Ok, for basic types I know I can use

int[char[]] assoc;
assoc["3"] = 3;

And for classes I can do.

Class[char[]] assoc;
assoc["3"] = new Class;

Now, lets say I want to test if assoc["3"] has already been initialized before I allocate it, but testing it with

if (assoc["3"] is null)
   assoc["3"] = new Class;

I get a seg fault. Any other way to do this? File attached to better illustrate my problem. Thanks.

~ Clay

On Wed, 26 Apr 2006 23:49:07 -0500, clayasaurus wrote:

> import std.stdio;
> 
> int main()
> {
> 	char[] i = "3";
> 
> 	int[char[]] assoc;
> 	assoc[i] = 3;
> 
> 	Class[char[]] assoc2;
> 
> 	// doesn't work
> 	if (assoc2[i] is null)
> 		assoc2[i] = new Class;
> 
> 	// works
> 	assoc2[i] = new Class;
> 
> 	writefln("hi");
> 
> 	return 0;
> }
> 
> class Class
> {
>   public:
> 	this(){}
> 	int x,y;
> }

Try this ...

  if (!(i in assoc2))
    assoc2[i] = new Class;

-- 
Derek
(skype: derek.j.parnell)
Melbourne, Australia
"Down with mediocracy!"
27/04/2006 3:09:47 PM

Derek Parnell wrote:
> On Wed, 26 Apr 2006 23:49:07 -0500, clayasaurus wrote:
> 
> Try this ...
> 
>   if (!(i in assoc2))
>     assoc2[i] = new Class;
> 

Thanks :) That seems to do the trick.

clayasaurus wrote:
<snip>
> Class[char[]] assoc;
> assoc["3"] = new Class;
> 
> Now, lets say I want to test if assoc["3"] has already been initialized before I allocate it, but testing it with
> 
> if (assoc["3"] is null)
>   assoc["3"] = new Class;
> 
> I get a seg fault.
<snip>

That's strange.  It should be an ArrayBoundsError.

Stewart.

You should use '(("3" in assoc) == null)' instead of '(assoc["3"] is null)'

Regards,
Alberto Simon
"Stewart Gordon" <smjg_1998@yahoo.com> escribió en el mensaje
news:e2qh6d$1lfk$2@digitaldaemon.com...
> clayasaurus wrote:
> <snip>
>> Class[char[]] assoc;
>> assoc["3"] = new Class;
>>
>> Now, lets say I want to test if assoc["3"] has already been initialized before I allocate it, but testing it with
>>
>> if (assoc["3"] is null)
>>   assoc["3"] = new Class;
>>
>> I get a seg fault.
> <snip>
>
> That's strange.  It should be an ArrayBoundsError.
>
> Stewart.

The correct use of AAs is so intuitive I'm amazed anyone ever gets it wrong.  It's times like this when I wish I'd been more vocal about actually liking the old syntax :-p


Alberto Simon wrote:
> You should use '(("3" in assoc) == null)' instead of '(assoc["3"] is null)'
> 
> Regards,
> Alberto Simon
> "Stewart Gordon" <smjg_1998@yahoo.com> escribió en el mensaje news:e2qh6d$1lfk$2@digitaldaemon.com...
>> clayasaurus wrote:
>> <snip>
>>> Class[char[]] assoc;
>>> assoc["3"] = new Class;
>>>
>>> Now, lets say I want to test if assoc["3"] has already been initialized before I allocate it, but testing it with
>>>
>>> if (assoc["3"] is null)
>>>   assoc["3"] = new Class;
>>>
>>> I get a seg fault.
>> <snip>
>>
>> That's strange.  It should be an ArrayBoundsError.
>>
>> Stewart. 
> 
> 

Sean Kelly wrote:
> The correct use of AAs is so intuitive I'm amazed anyone ever gets it wrong.  It's times like this when I wish I'd been more vocal about actually liking the old syntax :-p
<snip top of upside-down reply>

What old syntax?

The in operator has always been the correct way to check whether an AA contains a given key.  Looking it up and comparing it against valuetype.init was never a general solution.  And

    if ("3" in assoc)

or

    if (!("3" in assoc))

still works just the same.

[F'up back to d.D.learn]

Stewart.