Error: within this context
 

I'm trying to add the code for the Axis camera and I keep seeing this error when I build the project "error: within this context".

#include "WPILib.h"
#include "Gamepad.h"
#include "Vision/AxisCamera.h"

class RobotDemo : public SimpleRobot
{
RobotDrive myRobot; // robot drive system
Gamepad controller;
AxisCamera camera;

public:
RobotDemo(void):
myRobot(10, 9, 2, 1), // these must be initialized in the same order
controller(1)
{ <------ERROR HERE

All I did was add the AxisCamera header file and the identifier (AxisCamera camera).

What am I missing? Thanks.

Re: Error: within this context
 

You've added a data member called camera, of type AxisCamera, no problem there. But the code you've included has a constructor with an initialization list, and you haven't added a value for camera field.

Not being that familiar with the C++ WPI code, the issue is likely that the AxisCamera doesn't have a default constructor or for some other reason, the compiler wants camera to be assigned using the initialization list.

Try putting

camera(???)

after the controller(1) line and before the {. Replace ??? with the parameters required for an AxisCamera object to be initialized.

Gotta love compiler error messages sometimes.

Greg McKaskle

Re: Error: within this context
 

AxisCamera is a singleton. You shouldn't be calling the constructor directly. Try this.

Re: Error: within this context
 

Thanks for the reply. It looks like I have a different problem now. When I try to implement your suggestion and use:

I get an error that says "cannot convert 'AxisCamera' to 'AxisCamera*' in assignment". Can you explain what this means?

Thanks again.

Re: Error: within this context
 

You should declare the camera as:

Re: Error: within this context
 

Thanks for the correction mikets. I misread the header when I wrote my initial post. I updated it to have the reference declaration instead of a pointer.

Re: Error: within this context
 

I really appreciate both of your replies, but making the corrections you suggested has led me to another problem.

The first error says "uninitialized reference". How do I initialize it?
The second error gets me back to where I started. It says "error within this context".

This feels like one step forward then two steps back. Thanks for your help.

Re: Error: within this context
 

You need to initialize all non pointer members before the body (and especially references, they only have one life)

try this:Also, "error within this context" is part of a larger error, open the build console and find the red lines to find the rest of the message. many messages are 2 or more parts.
Ex (bold is error in code)
file.cpp: In constructor `ZomBDashboardPacketSender::ZomBDashboardPacketSen der()':
file.cpp:301: error: uninitialized reference member `ZomBDashboardPacketSender::hp'
WPILib/Dashboard.h:58: error: `void Dashboard::operator=(const Dashboard&)' is private
file.cpp:302: error: within this context