Associative arrays give compile error

[Bob Cowdery]

 On 05/10/2010 13:05, Denis Koroskin wrote:
> On Tue, 05 Oct 2010 15:53:55 +0400, Denis Koroskin <2korden at gmail.com>
> wrote:
>
>> On Tue, 05 Oct 2010 15:40:39 +0400, Bob Cowdery
>> <bob at bobcowdery.plus.com> wrote:
>>
>>>  On 05/10/2010 12:13, Denis Koroskin wrote:
>>>> On Tue, 05 Oct 2010 15:08:39 +0400, Bob Cowdery
>>>> <bob at bobcowdery.plus.com> wrote:
>>>>
>>>>>  On 05/10/2010 12:04, Denis Koroskin wrote:
>>>>>> On Tue, 05 Oct 2010 14:57:22 +0400, Bob Cowdery
>>>>>> <bob at bobcowdery.plus.com> wrote:
>>>>>>
>>>>>>>  On 05/10/2010 11:45, Denis Koroskin wrote:
>>>>>>>> On Tue, 05 Oct 2010 14:23:47 +0400, Bob Cowdery
>>>>>>>> <bob at bobcowdery.plus.com> wrote:
>>>>>>>>
>>>>>>>>>  I can't seem to get any sense out of associative arrays. Even
>>>>>>>>> the
>>>>>>>>> simplest definition won't compile so I must be doing something
>>>>>>>>> daft.
>>>>>>>>>
>>>>>>>>> int[string] aa = ["hello":42];
>>>>>>>>>
>>>>>>>>> Error: non-constant expression ["hello":42]
>>>>>>>>>
>>>>>>>>> What exactly is not constant about this. The example is straight
>>>>>>>>> out the
>>>>>>>>> book. Using D 2.0.
>>>>>>>>>
>>>>>>>>> bob
>>>>>>>>
>>>>>>>> What exactly compiler version are you using (run dmd with no
>>>>>>>> args)?
>>>>>>>> Works perfectly fine here (dmd2.049).
>>>>>>>
>>>>>>> It says 2.049. How odd. I've got a fair amount of code and
>>>>>>> everything
>>>>>>> else compiles fine.
>>>>>>
>>>>>> Can you please post complete code snippet that fails to compile?
>>>>>>
>>>>>> Here is the code I used to test:
>>>>>>
>>>>>> module aa;
>>>>>>
>>>>>> import std.stdio;
>>>>>>
>>>>>> void main()
>>>>>> {
>>>>>>     int[string] aa = ["hello":42];
>>>>>>     writeln(aa["hello"]);
>>>>>> }
>>>>>>
>>>>>> # dmd -run aa.d
>>>>>
>>>>> Ah! It's some other code below it that is not giving an error but
>>>>> causing the error above. So the compiler is getting confused. What
>>>>> I was
>>>>> actually trying to do was create an associative array with a
>>>>> string as a
>>>>> key and a Tuple as the value. Now
>>>>>
>>>>> auto aa = [
>>>>>     "some string": (100.0, 6100.0)
>>>>> ]
>>>>>
>>>>> compiles but is clearly wrong and gives rise to other errors.  Does
>>>>> anyone know the correct way to define this and then access the tuple.
>>>>
>>>> import std.stdio;
>>>> import std.typecons;
>>>>
>>>> void main()
>>>> {
>>>>     auto aa = ["hello": tuple(100.0, 6100.0)];
>>>>     auto result = aa["hello"];
>>>>
>>>>     writeln(result.field[0], " ", result._1); // primary and
>>>> alternative way
>>>> }
>>>
>>> Thanks. I've established that works for me and also that the actual
>>> array I'm using also works in the test program but it won't compile in
>>> the real program. I've commented everything else out of the file and
>>> just left...
>>>
>>> import std.typecons;
>>>
>>> auto A_RX_FILT = [
>>>     "6K0": tuple(100.0, 6100.0),
>>>     "2K4": tuple(300.0, 2700.0),
>>>     "2K1": tuple(300.0, 2400.0),
>>>     "1K0": tuple(300.0, 1300.0),
>>>     "500": tuple(500.0, 1000.0),
>>>     "250": tuple(600.0, 850.0),
>>>     "100": tuple(700.0, 800.0)
>>> ];
>>>
>>
>> You are trying to declare global variable and initialize at in
>> compile time. As far as I know, you can't initialize AA at compile
>> time atm (this might be implemented in future though).
>>
>> As such, I'd recommend against using global variables (try moving it
>> to some class or something). Anyway, you need to initialize it at
>> some point, either manually:
>>
>> Tuple!(double,double)[string] A_RX_FILT;
>>
>> void init()
>> {
>>      A_RX_FILT = [
>>     "6K0": tuple(100.0, 6100.0),
>>     "2K4": tuple(300.0, 2700.0),
>>     "2K1": tuple(300.0, 2400.0),
>>     "1K0": tuple(300.0, 1300.0),
>>     "500": tuple(500.0, 1000.0),
>>     "250": tuple(600.0, 850.0),
>>     "100": tuple(700.0, 800.0)
>>      ];
>> }
>>
>> or automatically at thread startup:
>>
>> static this()
>> {
>>      init();
>> }
>>
>> Hope that helps.
>
> See my other reply for a better solution.

Thanks very much. It compiles now. The reason I thought it was an issue
was because sometime it did compile a global associative array. I need
to do some homework on what 'this' does. It's clearly a powerful concept
and has wider application than class constructors.