• d-bugmail puremagic.com Apr 18 2008
• d-bugmail puremagic.com Apr 18 2008

http://d.puremagic.com/issues/show_bug.cgi?id=2006

           Summary: Appending empty array using ~= doesn't work
           Product: D
           Version: 2.012
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: bartosz relisoft.com


I have an empty array of arrays of string aas. I append to it an empty array of
string. The result should be an array aas of length one. 

string [][] aas = [];
aas ~= cast (string []) [];
writefln ("%d", aas.length);
aas = aas ~ cast (string []) [];
writefln ("%d", aas.length);

It works correctly when using assignment and concatenation, but id doesn't when
using the combined operator ~=. In the latter case, the length of array remains
zero.


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http://d.puremagic.com/issues/show_bug.cgi?id=2006





------- Comment #1 from wbaxter gmail.com  2008-04-18 14:46 -------
That's funny I was just about to file this one myself a couple of days ago, BUT
then I decided that it probably isn't really a bug.

[] could be an empty array of any type.  So the compiler is interpreting it as
an empty string[][], not an empty string[].  You have a T[], you concat an
empty T[],  your original array isn't supposed to change.

I will agree it's not the most useful of behaviors, and the doc could certainly
be clearer about what will happen in such a case, but I don't think its
actually a bug.  It's just the compiler interpreting [] in a not-so-useful
manner.  If you type a literal "~= []" in the code then clearly you want
something to happen.

The workaround is to use "~= [[]]" instead.


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