2012/9/26 Jonathan M Davis <jmdavisp...@gmx.com>:
> On Tuesday, September 25, 2012 13:45:50 Michel Fortin wrote:
>> On 2012-09-25 16:38:31 +0000, "Jonathan M Davis" <jmdavisp...@gmx.com> said:
>> > On Tuesday, September 25, 2012 12:28:15 Michel Fortin wrote:
>> >> Although to make things less confusing, I think the built-in language
>> >> tuple should give up its name. It could become a "sequence". Renaming
>> >> the built-in one would certainly be less trouble, as code doesn't refer
>> >> to it by its name, and you can pick a name that fits better with its
>> >> auto-expanding behaviour.
>> >
>> > Not referred to by its name? It's refereed to as TypeTuple all over the
>> > place. It's arguably a bad name, but it would break a _lot_ of code to
>> > change it now.
>> TypeTuple is only a construct allowing you to create a built-in
>> language tuple, one that does not necessarily match the definition of a
>> TypeTuple. The language spec defines a Tuples, TypeTuples, and
>> ExpressionTuples with these words (ironically, using the word
>> "sequence" twice):
>>
>> """
>> If the last template parameter in the TemplateParameterList is declared
>> as a TemplateTupleParameter, it is a match with any trailing template
>> arguments. The sequence of arguments form a Tuple. A Tuple is not a
>> type, an expression, or a symbol. It is a sequence of any mix of types,
>> expressions or symbols.
>>
>> A Tuple whose elements consist entirely of types is called a TypeTuple.
>> A Tuple whose elements consist entirely of expressions is called an
>> ExpressionTuple.
>> """
>> Source: http://dlang.org/template.html
>
> I wasn't aware of that being in the language definition, but it doesn't change
> the fact that they're used and referred to in code as TypeTuple, and renaming
> that would break a lot of code. And it _is_ used for the built-in tuple type,
> regardless of whether the spec considers the terms type tuple and expression
> tuple to refer to distinct entities. Rename the stuff in the spec to whatever
> you like, but the library uses the term TypeTuple, so it _is_ used in code.
>
> - Jonathan M Davis
I like current design - open (built-in, automatically flattened, and
*unpacked*) tuple, and closed (library, be structured, and *packed*)
tuple.
But, the two are often confused, by the word "tuple". It has
introduced badly confusion in many discussions.
To make matters worse, it had often invoked incorrect suggestion that
merging the two into one.
My suggestion is very simple.
1. Change all words "built-in tuple" in the documentation to "built-in
sequence". Then, in the D language world, we can have clarify name for
the built-in one.
2. Introduce new templates, Seq, TypeSeq, and ExpSeq.
template Seq(T...) { alias T Seq; } // identical with
std.typetuple.TypeTuple
template TypeSeq(T...) if (allSatisfy!(isType, T)) { alias T TypeSeq; }
template ExpSeq(T...) if (allSatisfy!(isExpression, T)) { alias T ExpSeq; }
If you really want to a sequence with heterogeneous elements, use
Seq template. Otherwise use TypeSeq or ExpSeq based on your purpose.
Kenji Hara
