Create a new module

// Package mybase implements a base that only supports SetPower (basic forward/back/turn controls), IsMoving (check if in motion), and Stop (stop all motion).
// It extends the built-in resource subtype Base and implements methods to handle resource construction, attribute configuration, and reconfiguration.

package mybase

import (
    "context"
    "fmt"
    "math"

    "github.com/golang/geo/r3"
    "github.com/pkg/errors"
    "go.uber.org/multierr"

    "go.viam.com/rdk/components/base"
    "go.viam.com/rdk/components/base/kinematicbase"
    "go.viam.com/rdk/components/motor"
    "go.viam.com/rdk/logging"
    "go.viam.com/rdk/resource"
    "go.viam.com/rdk/spatialmath"
)

// Here is where we define your new model's colon-delimited-triplet (acme:my-custom-base-repo:mybase)
// acme = namespace, my-custom-base-repo = repo-name, mybase = model name.
var (
    Model            = resource.NewModel("acme", "my-custom-base-repo", "mybase")
    errUnimplemented = errors.New("unimplemented")
)

const (
    myBaseWidthMm        = 500.0 // Base has a wheel tread of 500 millimeters
    myBaseTurningRadiusM = 0.3   // Base turns around a circle of radius .3 meters
)

func init() {
    resource.RegisterComponent(base.API, Model, resource.Registration[base.Base, *Config]{
        Constructor: newBase,
    })
}

func newBase(ctx context.Context, deps resource.Dependencies, conf resource.Config, logger logging.Logger) (base.Base, error) {
    b := &myBase{
        Named:  conf.ResourceName().AsNamed(),
        logger: logger,
    }
    if err := b.Reconfigure(ctx, deps, conf); err != nil {
        return nil, err
    }
    return b, nil
}


// Reconfigure reconfigures with new settings.
func (b *myBase) Reconfigure(ctx context.Context, deps resource.Dependencies, conf resource.Config) error {
    b.left = nil
    b.right = nil

    // This takes the generic resource.Config passed down from the parent and converts it to the
    // model-specific (aka "native") Config structure defined, above making it easier to directly access attributes.
    baseConfig, err := resource.NativeConfig[*Config](conf)
    if err != nil {
        return err
    }

    b.left, err = motor.FromDependencies(deps, baseConfig.LeftMotor)
    if err != nil {
        return errors.Wrapf(err, "unable to get motor %v for mybase", baseConfig.LeftMotor)
    }

    b.right, err = motor.FromDependencies(deps, baseConfig.RightMotor)
    if err != nil {
        return errors.Wrapf(err, "unable to get motor %v for mybase", baseConfig.RightMotor)
    }

    geometries, err := kinematicbase.CollisionGeometry(conf.Frame)
    if err != nil {
        b.logger.CWarnf(ctx, "base %v %s", b.Name(), err.Error())
    }
    b.geometries = geometries

    // Stop motors when reconfiguring.
    return multierr.Combine(b.left.Stop(context.Background(), nil), b.right.Stop(context.Background(), nil))
}

// DoCommand simply echos whatever was sent.
func (b *myBase) DoCommand(ctx context.Context, cmd map[string]interface{}) (map[string]interface{}, error) {
    return cmd, nil
}

// Config contains two component (motor) names.
type Config struct {
    LeftMotor  string `json:"motorL"`
    RightMotor string `json:"motorR"`
}

// Validate validates the config and returns implicit dependencies,
// this Validate checks if the left and right motors exist for the module's base model.
func (cfg *Config) Validate(path string) ([]string, error) {
    // check if the attribute fields for the right and left motors are non-empty
    // this makes them required for the model to successfully build
    if cfg.LeftMotor == "" {
        return nil, fmt.Errorf(`expected "motorL" attribute for mybase %q`, path)
    }
    if cfg.RightMotor == "" {
        return nil, fmt.Errorf(`expected "motorR" attribute for mybase %q`, path)
    }

