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digitalmars.D.learn - Why doesn't this have a length?

reply Magnus Lie Hetland <magnus hetland.org> writes:
In a template class (with State and Input as template parameters), I 
have the following (private) member:

State[][Tuple!(const(State), const(Input))] transitions;

It works well enough, but for some reason I can't access its length 
attribute...? (If I define other simpler, similar private attributes, 
such as uint[uint], I can access their length in the same location 
where transition.length fails.)

I get an error message that seems to indicate that DMD is looking for a 
global identifier. I've tried instantiating with different types, e.g., 
uint.

Am I doing something illegal?-)

-- 
Magnus Lie Hetland
http://hetland.org
Mar 12 2012
next sibling parent reply "bearophile" <bearophileHUGS lycos.com> writes:
Magnus Lie Hetland:

 Am I doing something illegal?-)

It looks legal. As usual I suggest to minimize the code, and show us the reduced case that shows the problem :-) Bye, bearophile
Mar 12 2012
parent reply =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 03/12/2012 08:59 AM, bearophile wrote:
 Magnus Lie Hetland:

 Am I doing something illegal?-)

It looks legal. As usual I suggest to minimize the code, and show us the reduced case that shows the problem :-) Bye, bearophile

Let's please also see the exact error message. "an error message that seems to indicate that DMD is looking for a global identifier" is not clear to mortals like myself. :) Ali
Mar 12 2012
parent reply Magnus Lie Hetland <magnus hetland.org> writes:
On 2012-03-13 02:27:46 +0000, Simen Kjærås said:

 Weird.

Indeed. Would've thought const AA keys would be reasonable. (In Python they're *required*... :)
 You get a different error message from what I get.
 My reduced code:

 http://d.puremagic.com/issues/show_bug.cgi?id=7695

I guess this issue then covers both (despite the different error messages)? I'll just leave this alone (i.e., not submit any additional tickets), then (and cast away the constness for now; seems to help). -- Magnus Lie Hetland http://hetland.org
Mar 13 2012
parent Magnus Lie Hetland <magnus hetland.org> writes:
On 2012-03-13 14:24:37 +0000, H. S. Teoh said:

 Indeed. Would've thought const AA keys would be reasonable. (In
 Python they're *required*... :)

I'm of the opinion that AA keys should be *implicitly* immutable.

Seconded, whole-heartedly. -- Magnus Lie Hetland http://hetland.org
Mar 13 2012
prev sibling next sibling parent Andrej Mitrovic <andrej.mitrovich gmail.com> writes:
On 3/12/12, Ali =C7ehreli <acehreli yahoo.com> wrote:
 Let's please also see the exact error message. "an error message that
 seems to indicate that DMD is looking for a global identifier" is not
 clear to mortals like myself. :)

He probably means something like this: struct State { } struct Input { } State[][Tuple!(const(State), const(Input))] transitions; void main() { writeln(transitions.length); } test.d(20): Error: undefined identifier module test.length Note that typeid doesn't work either: writeln(typeid(transitions)); D:\DMD\dmd2\windows\bin\..\..\src\druntime\import\object.di(507): Error: can only initialize const member key inside constructor This seems to be an issue related with const. Without const both calls work= .
Mar 12 2012
prev sibling next sibling parent =?utf-8?Q?Simen_Kj=C3=A6r=C3=A5s?= <simen.kjaras gmail.com> writes:
On Mon, 12 Mar 2012 19:20:07 +0100, Andrej Mitrovic  =

<andrej.mitrovich gmail.com> wrote:

 On 3/12/12, Ali =C3=87ehreli <acehreli yahoo.com> wrote:
 Let's please also see the exact error message. "an error message that=


 seems to indicate that DMD is looking for a global identifier" is not=


 clear to mortals like myself. :)

He probably means something like this: struct State { } struct Input { } State[][Tuple!(const(State), const(Input))] transitions; void main() { writeln(transitions.length); } test.d(20): Error: undefined identifier module test.length Note that typeid doesn't work either: writeln(typeid(transitions)); D:\DMD\dmd2\windows\bin\..\..\src\druntime\import\object.di(507): Error: can only initialize const member key inside constructor This seems to be an issue related with const. Without const both calls=

 work.

Weird. You get a different error message from what I get. My reduced code: struct Bar { const int t; } void main( ) { int[Bar] a; int n =3D a.length; } Error message: Assertion failure: 'impl' on line 4407 in file 'mtype.c' abnormal program termination http://d.puremagic.com/issues/show_bug.cgi?id=3D7695
Mar 12 2012
prev sibling parent "H. S. Teoh" <hsteoh quickfur.ath.cx> writes:
On Tue, Mar 13, 2012 at 10:02:02AM +0100, Magnus Lie Hetland wrote:
 On 2012-03-13 02:27:46 +0000, Simen Kjærås said:
 
Weird.

Indeed. Would've thought const AA keys would be reasonable. (In Python they're *required*... :)

I'm of the opinion that AA keys should be *implicitly* immutable. It makes no sense to have mutable AA keys: int[] mykey = [1,2,3,4]; string[int[]] aa; aa[mykey] = "abc"; mykey[0] = 2; // monkey business: mykey has changed but aa // doesn't know about it assert(([1,2,3,4] in aa) !is null); // this will fail But requiring the user to constantly type overly-long type specs like string[immutable int[]] just makes AA's annoying to use, especially if unqualified key types are always illegal. T -- Your inconsistency is the only consistent thing about you! -- KD
Mar 13 2012