The Thermopylae excerpt of TDPL available online

[Andrei Alexandrescu]

Leandro Lucarella wrote:
> Leandro Lucarella, el 29 de octubre a las 13:21 me escribiste:
>> Andrei Alexandrescu, el 28 de octubre a las 23:38 me escribiste:
>>> It's a rough rough draft, but one for the full chapter on arrays,
>>> associative arrays, and strings.
>>>
>>> http://erdani.com/d/thermopylae.pdf
>>>
>>> Any feedback is welcome. Thanks!
>> It looks very nice. A small error in 4.1.7 first code block:
>>
>> auto a = new double[4];          // must be already allocated
>> auto a1 = [ 0.5, -0.5, 1.5, 2 ];
>> auto a2 = [ 3.5, 5.5, 4.5, -1 ];
>> a[] = (a1[] + a2[]) / 2;         // take the average of b and c
>>                                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>                                    take the average of a1 and a2?
>>
>> (I think it would be easier to follow using b and c though ;)
> 
> BTW, it looks like array literals will be dynamic arrays, from the code in
> your book. Can you or Walter explain why this is better to make array
> literals statically stored immutable memory like strings (which adds an
> inconsistency to the language)? Is this just to avoid [1,2,3].dup; when
> you want to get a dynamic array from an array literal or is there other
> reasons?

I don't have a better explanation than the excerpt:

Beware, however: if you replace @int[3]@ above with @auto@, @a@'s type
will be deduced  as @int[]@, not @int[3]@.  Although  it seems logical
that the type of  \cc{[1, 2, 3]} should be @int[3]@ which  in a way is
more  ``precise'' than  @int[]@, it  turns out  that dynamically-sized
arrays are used  much more often than fixed-size  arrays, so insisting
on fixed-size  array literals would  have been a  usability impediment
and  a  source  of  unpleasant  surprises.  Effectively,  the  use  of
literals would  have prevented the gainful  use of @auto at .   As it is,
array literals are @T[]@ by  default, and @T[n]@ if you \emph{ask} for
that specific  type and  if @n@  matches the number  of values  in the
literal (as the code above shows).


Andrei