    // Return the left and right motor names so that `newBase` can access them as dependencies.
    return []string{cfg.LeftMotor, cfg.RightMotor}, nil
}

type myBase struct {
    resource.Named
    left       motor.Motor
    right      motor.Motor
    logger     logging.Logger
    geometries []spatialmath.Geometry
}

// MoveStraight does nothing.
func (b *myBase) MoveStraight(ctx context.Context, distanceMm int, mmPerSec float64, extra map[string]interface{}) error {
    return errUnimplemented
}

// Spin does nothing.
func (b *myBase) Spin(ctx context.Context, angleDeg, degsPerSec float64, extra map[string]interface{}) error {
    return errUnimplemented
}

// SetVelocity does nothing.
func (b *myBase) SetVelocity(ctx context.Context, linear, angular r3.Vector, extra map[string]interface{}) error {
    return errUnimplemented
}

// SetPower computes relative power between the wheels and sets power for both motors.
func (b *myBase) SetPower(ctx context.Context, linear, angular r3.Vector, extra map[string]interface{}) error {
    b.logger.CDebugf(ctx, "SetPower Linear: %.2f Angular: %.2f", linear.Y, angular.Z)
    if math.Abs(linear.Y) < 0.01 && math.Abs(angular.Z) < 0.01 {
        return b.Stop(ctx, extra)
    }
    sum := math.Abs(linear.Y) + math.Abs(angular.Z)
    err1 := b.left.SetPower(ctx, (linear.Y-angular.Z)/sum, extra)
    err2 := b.right.SetPower(ctx, (linear.Y+angular.Z)/sum, extra)
    return multierr.Combine(err1, err2)
}

// Stop halts motion.
func (b *myBase) Stop(ctx context.Context, extra map[string]interface{}) error {
    b.logger.CDebug(ctx, "Stop")
    err1 := b.left.Stop(ctx, extra)
    err2 := b.right.Stop(ctx, extra)
    return multierr.Combine(err1, err2)
}

// IsMoving returns true if either motor is active.
func (b *myBase) IsMoving(ctx context.Context) (bool, error) {
    for _, m := range []motor.Motor{b.left, b.right} {
        isMoving, _, err := m.IsPowered(ctx, nil)
        if err != nil {
            return false, err
        }
        if isMoving {
            return true, err
        }
    }
    return false, nil
}

// Properties returns details about the physics of the base.
func (b *myBase) Properties(ctx context.Context, extra map[string]interface{}) (base.Properties, error) {
    return base.Properties{
        TurningRadiusMeters: myBaseTurningRadiusM,
        WidthMeters:         myBaseWidthMm * 0.001, // converting millimeters to meters
    }, nil
}

// Geometries returns physical dimensions.
func (b *myBase) Geometries(ctx context.Context, extra map[string]interface{}) ([]spatialmath.Geometry, error) {
    return b.geometries, nil
}

// Close stops motion during shutdown.
func (b *myBase) Close(ctx context.Context) error {
    return b.Stop(ctx, nil)
}

#pragma once

#include <viam/sdk/components/base/base.hpp>
#include <viam/sdk/components/component.hpp>
#include <viam/sdk/components/motor/motor.hpp>
#include <viam/sdk/config/resource.hpp>
#include <viam/sdk/resource/resource.hpp>

using namespace viam::sdk;

// `MyBase` inherits from the `Base` class defined in the Viam C++ SDK and
// implements some of the relevant methods along with `reconfigure`. It also
// specifies a static `validate` method that checks configuration validity.
class MyBase : public Base {
   public:
    MyBase(Dependencies deps, ResourceConfig cfg) : Base(cfg.name()) {
        this->reconfigure(deps, cfg);
    };
    void reconfigure(Dependencies deps, ResourceConfig cfg) override;
    static std::vector<std::string> validate(ResourceConfig cfg);

    bool is_moving() override;
    void stop(const AttributeMap& extra) override;
    void set_power(const Vector3& linear,
                   const Vector3& angular,
                   const AttributeMap& extra) override;

