boost any questions and praise

newer
Header only libraries, why not all?

Alan Tennant

30 Jan 2010 30 Jan '10

11:59 a.m.

Firstly. Thank you very much team Boost, it looks like it will be very useful and solve many of my coding problems. I can create an any boost::any a1; I can assign something to it a1 = string1; I can get it back out later std::cout<<any_cast<std::string>(a1); A boost any has a "type()" method. However this produced an error. std::cout<<any_cast<a1.type()>(a1);

Attachments:

attachment.html (text/html — 454 bytes)

Show replies by date

Steven Watanabe

30 Jan 30 Jan

12:58 p.m.

AMDG Alan Tennant wrote:

...

Firstly. Thank you very much team Boost, it looks like it will be very useful and solve many of my coding problems.

I can create an any boost::any a1;

I can assign something to it a1 = string1;

I can get it back out later std::cout<<any_cast<std::string>(a1);

A boost any has a "type()" method.

However this produced an error.

std::cout<<any_cast<a1.type()>(a1);

Template parameters have to be types. The result of a1.type() is a std::type_info object. In Christ, Steven Watanabe

Alan Tennant

6:30 p.m.

Thanks for the info. Can it be done (at all, at the moment, elegantly, practically, by turning a std::type_info into a type) ? On 30 January 2010 19:58, Steven Watanabe <watanabesj@gmail.com> wrote:

...

AMDG

Alan Tennant wrote:

...
Firstly. Thank you very much team Boost, it looks like it will be very useful and solve many of my coding problems.

I can create an any boost::any a1;

I can assign something to it a1 = string1;

I can get it back out later std::cout<<any_cast<std::string>(a1);

A boost any has a "type()" method.

However this produced an error.

std::cout<<any_cast<a1.type()>(a1);

Template parameters have to be types. The result of a1.type() is a std::type_info object.

In Christ, Steven Watanabe

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

Steven Watanabe

6:51 p.m.

AMDG Alan Tennant wrote:

...

Thanks for the info. Can it be done (at all, at the moment, elegantly, practically, by turning a std::type_info into a type) ?

It can't be done. Types must be known at compile time, but std::type_info is only known at runtime. In Christ, Steven Watanabe

Peter Foelsche

1 Feb 1 Feb

2:10 p.m.

see attached Peter "Alan Tennant" <alan2here@gmail.com> wrote in message news:a557f5fb1001301059h1dfc32davd917a47d8c598a05@mail.gmail.com... Firstly. Thank you very much team Boost, it looks like it will be very useful and solve many of my coding problems. I can create an any boost::any a1; I can assign something to it a1 = string1; I can get it back out later std::cout<<any_cast<std::string>(a1); A boost any has a "type()" method. However this produced an error. std::cout<<any_cast<a1.type()>(a1); ------------------------------------------------------------------------------ _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

Alan Tennant

5:39 p.m.

Thanks :¬) I can't test it until tomorrow but it looks great. This appears to take boost::any closer to boost::variant. << support is most useful. I presume they still cast back to the original object in the same way that boost::any does and any non standard object they contain that will work in a stream will now work inside the boost::any. Is this going to be an official update or just a branch for me. Can I get a mention for inspiring the idea? Whats the empty struct for in main? Thanks for the info about Variant being faster. Especially with this new change it looks as if boost::any and boost::variant can be interchanged quite easily. On 1 February 2010 21:10, Peter Foelsche <foelsche@sbcglobal.net> wrote:

...

see attached

Peter

"Alan Tennant" <alan2here@gmail.com> wrote in message news:a557f5fb1001301059h1dfc32davd917a47d8c598a05@mail.gmail.com... Firstly. Thank you very much team Boost, it looks like it will be very useful and solve many of my coding problems.

I can create an any boost::any a1;

I can assign something to it a1 = string1;

I can get it back out later std::cout<<any_cast<std::string>(a1);

A boost any has a "type()" method.

However this produced an error.

std::cout<<any_cast<a1.type()>(a1);

------------------------------

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

Roman Perepelitsa

2 Feb 2 Feb

2:48 a.m.

2010/2/2 Alan Tennant <alan2here@gmail.com>

...

<< support is most useful. I presume they still cast back to the original object in the same way that boost::any does and any non standard object they contain that will work in a stream will now work inside the boost::any.

Adobe poly <http://stlab.adobe.com/group__poly__related.html> library might be better for your use case. It's like boost::any with ability to add additional operators (e.g. operator<<). Roman Perepelitsa.

Peter Foelsche

9:13 a.m.

...

"Alan Tennant" <alan2here@gmail.com> wrote in message news:a557f5fb1002011639i142be9a0j29205e3ae643a6a9@mail.gmail.com... Thanks :¼)

I can't test it until tomorrow but it looks great. This appears to take boost::any closer to boost::variant.

<< support is most useful. I presume they still cast back to the original object in the same way that boost::any does and any non standard object they contain that will work in a stream will now work inside the boost::any.

Is this going to be an official update or just a branch for me.

I'm still unclear how to work with the people from boost. Usually I'm posting something here and hope for an answer.

...

Can I get a mention for inspiring the idea?

Whats the empty struct for in main?

just for testing what happens if some class does not provide the << operator. Peter

...

Thanks for the info about Variant being faster. Especially with this new change it looks as if boost::any and boost::variant can be interchanged quite easily.

On 1 February 2010 21:10, Peter Foelsche <foelsche@sbcglobal.net> wrote:

see attached

Peter "Alan Tennant" <alan2here@gmail.com> wrote in message news:a557f5fb1001301059h1dfc32davd917a47d8c598a05@mail.gmail.com... Firstly. Thank you very much team Boost, it looks like it will be very useful and solve many of my coding problems.

I can create an any boost::any a1;

I can assign something to it a1 = string1;

I can get it back out later std::cout<<any_cast<std::string>(a1);

A boost any has a "type()" method.

However this produced an error.

std::cout<<any_cast<a1.type()>(a1);

------------------------------------------------------------------------ --------

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

------------------------------------------------------------------------ --------

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

5616

Age (days ago)

5619

Last active (days ago)

List overview

Download

7 comments

4 participants

participants (4)

Alan Tennant
Peter Foelsche
Roman Perepelitsa
Steven Watanabe