Re: [Cppcms-users] Compile error: traits is not a template

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Also, when I said deep copy, I mean the following codes:

for(size_t i = 0;i<in.values_.size();i++)
  a[i]=*in.values_[i];

陈抒
Best regards
http://blog.csdn.net/sheismylife

On Sat, Sep 1, 2012 at 9:24 PM, 陈抒 <csf...@gm...> wrote:

> I tried you codes the first time. It can't be compiled.
>
> $ make
> Scanning dependencies of target cppweb
> [  3%] Building CXX object bin/CMakeFiles/cppweb.dir/groups.cpp.o
> In file included from /home/chenshu/work/kaimei/cppweb/src/groups.cpp:1:0:
> /home/chenshu/work/kaimei/cppweb/include/groups.h: In static member
> function ‘static void
> cppcms::json::traits<kaimei::groups>::set(cppcms::json::value&, const
> kaimei::groups&)’:
> /home/chenshu/work/kaimei/cppweb/include/groups.h:39:60: error: invalid
> initialization of non-const reference of type ‘cppcms::json::array& {aka
> std::vector<cppcms::json::value>&}’ from an rvalue of type ‘void’
>  make[2]: *** [bin/CMakeFiles/cppweb.dir/groups.cpp.o] Error 1
> make[1]: *** [bin/CMakeFiles/cppweb.dir/all] Error 2
> make: *** [all] Error 2
>
> line 39 is :
>  cppcms::json::array &a=v.at("values",cppcms::json::array());
>
> I upgraded CppCMS to latest version, also read your API document.
> It seems your 'at' member function return 'void'
>
> 陈抒
> Best regards
> http://blog.csdn.net/sheismylife
>
>
> On Sat, Sep 1, 2012 at 9:15 PM, Artyom Beilis <art...@ya...> wrote:
>
>> You hadn't read my code correctly
>>
>> cppcms::json::array &a=v.at("values",cppcms::json::array());
>>
>> a is a reference and you fill it.
>>
>> Anyway read the cppcms::json::value reference documentation for further
>> details
>>
>> Artyom Beilis
>> --------------
>> CppCMS - C++ Web Framework:   http://cppcms.com/
>> CppDB - C++ SQL Connectivity: http://cppcms.com/sql/cppdb/
>>
>>   ------------------------------
>> *From:* 陈抒 <csf...@gm...>
>> *To:* Artyom Beilis <art...@ya...>;
>> cpp...@li...
>> *Sent:* Saturday, September 1, 2012 3:32 PM
>>
>> *Subject:* Re: [Cppcms-users] Compile error: traits is not a template
>>
>> I changed your codes a bit.
>> namespace cppcms {
>>   namespace json {
>>
>>     template<>
>>       struct traits<kaimei::groups> {
>>
>>        static void set(value &v, kaimei::groups const& in) {
>> v.set("size", in.size());
>> cppcms::json::array a;
>>  a.resize(in.values_.size());
>> for(size_t i = 0; i < in.values_.size(); i++) {
>>   a[i]=*in.values_[i];
>> }
>> v.set("values", a);
>>       }
>>     };
>>
>>   }
>> }
>>
>> Two issues:
>> 1. This way is not efficient, a lot of deep copy would occur when copying
>> vector from array.
>> My original way is very simple, create a stringstream object, groups
>> object converts all member variables into string, append them to
>> stringstream. It does not looks elegant, but faster.
>> 2. It doesn't work. I got an exception:
>> cppcms::json::bad_cast:  error converting from object
>>
>>
>> 陈抒
>> Best regards
>> http://blog.csdn.net/sheismylife
>>
>>
>> On Sat, Sep 1, 2012 at 5:41 PM, Artyom Beilis <art...@ya...>wrote:
>>
>> Because shared_ptr<group> is not specialized for traits...
>>
>> You need manually create an array and sets its memebers.i.e
>>
>> Something like that:
>>
>> cppcms::json::array &a=v.at("values",cppcms::json::array());
>> a.resize(in.values_.size());
>> for(size_t i = 0;i<in.values_.size();i++)
>>   a[i]=*in.values_[i];
>>
>>
>>
>>
>>
>> Artyom Beilis
>> --------------
>> CppCMS - C++ Web Framework:   http://cppcms.com/
>> CppDB - C++ SQL Connectivity: http://cppcms.com/sql/cppdb/
>>
>>
>>
>> >________________________________
>> > From: 陈抒 <csf...@gm...>
>> >To: Artyom Beilis <art...@ya...>;
>> cpp...@li...
>> >Sent: Saturday, September 1, 2012 10:05 AM
>> >Subject: Re: [Cppcms-users] Compile error: traits is not a template
>> >
>> >
>> >Thank you. But I see new error.
>> >groups.h file:
>> >
>> >
>> >#ifndef __GROUPS_H
>> >#define __GROUPS_H
>> >
>> >
>> >#include <vector>
>> >#include <boost/shared_ptr.hpp>
>> >#include "group.h"
>> >
>> >
>> >namespace kaimei{
>> >
>> >
>> >  class groups{
>> >  public:
>> >    typedef std::vector<boost::shared_ptr<group> >::iterator iterator;
>> >    typedef std::vector<boost::shared_ptr<group> >::const_iterator
>> const_iterator;
>> >
>> >
>> >    void add(boost::shared_ptr<group> g);
>> >
>> >
>> >    bool empty() const;
>> >
>> >
>> >    unsigned int size() const;
>> >
>> >
>> >    std::string json_string() const;
>> >
>> >    friend class cppcms::json::traits<kaimei::groups>;
>> >
>> >
>> >  private:
>> >    std::vector<boost::shared_ptr<kaimei::group> > values_;
>> >  };
>> >
>> >
>> >}
>> >
>> >
>> >namespace cppcms {
>> >  namespace json {
>> >
>> >
>> >    template<>
>> >      struct traits<kaimei::groups> {
>> >
>> >
>> >      static void set(value &v, kaimei::groups const& in) {
>> >v.set("size", in.size());
>> >v.set("values", in.values_);
>> >      }
>> >    };
>> >
>> >
>> >  }
>> >}