    AttributeMap do_command(const AttributeMap& command) override;
    std::vector<GeometryConfig> get_geometries(const AttributeMap& extra) override;
    Base::properties get_properties(const AttributeMap& extra) override;

    void move_straight(int64_t distance_mm, double mm_per_sec, const AttributeMap& extra) override {
        throw std::runtime_error("move_straight unimplemented");
    }
    void spin(double angle_deg, double degs_per_sec, const AttributeMap& extra) override {
        throw std::runtime_error("spin unimplemented");
    }
    void set_velocity(const Vector3& linear,
                      const Vector3& angular,
                      const AttributeMap& extra) override {
        throw std::runtime_error("set_velocity unimplemented");
    }

   private:
    std::shared_ptr<Motor> left_;
    std::shared_ptr<Motor> right_;
};

#include "my_base.hpp"

#include <exception>
#include <fstream>
#include <iostream>
#include <sstream>

#include <grpcpp/support/status.h>

#include <viam/sdk/components/base/base.hpp>
#include <viam/sdk/components/component.hpp>
#include <viam/sdk/config/resource.hpp>
#include <viam/sdk/resource/resource.hpp>

using namespace viam::sdk;

std::string find_motor(ResourceConfig cfg, std::string motor_name) {
    auto base_name = cfg.name();
    auto motor = cfg.attributes()->find(motor_name);
    if (motor == cfg.attributes()->end()) {
        std::ostringstream buffer;
        buffer << base_name << ": Required parameter `" << motor_name
               << "` not found in configuration";
        throw std::invalid_argument(buffer.str());
    }
    const auto* const motor_string = motor->second->get<std::string>();
    if (!motor_string || motor_string->empty()) {
        std::ostringstream buffer;
        buffer << base_name << ": Required non-empty string parameter `" << motor_name
               << "` is either not a string "
                  "or is an empty string";
        throw std::invalid_argument(buffer.str());
    }
    return *motor_string;
}

void MyBase::reconfigure(Dependencies deps, ResourceConfig cfg) {
    // Downcast `left` and `right` dependencies to motors.
    auto left = find_motor(cfg, "left");
    auto right = find_motor(cfg, "right");
    for (const auto& kv : deps) {
        if (kv.first.short_name() == left) {
            left_ = std::dynamic_pointer_cast<Motor>(kv.second);
        }
        if (kv.first.short_name() == right) {
            right_ = std::dynamic_pointer_cast<Motor>(kv.second);
        }
    }
}

std::vector<std::string> MyBase::validate(ResourceConfig cfg) {
    // Custom validation can be done by specifying a validate function at the
    // time of resource registration (see main.cpp) like this one.
    // Validate functions can `throw` exceptions that will be returned to the
    // parent through gRPC. Validate functions can also return a vector of
    // strings representing the implicit dependencies of the resource.
    //
    // Here, we return the names of the "left" and "right" motors as found in
    // the attributes as implicit dependencies of the base.
    return {find_motor(cfg, "left"), find_motor(cfg, "right")};
}

bool MyBase::is_moving() {
    return left_->is_moving() || right_->is_moving();
}

void MyBase::stop(const AttributeMap& extra) {
    std::string err_message;
    bool throw_err = false;

    // make sure we try to stop both motors, even if the first fails.
    try {
        left_->stop(extra);
    } catch (const std::exception& err) {
        throw_err = true;
        err_message = err.what();
    }

    try {
        right_->stop(extra);
    } catch (const std::exception& err) {
        throw_err = true;
        err_message = err.what();
    }

    // if we received an err from either motor, throw it.
    if (throw_err) {
        throw std::runtime_error(err_message);
    }
}

void MyBase::set_power(const Vector3& linear, const Vector3& angular, const AttributeMap& extra) {
    // Stop the base if absolute value of linear and angular velocity is less
    // than 0.01.
    if (abs(linear.y()) < 0.01 && abs(angular.z()) < 0.01) {
        stop(extra);  // ignore returned status code from stop
        return;
    }

