On Wednesday, 28 December 2011 at 22:39:15 UTC, Timon Gehr wrote:
On 12/28/2011 11:12 PM, foobar wrote:
On Wednesday, 28 December 2011 at 21:17:49 UTC, Timon Gehr
wrote:
I was educated enough not to make that mistake, because I
read the
entire language specification before deciding the language
was awesome
and downloading the compiler. I find it strange that the
product
should be made less usable because we do not expect users to
read the
manual. But it is of course a valid point.
That's awfully optimistic to expect people to read the manual.
Well, if the alternative is slowly butchering the language I
will be awfully optimistic about it all day long.
There is nothing wrong with operating at the code unit level.
Efficient slicing is very desirable.
I agree that it's useful. It is however the incorrect
abstraction level
when you need a "string" which is by far the common case in
user code.
I would not go as far as to call it 'incorrect'.
i.e. if I need a name variable in a class: codeUnit[] name; //
bug!
string Name; // correct
From a pragmatic viewpoint it does not matter because if string
is used like this, then codeUnit[] does exactly the same thing.
Nobody forces anyone to index or slice into a string variable
when they don't need that functionality. All engineers have to
work with leaky abstractions. Why is it such a big deal?
I expect that most uses of code-unit arrays should be in the
standard
library anyway since it provides the string manipulation
routines. It
all boils down to making the common case trivial and the rare
case
possible. You can use the underlying data structure (code
units) if you
need it but the default "string" is what people expect when
thinking
about what such a type does (a string of letters). D's already
80% there
since Phobos already treats strings as bi-directional ranges of
code-points which is much closer to the mental image of a
string of
letters, so I think this is about bringing the current design
to its
final conclusion.
Well, that mental image is just not the right one when dealing
with Unicode.
Exactly. It is acting less and less like an array of code
units. But
it *is* an array of code units. If the general consensus is
that we
need a string data type that acts at a different abstraction
level by
default (with which I'd disagree, but apparently I don't have
a
popular opinion here), then we need a string type in the
standard
library to do that. Changing the language so that an array of
code
units stops behaving like an array of code units is not a
solution.
I agree that we should not break T[] for any T and instead
introduce a
library type. While I personally believe that such a change
will expose
hidden bugs (certainly when unaware programmers treat string
as ASCII
and the product is later on localized), it's a big disturbance
in
people's code and it's worth a consideration if the benefit
worth the
costs. Perhaps, some middle ground could be found such that
existing
code can rely on existing behavior and the new library type
will be an
opt-in.
What will such a type offer, except that it disallows indexing
and slicing?
From a pragmatic view point people can also continue programming
in C++ instead of investing a lot of effort learning a new
language.
The only difference between programming languages is the human
interface aspect. Anything you can program with D you could also
do in assembly yet you prefer D because it's more convenient. In
that regard, a code-unit array is definitely worse than a string
type.
A programmer can choose to either change his 'naive' mental image
or change the programming language. Most will do the latter.
Computers need to adapt and be human friendly, not vice-versa.
