Re: The members of ::std::initializer_list

[Victor Bazarov]

On 5/5/2015 11:05 AM, Stefan Ram wrote:
> Can someone explain why the type ::std::initializer_list
> does not have some convenience members that some programmers
> might expect? IIRC, it's members can be stored in ROM, but
> why does an ::std::initializer_list l has
>
> l.begin()
> ::std::begin( l )
>
> but no
>
> l.cbegin()
> ::std::cbegin( l )
>
> , and why is there no
>
> l[ size_t ]
> l.at( size_t )
>
> ?

Most likely *because* those were deemed unnecessary or unnecessarily
difficult to implement. An initializer list is not a container. Its
purpose is to assist initialization, that's all.

I hope you're not going to ask next why pointers and arrays don't have
members like 'cbegin' or 'rend'...

Besides, the rationales behind language design decisions are discussed
in comp.std.c++. Consider posting there, if you are really interested
and not just venting some kind of frustration, OK?

V
--
I do not respond to top-posted replies, please don't ask

[Victor Bazarov]

On 5/5/2015 12:07 PM, Stefan Ram wrote:

> Victor Bazarov <v.ba...@comcast.invalid> writes:
>> I hope you're not going to ask next why pointers and arrays don't have
>> members like 'cbegin' or 'rend'...
>

> Well, for arrays ...
>
> #include <iostream>
> #include <ostream>
> #include <memory>
> #include <vector>
>
> int main()
> { ::std::cout << __cplusplus << '\n';
> ::std::vector< int >a{ 1, 2, 3 };
> for( auto p = ::std::cbegin( a ); p != ::std::cend( a ); ++p )

Yes, but those are not *members*.

> ::std::cout << *p << '\n'; }
>
> 201402
> 1
> 2
> 3
>
> And all of a sudden, it also works with initializer lists!
>
> My problem was actually that I did not manage before to force
> my compiler into C++14 mode before!
>
> #include <iostream>
> #include <ostream>
> #include <memory>
> #include <initializer_list>
>
> int main()
> { ::std::cout << __cplusplus << '\n';
> ::std::initializer_list< int >a{ 1, 2, 3 };
> for( auto p = ::std::cbegin( a ); p != ::std::cend( a ); ++p )
> ::std::cout << *p << '\n'; }
>
> 201402
> 1
> 2
> 3

[Bo Persson]

On 2015-05-05 17:05, Stefan Ram wrote:
> Can someone explain why the type ::std::initializer_list
> does not have some convenience members that some programmers
> might expect? IIRC, it's members can be stored in ROM, but
> why does an ::std::initializer_list l has
>
> l.begin()
> ::std::begin( l )
>
> but no
>
> l.cbegin()
> ::std::cbegin( l )
>
> , and why is there no
>

Part of this is likely just an historical accident. In C++98 none of the
containers had cbegin or cend. When they were added by one C++11
proposal, std::initializer_list was in another proposal, and apparently
nobody thought about cross checking that.

The free functions, added even later, should work in all cases.


Bo Persson

[Juha Nieminen]

Victor Bazarov <v.ba...@comcast.invalid> wrote:
> Besides, the rationales behind language design decisions are discussed
> in comp.std.c++. Consider posting there, if you are really interested
> and not just venting some kind of frustration, OK?

Dispersing conversation about the same topic (ie. C++) into several
groups doesn't help anybody. It's not like this group gets thousands
of posts every day and there's need to alleviate the flooding.

--- news://freenews.netfront.net/ - complaints: ne...@netfront.net ---

[Victor Bazarov]

On 5/6/2015 4:41 AM, Juha Nieminen wrote:
> Victor Bazarov <v.ba...@comcast.invalid> wrote:
>> Besides, the rationales behind language design decisions are discussed
>> in comp.std.c++. Consider posting there, if you are really interested
>> and not just venting some kind of frustration, OK?
>
> Dispersing conversation about the same topic (ie. C++) into several
> groups doesn't help anybody. It's not like this group gets thousands
> of posts every day and there's need to alleviate the flooding.

Welcome back! I've missed you. It's not the same newsgroup without you.