Code doesn't work - why?

[Ali Çehreli via Digitalmars-d-learn]

On 09/17/2014 03:42 AM, Robin wrote:> Hiho,

 > However, I still do not understand why it didn't work for struct value
 > types since I do not perform any mutations on the state objects during
 > execution of the code.

I was a little sloppy with my response. :) What I suspected is still 
correct though. The following are the mutations:

     s0.addTransits(['0' : s1, '1' : s2]);
     s1.addTransits(['0' : s0, '1' : s2]);
     s2.addTransits(['0' : s2, '1' : s2]);

Note that s0 gets a copy of s1 before s1 knows about its transits.

 > When value types are copied bitwise then the associative array should
 > also be copied that way or at least point to the same mapping as the
 > source and thus shouldn't be empty after copying.

There is an issue with uninitialized associative arrays: Although one 
would think that both s1 copies would use the same AA, since the AA is 
uninitialized, they would both initialize it first, having separate AAs.

This is a pretty nasty problem as it matters whether the AA had a single 
record before the copy or not. :(

 > What changes are required in order to make it work with struct value
 > types as well?

I am ashamed to admit that I am not sure how to initialize an AA to the 
empty state. I can do the following though: :)

         this.transits['z'] = this;
         this.transits.remove('z');

Ali