    // Use linear and angular velocity to calculate percentage of max power to
    // pass to set_power for left & right motors
    auto sum = abs(linear.y()) + abs(angular.z());
    left_->set_power(((linear.y() - angular.z()) / sum), extra);
    right_->set_power(((linear.y() + angular.z()) / sum), extra);
}

AttributeMap MyBase::do_command(const AttributeMap& command) {
    std::cout << "Received DoCommand request for MyBase " << Resource::name() << std::endl;
    return command;
}

std::vector<GeometryConfig> MyBase::get_geometries(const AttributeMap& extra) {
    auto left_geometries = left_->get_geometries(extra);
    auto right_geometries = right_->get_geometries(extra);
    std::vector<GeometryConfig> geometries(left_geometries);
    geometries.insert(geometries.end(), right_geometries.begin(), right_geometries.end());
    return geometries;
}

Base::properties MyBase::get_properties(const AttributeMap& extra) {
    // Return fake properties.
    return {2, 4, 8};
}

// Package main is a module which serves the mybase custom model.
package main

import (
    "context"

    "go.viam.com/rdk/components/base"
    "go.viam.com/rdk/logging"
    "go.viam.com/rdk/module"
    "go.viam.com/utils"

    // Import your local package "mybase"
    // NOTE: Update this path if your custom resource is in a different location,
    // or has a different name:
    "go.viam.com/rdk/examples/customresources/models/mybase"
)

func main() {
    // NewLoggerFromArgs will create a logging.Logger at "DebugLevel" if
    // "--log-level=debug" is an argument in os.Args and at "InfoLevel" otherwise.
    utils.ContextualMain(mainWithArgs, module.NewLoggerFromArgs("mybase"))
}

func mainWithArgs(ctx context.Context, args []string, logger logging.Logger) (err error) {
    myMod, err := module.NewModuleFromArgs(ctx, logger)
    if err != nil {
        return err
    }

    // Models and APIs add helpers to the registry during their init().
    // They can then be added to the module here.
    err = myMod.AddModelFromRegistry(ctx, base.API, mybase.Model)
    if err != nil {
        return err
    }

    err = myMod.Start(ctx)
    defer myMod.Close(ctx)
    if err != nil {
        return err
    }
    <-ctx.Done()
    return nil
}

#include <memory>
#include <signal.h>

#include <boost/log/trivial.hpp>
#include <grpcpp/grpcpp.h>
#include <grpcpp/server_context.h>

#include <viam/api/common/v1/common.grpc.pb.h>
#include <viam/api/component/generic/v1/generic.grpc.pb.h>
#include <viam/api/robot/v1/robot.pb.h>

#include <viam/sdk/components/base/base.hpp>
#include <viam/sdk/components/component.hpp>
#include <viam/sdk/config/resource.hpp>
#include <viam/sdk/module/module.hpp>
#include <viam/sdk/module/service.hpp>
#include <viam/sdk/registry/registry.hpp>
#include <viam/sdk/resource/resource.hpp>
#include <viam/sdk/rpc/dial.hpp>
#include <viam/sdk/rpc/server.hpp>

#include "my_base.hpp"

using namespace viam::sdk;

int main(int argc, char** argv) {
    API base_api = Base::static_api();
    Model mybase_model("acme", "my-custom-base-repo", "mybase");

    std::shared_ptr<ModelRegistration> mybase_mr = std::make_shared<ModelRegistration>(
        base_api,
        mybase_model,
        [](Dependencies deps, ResourceConfig cfg) { return std::make_unique<MyBase>(deps, cfg); },
        MyBase::validate);

    std::vector<std::shared_ptr<ModelRegistration>> mrs = {mybase_mr};
    auto my_mod = std::make_shared<ModuleService>(argc, argv, mrs);
    my_mod->serve();

    return EXIT_SUCCESS;
};