DFRobot Multigas String Usage

[SeamusTappert]

The DFRobot Multigas sensor header file includes the string library. We need to find all the areas where this is being used and replace it and then remove the string library entirely.

[RoryLGroom]

Loom_DFRobot String Removal

In the DFRobot_MultiGasSensor.h file, there are a couple functions which use and utilize strings.
The functions I have found so far are:

Inside queryGasType, which returns an Arduino string.

And in SetThreshholdAlarm, which takes an Arduino string as a parameter.

Arduino Strings and strings in general are not recommended for use because of its potential to fragment our limited memory.

The queryGasType function returns the name of the gas that is picked up. In the current multigas sensor code

void Loom_DFMultiGasSensor::measure() {
    FUNCTION_START;
    if(moduleInitialized ){
        if(checkDeviceConnection()){

            // Update the current gas type
            // currentGasType = gasSensor.queryGasTypeCstr();
            // if(strlen(currentGasType) <= 0){
            //     currentGasType = "INV_TYPE";
            // }

             cont...

The commented line should be updating the name variable in the Multigas class

        const char* currentGasType = "";
        float currentConcentration = 0.0f;
        float currentTemperature = 0.0f;

With the aforementioned function partially commented out, the currentGasType does not get set,

void Loom_DFMultiGasSensor::package() {
    FUNCTION_START;
    if(moduleInitialized){
        JsonObject json = manInst->get_data_object(getModuleName());
        json[currentGasType] = currentConcentration;
        json["Temp(C)"] = currentTemperature;

    }
    FUNCTION_END;
}

Here, we see that the value that should be used for our JSON index is the currentGasType, which should just be an empty string.
However, after discussion with the wisp team and seeing some of their values, it doesn't look like the package function is causing any issues for them as of yet.

Plan For Testing

The current plan will be to remove the string library from the multigas sensor code, and see how the wisp teams current implementation responds to that change. If the commented out lines of code arent causing issues, then we should be fine to simply remove the library.

[RoryLGroom]

Link to DFRobot_MultigasSensor.h: https://github.com/DFRobot/DFRobot_MultiGasSensor/blob/main/DFRobot_MultiGasSensor.h