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Unread 11-01-2017, 17:09
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euhlmann euhlmann is offline
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Re: SendableChooser changes and errors

Quote:
Originally Posted by bob.wolff68 View Post
It appears that SendableChooser is now a template based class. Is there any documentation on how to use it?

We made some changes to use it as:
Code:
SendableChooser<int> *pChoice;
pChoice = new SendableChooser<int>();
And once instantiated and objects are added, wanted to check it via:
Code:
int ch = pChoice->GetSelected();
or
Code:
int ch = (int)pChoice->GetSelected();
Both have been unsuccessful. Errors from compilation are:
Code:
arm-frc-linux-gnueabi-g++ -std=c++1y -I/Users/rwolff/wpilib/cpp/current/include -I/Users/rwolff/dev/robotics/FRCTeam1967/code/NatSndChTestJig/src -I/Users/rwolff/dev/robotics/FRCTeam1967/code/include -I/Users/rwolff/wpilib/user/cpp/include -O0 -g3 -Wall -c -fmessage-length=0 -o src/Robot.o ../src/Robot.cpp 
In file included from /Users/rwolff/wpilib/cpp/current/include/SmartDashboard/SendableChooser.h:51:0,
                 from /Users/rwolff/wpilib/cpp/current/include/WPILib.h:72,
                 from ../src/Robot.cpp:1:
/Users/rwolff/wpilib/cpp/current/include/SmartDashboard/SendableChooser.inc: In instantiation of 'T frc::SendableChooser<T>::GetSelected() [with T = int]':
../src/Robot.cpp:38:42:   required from here
/Users/rwolff/wpilib/cpp/current/include/SmartDashboard/SendableChooser.inc:60:12: error: cannot convert 'std::nullptr_t' to 'int' in return
     return nullptr;
            ^
/Users/rwolff/wpilib/cpp/current/include/SmartDashboard/SendableChooser.inc: In member function 'T frc::SendableChooser<T>::GetSelected() [with T = int]':
I'm not sure if maybe it's only intended to be used with classes or class pointers and not something simple like an int possibly? Or if there's something more basic in err here.

Thanks!
roboBob
nullptr is std::nullptr_t while you set the return type to int. Make it return the correct type. You can use specialized template functions
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Last edited by euhlmann : 11-01-2017 at 17:11.
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