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Bo Persson
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 Posted: Mon May 21, 2007 7:04 am Post subject: C++0x container constructors for DefaultConstructible object |
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I notice in the draft N2284 that sequence containers have had one
constructor split in two. We now have (for list<T>):
explicit list(size_type n);
list(size_type n, const T& value, const Allocator& = Allocator());
How come the first type of constructor doesn't take an allocator
parameter?
Bo Persson
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Howard Hinnant
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| Posted: Mon May 21, 2007 8:59 pm Post subject: Re: C++0x container constructors for DefaultConstructible ob |
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In article <5b91g3F2rt1iiU1 (AT) mid (DOT) individual.net>,
bop (AT) gmb (DOT) dk ("Bo Persson") wrote:
| Quote: | I notice in the draft N2284 that sequence containers have had one
constructor split in two. We now have (for list<T>):
explicit list(size_type n);
list(size_type n, const T& value, const Allocator& = Allocator());
How come the first type of constructor doesn't take an allocator
parameter?
|
Mainly just history. People have never been able to say:
std::list<T, A> c(n, A());
And I've never heard any requests for that functionality. So I didn't
add it. It easily could be added. Is there demand for it? Would you
be willing to write a short paper or defect report with detailed
proposed wording relative to N2284?
-Howard
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Bo Persson
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| Posted: Tue May 22, 2007 3:44 am Post subject: Re: C++0x container constructors for DefaultConstructible ob |
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Howard Hinnant wrote:
:: In article <5b91g3F2rt1iiU1 (AT) mid (DOT) individual.net>,
:: bop (AT) gmb (DOT) dk ("Bo Persson") wrote:
::
::: I notice in the draft N2284 that sequence containers have had one
::: constructor split in two. We now have (for list<T>):
:::
::: explicit list(size_type n);
::: list(size_type n, const T& value, const Allocator& = Allocator());
:::
::: How come the first type of constructor doesn't take an allocator
::: parameter?
::
:: Mainly just history. People have never been able to say:
::
:: std::list<T, A> c(n, A());
::
:: And I've never heard any requests for that functionality. So I
:: didn't add it. It easily could be added. Is there demand for it?
:: Would you be willing to write a short paper or defect report with
:: detailed proposed wording relative to N2284?
::
I was really just curious about why one constructor breaks the
pattern. Having already written a defect report for for strings
(#614), I noticed that other containers now also deviate from the
container requirements in 23.1/9, where it says that constructors
should all take an Allocator& argument. Except when they don't?
I can also guess that the new constructor should default construct the
container's allocator member, but haven't found that it says so
anywhere. Did I miss this requirement, or is it just obvious anyway?
Bo Persson
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Pete Becker
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| Posted: Tue May 22, 2007 3:45 am Post subject: Re: C++0x container constructors for DefaultConstructible ob |
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Howard Hinnant wrote:
| Quote: | In article <5b91g3F2rt1iiU1 (AT) mid (DOT) individual.net>,
bop (AT) gmb (DOT) dk ("Bo Persson") wrote:
I notice in the draft N2284 that sequence containers have had one
constructor split in two. We now have (for list<T>):
explicit list(size_type n);
list(size_type n, const T& value, const Allocator& = Allocator());
How come the first type of constructor doesn't take an allocator
parameter?
Mainly just history. People have never been able to say:
std::list<T, A> c(n, A());
And I've never heard any requests for that functionality. So I didn't
add it. It easily could be added. Is there demand for it? Would you
be willing to write a short paper or defect report with detailed
proposed wording relative to N2284?
|
Please, not a "defect report." Defect reports apply only to published
standards, and they invoke a formal response process.
--
-- Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com)
Author of "The Standard C++ Library Extensions: a Tutorial and
Reference." (www.petebecker.com/tr1book)
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[ comp.std.c++ is moderated. To submit articles, try just posting with ]
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