Re: [protobuf] C++ modifying field without knowing field accessor at compile time
Yah, after looking back over my problem I refactored and removed the const ref. Just need to take my eyes of the problem for a bit. Thanks for the help. On Monday, October 27, 2014 11:15:32 AM UTC-6, Oliver wrote: > > On 24 October 2014 17:28, Peter Hubner > > wrote: > > All I am trying to achieve is to modify a message on the fly with a set > of > > fields that are supplied to the program at runtime. > > > > simple case: > > // message declared as - const google::protobuf::Message& message > > auto x = reflection->GetDouble(message, field); > > // do some modification to x > > reflection->SetDouble(message, field, x); > > > > my main question is how in the world do I get from a const ref (needed > for > > GetDouble() ) to a pointer (needed for SetDouble() )??? > > const_cast(&message) > > This obviously casts away constness which is something to be careful > about. > If you want to mutate the message, why are you starting with a const ref? > > Oliver > -- You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. To unsubscribe from this group and stop receiving emails from it, send an email to protobuf+unsubscr...@googlegroups.com. To post to this group, send email to protobuf@googlegroups.com. Visit this group at http://groups.google.com/group/protobuf. For more options, visit https://groups.google.com/d/optout.
Re: [protobuf] C++ modifying field without knowing field accessor at compile time
On 24 October 2014 17:28, Peter Hubner wrote: > All I am trying to achieve is to modify a message on the fly with a set of > fields that are supplied to the program at runtime. > > simple case: > // message declared as - const google::protobuf::Message& message > auto x = reflection->GetDouble(message, field); > // do some modification to x > reflection->SetDouble(message, field, x); > > my main question is how in the world do I get from a const ref (needed for > GetDouble() ) to a pointer (needed for SetDouble() )??? const_cast(&message) This obviously casts away constness which is something to be careful about. If you want to mutate the message, why are you starting with a const ref? Oliver -- You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. To unsubscribe from this group and stop receiving emails from it, send an email to protobuf+unsubscr...@googlegroups.com. To post to this group, send email to protobuf@googlegroups.com. Visit this group at http://groups.google.com/group/protobuf. For more options, visit https://groups.google.com/d/optout.
[protobuf] C++ modifying field without knowing field accessor at compile time
All I am trying to achieve is to modify a message on the fly with a set of fields that are supplied to the program at runtime. simple case: // message declared as - const google::protobuf::Message& message auto x = reflection->GetDouble(message, field); // do some modification to x reflection->SetDouble(message, field, x); my main question is how in the world do I get from a const ref (needed for GetDouble() ) to a pointer (needed for SetDouble() )??? I know that if I knew the field name at compile time I would be able to use mutable_, but since I don't know that until runtime there does not seem to be an easy way to do this. Or I am just missing something super simple. Thanks, -- You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. To unsubscribe from this group and stop receiving emails from it, send an email to protobuf+unsubscr...@googlegroups.com. To post to this group, send email to protobuf@googlegroups.com. Visit this group at http://groups.google.com/group/protobuf. For more options, visit https://groups.google.com/d/optout.
