299 6D37 684B 6F9D A8D6 [9A7D 2E2B]
Sep 06 2006