Just got the TDPL book and it's a great read! I learn best when typing out the code myself, so I decided to make a single VisualD project and put the different exercises in separate modules. I am having problems with sort in std.algorithms - well, actually it appears to be a closure problem when sort calls my delegate.

Here's a sample of the problem - in main.d I have

//------------------
module main;
import std.algorithm;
void main() {
	uint[string] counts = [ "a":4, "b":5, "c":3, "d":1 ];
	string[] keys = counts.keys;

	sort!((a, b) { return counts[a] > counts[b]; })(keys);
}
//------------------

Alone this works just fine. But if I add another file called myalgs.d, and put the following in it:

//------------------
module myalgs;
import std.algorithm;
//------------------

Then I get the following exception:

object.Error: Access Violation
----------------
C:\D\dmd2\windows\bin\..\..\src\phobos\std\algorithm.d(7112): mainmain__T8sortImplS14main9__lambda3VE3std9algorithm12SwapStrategy0TAAyaZsortImpl
----------------

Steping through the code it appears that the Access Violation occurs when accessing counts[a].

I am using DMD32 v2.059; my compilation command line looks like:
dmd -g -debug -X -Xf"$(IntDir)\$(TargetName).json" -deps="$(OutDir)\$(ProjectName).dep" -of"$(OutDir)\$(ProjectName).exe_cv" -map "$(INTDIR)\$(SAFEPROJECTNAME).map" -L/NOMAP

Am I doing something wrong here?

thanks for the help!

On Wed, 02 May 2012 11:27:57 -0400, Jabb <jj.jabbaloo@gmail.com> wrote:

> Just got the TDPL book and it's a great read! I learn best when typing out the code myself, so I decided to make a single VisualD project and put the different exercises in separate modules. I am having problems with sort in std.algorithms - well, actually it appears to be a closure problem when sort calls my delegate.

There shouldn't be any closure here, sort is not storing the delegate pointer.

> Here's a sample of the problem - in main.d I have
>
> //------------------
> module main;
> import std.algorithm;
> void main() {
> 	uint[string] counts = [ "a":4, "b":5, "c":3, "d":1 ];
> 	string[] keys = counts.keys;
>
> 	sort!((a, b) { return counts[a] > counts[b]; })(keys);
> }
> //------------------
>
> Alone this works just fine. But if I add another file called myalgs.d, and put the following in it:
>
> //------------------
> module myalgs;
> import std.algorithm;
> //------------------
>
> Then I get the following exception:
>
> object.Error: Access Violation
> ----------------
> C:\D\dmd2\windows\bin\..\..\src\phobos\std\algorithm.d(7112): mainmain__T8sortImplS14main9__lambda3VE3std9algorithm12SwapStrategy0TAAyaZsortImpl
> ----------------
>
> Steping through the code it appears that the Access Violation occurs when accessing counts[a].
>
> I am using DMD32 v2.059; my compilation command line looks like:
> dmd -g -debug -X -Xf"$(IntDir)\$(TargetName).json" -deps="$(OutDir)\$(ProjectName).dep" -of"$(OutDir)\$(ProjectName).exe_cv" -map "$(INTDIR)\$(SAFEPROJECTNAME).map" -L/NOMAP

I can't see any errors, I think this is worthy of a bug report, it's nice and small and self-contained.

http://d.puremagic.com/issues

-Steve

On Wednesday, 2 May 2012 at 15:27:58 UTC, Jabb wrote:

> import std.algorithm;
> void main() {
> 	uint[string] counts = [ "a":4, "b":5, "c":3, "d":1 ];
> 	string[] keys = counts.keys;
>
> 	sort!((a, b) { return counts[a] > counts[b]; })(keys);
> }

Did you try
string[] keys = counts.keys.dup;
?

Sometimes you get weird aliasing issues, as the sort! template
modifies the original array.

On 03/21/2013 01:02 PM, Stefan wrote:
> On Wednesday, 2 May 2012 at 15:27:58 UTC, Jabb wrote:
>
>> import std.algorithm;
>> void main() {
>> uint[string] counts = [ "a":4, "b":5, "c":3, "d":1 ];
>> string[] keys = counts.keys;
>>
>> sort!((a, b) { return counts[a] > counts[b]; })(keys);
>> }
>
> Did you try
> string[] keys = counts.keys.dup;
> ?

That should be ok. Unlike .byKey, .keys is eager; all of the keys are in the returned slice by the time it returns.

Ali

On 05/02/2012 08:27 AM, Jabb wrote:

> Alone this works just fine. But if I add another file called myalgs.d,
> and put the following in it:
>
> //------------------
> module myalgs;
> import std.algorithm;
> //------------------
>
> Then I get the following exception:
>
> object.Error: Access Violation

I can reproduce the bug with 2.062 as well as an earlier development build of 2.063 (a fresher dmd does not build at the moment.)

I have found a workaround: Put the second file later in the dmd command line:

  dmd main.d myalgs.d

Ali