# Error handling

Simplygon API reports errors through the error handling class ErrorHandler. A user can derive a class from ErrorHandler, which then will receive processing errors, and handle them appropriately. In C# and Python, if no error handler is set, the errors are reported through exception handling.

This example shows how to use the Simplygon error handler.

// Copyright (c) Microsoft Corporation. 
// Licensed under the MIT license. 

#include <string>
#include <stdlib.h>
#include <filesystem>
#include <future>
#include "SimplygonLoader.h"

class CustomErrorHandler : public Simplygon::ErrorHandler
{
	public:
	void HandleError(Simplygon::spObject object, const char* interfaceName, const char* methodName, Simplygon::rid errorType , const char* errorText) override
	{
		printf("Error (%s:%s): %s\n", interfaceName, methodName, errorText);
	}
} customErrorHandler;


void RunReduction(Simplygon::ISimplygon* sg)
{
	// Set the custom error handler to the Simplygon interface. 
	sg->SetErrorHandler(&customErrorHandler);

	// Create the reduction pipeline. 
	Simplygon::spReductionPipeline sgReductionPipeline = sg->CreateReductionPipeline();

	// To be able to use the T-Junction remover, the welder has to be enabled so this will trigger an 
	// error. 
	Simplygon::spRepairSettings sgRepairSettings = sgReductionPipeline->GetRepairSettings();

	sgRepairSettings->SetUseWelding( false );

	sgRepairSettings->SetUseTJunctionRemover( true );

	// Start the reduction pipeline and the faulty settings will cause an error. 
	sgReductionPipeline->RunSceneFromFile("../Assets/SimplygonMan/SimplygonMan.obj", "output.fbx", Simplygon::EPipelineRunMode::RunInNewProcess);

}

int main()
{
	Simplygon::ISimplygon* sg = NULL;
	Simplygon::EErrorCodes initval = Simplygon::Initialize( &sg );
	if( initval != Simplygon::EErrorCodes::NoError )
	{
		return int(initval);
	}

	RunReduction(sg);

	Simplygon::Deinitialize(sg);

	return 0;
}

// Copyright (c) Microsoft Corporation. 
// Licensed under the MIT license. 

using System;
using System.IO;
using System.Threading.Tasks;

public class CustomErrorHandler : Simplygon.ErrorHandler
{
    public override void HandleError(Simplygon.spObject obj, string interfaceName, string methodName, int errorType , string errorText)
    {
        Console.WriteLine($"Error ({interfaceName}:{methodName}): {errorText}");
    }
}

public class Program
{
    static private CustomErrorHandler customErrorHandler;

    static void RunReduction(Simplygon.ISimplygon sg)
    {
        // Set the custom error handler to the Simplygon interface. 
        sg.SetErrorHandler(customErrorHandler);
        // Create the reduction pipeline. 
        using (Simplygon.spReductionPipeline sgReductionPipeline = sg.CreateReductionPipeline())
        {
            // To be able to use the T-Junction remover, the welder has to be enabled so this will trigger an 
            // error. 
            using (Simplygon.spRepairSettings sgRepairSettings = sgReductionPipeline.GetRepairSettings())
            {
                sgRepairSettings.SetUseWelding( false );

                sgRepairSettings.SetUseTJunctionRemover( true );

            }
            // Start the reduction pipeline and the faulty settings will cause an error. 
            sgReductionPipeline.RunSceneFromFile("../Assets/SimplygonMan/SimplygonMan.obj", "output.fbx", Simplygon.EPipelineRunMode.RunInNewProcess);

        }
    }
    static int Main(string[] args)
    {
        using (var sg = Simplygon.Loader.InitSimplygon(out var errorCode, out var errorMessage))
        {
            if (errorCode != Simplygon.EErrorCodes.NoError)
                return (int)errorCode;
            customErrorHandler = new CustomErrorHandler();
            RunReduction(sg);
        }

        return 0;
    }
}

# Copyright (c) Microsoft Corporation. 
# Licensed under the MIT license. 

import math
import os
import sys
import glob
import gc
import threading

from pathlib import Path
from simplygon import simplygon_loader
from simplygon import Simplygon

class CustomErrorHandler(Simplygon.ErrorHandler):
    def HandleError(self, object: Simplygon.spObject, interfaceName: str, methodName: str, errorType: int, errorText: str):
        print('Error (%s:%s): %s' %(interfaceName, methodName, errorText))

customErrorHandler = CustomErrorHandler()

def RunReduction(sg: Simplygon.ISimplygon):
    # Set the custom error handler to the Simplygon interface. 
    sg.SetErrorHandler(customErrorHandler)
    # Create the reduction pipeline. 
    sgReductionPipeline = sg.CreateReductionPipeline()

    # To be able to use the T-Junction remover, the welder has to be enabled so this will trigger an 
    # error. 
    sgRepairSettings = sgReductionPipeline.GetRepairSettings()

    sgRepairSettings.SetUseWelding( False )

    sgRepairSettings.SetUseTJunctionRemover( True )

    # Start the reduction pipeline and the faulty settings will cause an error. 
    sgReductionPipeline.RunSceneFromFile("../Assets/SimplygonMan/SimplygonMan.obj", "output.fbx", Simplygon.EPipelineRunMode_RunInNewProcess)


if __name__ == '__main__':
    sg = simplygon_loader.init_simplygon()
    if sg is None:
        exit(Simplygon.GetLastInitializationError())

    RunReduction(sg)

    sg = None
    gc.collect()

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