>> >
>> >
>> >#endif
>> >
>> >
>> >
>> >
>> >error message:
>> >  3%] Generating ../../src/view/welcome.cpp, ../../src/view/home.cpp,
>> ../../src/view/gprs_message.cpp, ../../src/view/gprs_manager.cpp,
>> ../../src/view/gprs_password.cpp, ../../src/view/gprs_log.cpp,
>> ../../src/view/register_client.cpp, ../../src/view/gprsConfig.cpp,
>> ../../src/view/login.cpp, ../../src/view/group_management.cpp
>> >[  6%] Building CXX object bin/CMakeFiles/cppweb.dir/groups.cpp.o
>> >In file included from
>> /home/chenshu/work/kaimei/cppweb/include/group.h:5:0,
>> >                 from
>> /home/chenshu/work/kaimei/cppweb/include/groups.h:6,
>> >                 from /home/chenshu/work/kaimei/cppweb/src/groups.cpp:1:
>> >/usr/include/cppcms/json.h: In member function ‘void
>> cppcms::json::value::set_value(const T&) [with T =
>> boost::shared_ptr<kaimei::group>]’:
>> >/usr/include/cppcms/json.h:604:5:   instantiated from ‘static void
>> cppcms::json::traits<std::vector<T> >::set(cppcms::json::value&, const
>> std::vector<T>&) [with T = boost::shared_ptr<kaimei::group>]’
>> >/usr/include/cppcms/json.h:247:4:   instantiated from ‘void
>> cppcms::json::value::set_value(const T&) [with T =
>> std::vector<boost::shared_ptr<kaimei::group> >]’
>> >/usr/include/cppcms/json.h:316:4:   instantiated from
>> ‘cppcms::json::value::value(const T&) [with T =
>> std::vector<boost::shared_ptr<kaimei::group> >]’
>> >/usr/include/cppcms/json.h:352:4:   instantiated from ‘void
>> cppcms::json::value::set(const char*, const T&) [with T =
>> std::vector<boost::shared_ptr<kaimei::group> >]’
>> >/home/chenshu/work/kaimei/cppweb/include/groups.h:39:28:   instantiated
>> from here
>> >/usr/include/cppcms/json.h:247:4: error: incomplete type
>> ‘cppcms::json::traits<boost::shared_ptr<kaimei::group> >’ used in nested
>> name specifier
>> >make[2]: *** [bin/CMakeFiles/cppweb.dir/groups.cpp.o] Error 1
>> >make[1]: *** [bin/CMakeFiles/cppweb.dir/all] Error 2
>> >make: *** [all] Error 2
>> >
>> >
>> >陈抒
>> >Best regards
>> >http://blog.csdn.net/sheismylife
>> >
>> >
>> >
>> >On Sat, Sep 1, 2012 at 2:34 PM, Artyom Beilis <art...@ya...>
>> wrote:
>> >
>> >>
>> >>
>> >>>But I got error when compiling another class. It has group.h and
>> group.cpp file.
>> >>>
>> >>>
>> >>>#ifndef __GROUP_H
>> >>>#define __GROUP_H
>> >>>
>> >>>
>> >>>#include <string>
>> >>>
>> >>>
>> >>>namespace kaimei{
>> >>>...
>> >>
>> >>}
>> >>>
>> >>>
>> >>>namespace cppcms {
>> >>>  namespace json {
>> >>>    template<>
>> >>>      struct traits<kaimei::group> {
>> >>>...
>> >>>      }
>> >>>  }
>> >>>}
>> >>>
>> >>>
>> >>>
>> >>> [snip]
>> >>
>> >>>
>> >>>I am not good at template programming. Why did this happen?
>> >>>
>> >>
>> >>You can't specialize undefined struct - you need to include
>> <cppcms/json.h>
>> >>header. It provides the original traits struct and than you specialize
>> it for
>> >>your type of class
>> >>
>> >>
>> >>
>> >>>
>> >>>陈抒
>> >>>Best regards
>> >>>http://blog.csdn.net/sheismylife
>> >>>
>> >>
>> >>Regards,
>> >>Artyom
>> >>
>> >>
>>
>> >>------------------------------------------------------------------------------
>> >>Live Security Virtual Conference
>> >>Exclusive live event will cover all the ways today's security and
>> >>threat landscape has changed and how IT managers can respond.
>> Discussions
>> >>will include endpoint security, mobile security and the latest in
>> malware
>> >>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>> >>_______________________________________________
>> >>Cppcms-users mailing list
>> >>Cpp...@li...
>> >>https://lists.sourceforge.net/lists/listinfo/cppcms-users
>> >>
>> >
>>
>> >------------------------------------------------------------------------------
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>> >_______________________________________________
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>> >https://lists.sourceforge.net/lists/listinfo/cppcms-users
>> >
>> >
>> >
>>
>>
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>>
>>
>>
>>
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>> threat landscape has changed and how IT managers can respond. Discussions
>> will include endpoint security, mobile security and the latest in malware
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>> Cppcms-users mailing list
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>>
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>>
>>
>> ------------------------------------------------------------------------------
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>> Exclusive live event will cover all the ways today's security and
>> threat landscape has changed and how IT managers can respond. Discussions
>> will include endpoint security, mobile security and the latest in malware
>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
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>> Cppcms-users mailing list
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>