How to assign motors mid-code?

Programming Support VEXcode Pro V5 Text Tech Support
#1

I am creating a program that requires me to assign ports to a motor, with the port numbers loaded from the SD card. It appears that I am unable to redeclare the motors mid-code. Any suggestions?

Example:
motor ArmMotor(PORT1, gearSetting::ratio36_1, false);

int main() {
ArmMotor = motor(PORT5, gearSetting::ratio36_1, false);
}

Result: Does not change motor connection from PORT1 to PORT5.

Thanks in advance.

#2

See this thread - it’s about doing something similar in PROS but is also applicable to VEXcode.

The gist is, rather than maintaining a bunch of motor objects, you maintain a bunch of pointers to motor objects. Then when you want to ‘change ports’ you initialize a new motor object on the new port and point the pointer at the new object rather than the old object.

#3

It doesn’t have to be that complicated. The code below works. It all depends if the motor object goes out of scope or not.

#include "vex.h"

using namespace vex;

// A global instance of vex::brain used for printing to the V5 brain screen
vex::brain       Brain;

// define your global instances of motors and other devices here
vex::motor       m1(PORT1, ratio18_1 );
vex::controller  c;

int main() {
    int count = 0;
   
    while(1) {
      if( c.ButtonA.pressing() ) {
        while( c.ButtonA.pressing() )
          this_thread::sleep_for(10);

        m1.stop();

        // swap to other motor
        if( m1.index() == PORT1 )
          m1 = vex::motor( PORT2, ratio18_1 );
        else
          m1 = vex::motor( PORT1, ratio18_1 );
      }

      if( c.ButtonX.pressing() ) {
        m1.spin(fwd);        
      }
      else {
        m1.stop();
      }

      Brain.Screen.printAt( 10, 50, "Motor index %d", m1.index() );
      Brain.Screen.printAt( 10, 70, "Motor speed %.2f", m1.velocity( rpm ) );
      // Allow other tasks to run
      this_thread::sleep_for(10);
    }
}
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