Array type conversion

[Mark Burnett]

I have spent much of the last couple of weeks trying to choose a language in which to write the code for my PhD thesis (in computational physics).  I had very nearly decided on using c++, when yesterday I stumbled upon D.  So far I'm ecstatic about it's feature set.

Still there are one or two things that strike me as odd:  in particular that arrays of a derived type can be converted to an array of a base type.  As pointed out by Marshall Cline, [http://www.parashift.com/c++-faq-lite/proper-inheritance.html#faq-21.4] this is dangerous.  Is this possibly a holdover from c++?  It is explicitly mentioned in the array page that they behave this way, so I am not convinced that is the case.

Fortunately not all of the problems associated with doing this in c++ exist in d (see attached code).  What d seems to do is treat all derived[] as base[], which is silly because if i want a base[], I would just declare it that way.  Asking for a derived[] is how I say that I  *only* want derived objects in there.

The attached code generates this output using gdc 0.23 on OSX:
Here are the different apples we have:
A P P L E -- Red
A P P L E -- Red
A P P L E -- Red
Orange -- Orange
A P P L E -- Red

Please, keep in mind that this test is the first d I have written, and I don't claim to understand the language.  Array type promotion just seems odd to include, and I would like to understand the motivation for doing so.
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