Associative arrays give compile error
Lars T. Kyllingstad
public at kyllingen.NOSPAMnet
Tue Oct 5 05:03:21 PDT 2010
On Tue, 05 Oct 2010 12:50:44 +0100, Bob Cowdery wrote:
> On 05/10/2010 12:40, Bob Cowdery 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)
>> ];
>>
>> I get an error on every line:
>> Definitions\dspDefs.d|51|Error: cannot evaluate tuple(100,6100) at
>> compile time|
>> Definitions\dspDefs.d|51|Error: cannot evaluate tuple(300,2700) at
>> compile time|
>> Definitions\dspDefs.d|51|Error: cannot evaluate tuple(300,2400) at
>> compile time|
>> Definitions\dspDefs.d|51|Error: cannot evaluate tuple(300,1300) at
>> compile time|
>> Definitions\dspDefs.d|51|Error: cannot evaluate tuple(500,1000) at
>> compile time|
>> Definitions\dspDefs.d|51|Error: cannot evaluate tuple(600,850) at
>> compile time|
>> Definitions\dspDefs.d|51|Error: cannot evaluate tuple(700,800) at
>> compile time|
>> Definitions\dspDefs.d|51|Error: cannot evaluate tuple(100,6100) at
>> compile time|
>> Definitions\dspDefs.d|51|Error: cannot evaluate tuple(300,2700) at
>> compile time|
>> Definitions\dspDefs.d|51|Error: cannot evaluate tuple(300,2400) at
>> compile time|
>> Definitions\dspDefs.d|51|Error: cannot evaluate tuple(300,1300) at
>> compile time|
>> Definitions\dspDefs.d|51|Error: cannot evaluate tuple(500,1000) at
>> compile time|
>> Definitions\dspDefs.d|51|Error: cannot evaluate tuple(600,850) at
>> compile time|
>> Definitions\dspDefs.d|51|Error: cannot evaluate tuple(700,800) at
>> compile time|
>> ||=== Build finished: 14 errors, 0 warnings ===|
>>
>> This is a bit worrying now. I moved the array into the file that uses
>> it but I still get the same errors. Any ideas?
>>
>>
> Oh dear, this is getting worse and worse. I've still got problems with a
> simple definition. If I take out the one with the tuple and leave in
> this one:
>
> enum E_MODE
> {
> LSB, // 0
> USB, // 1
> DSB, // 2
> CWL, // 3
> CWU, // 4
> FMN, // 5
> AM, // 6
> DIGU, // 7
> SPEC, // 8
> DIGL, // 9
> SAM, // 10
> DRM // 11
> }
> // Associative array for translation
> auto A_MODE = [
> "LSB": E_MODE.LSB,
> "USB": E_MODE.USB,
> "DSB": E_MODE.DSB,
> "CWL": E_MODE.CWL,
> "CWU": E_MODE.CWU,
> "FMN": E_MODE.FMN,
> "AM": E_MODE.AM,
> "DIGU": E_MODE.DIGU,
> "SPEC": E_MODE.SPEC,
> "DIGL": E_MODE.DIGL,
> "SAM": E_MODE.SAM,
> "DRM": E_MODE.DRM
> ];
>
> I get:
> Definitions\dspDefs.d|25|Error: non-constant expression
> ["LSB":cast(E_MODE)0,"USB":cast(E_MODE)1,"DSB":cast(E_MODE)2,"CWL":cast
(E_MODE)3,"CWU":cast(E_MODE)4,"FMN":cast(E_MODE)5,"AM":cast(E_MODE)
6,"DIGU":cast(E_MODE)7,"SPEC":cast(E_MODE)8,"DIGL":cast(E_MODE)
9,"SAM":cast(E_MODE)10,"DRM":cast(E_MODE)11]|
> ||=== Build finished: 1 errors, 0 warnings ===|
>
> Something is seriously broken here.
No, nothing is broken. :)
The problem is that you are trying to create an associative array at
compile time, which isn't possible. This works:
void main()
{
auto foo = [ "Hello" : "World" ]; // Array created at run time
writeln(foo);
}
This doesn't work:
auto foo = [ "Hello" : "World" ]; // Cannot create AA at compile time
void main()
{
writeln(foo);
}
To create a module-level AA which is initialised on program start, use a
module constructor:
string[string] foo;
static this()
{
foo = [ "Hello" : "World" ];
}
void main()
{
writeln(foo);
}
In your case, this would mean:
Tuple!(double, double)[string] A_RX_FILT;
static this()
{
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)
];
}
-Lars
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