Basic ITEM_LIST_REF help

[dwilbourn618]

I have been trying to add some ITEM_LIST_REFs to a menu but I can't get the syntax right. The only example I can find for the ITEM_LIST_REF just prints the color to the serial port using the callback
[](const Ref<uint8_t> color) { Serial.println(colors[color.value]);}
but I don't need to do that, assuming we use the same example, I just want to set a variable to the selected color name. : e.g. "Red" or "Green". I have been trying all day to work out what the correct syntax for this would be but without sucess.

[forntoh]

Can you please explain what you want to do tho the value later? Or better still provide a code snippet.

[dwilbourn618]

I just want to assign the selected color (in this example) to a string variable. That would be used as part of my program's preferences.
I know it's just me not understanding what is going on - I am really a Delphi programmer and this is my first foray into C++ so it's all new concepts and a whole different way of looking at code!

[forntoh]

When using ITEM_LIST_REF, the value you set from the menu is available for the whole program to use, you don't necessarily need the callback unless you want to execute something.

Just try setting the variable in the loop:

String myVar = "";

void loop() {
    ....
    // myColorIndex is the index passed into ITEM_LIST_REF, it will contain an up-to-date value of the selected value
    if (myVar.equals(colors[myColorIndex])) {
        myVar = String(colors[myColorIndex]);
    }
}

[dwilbourn618]

Sorry for being so dumb but I still don't understand. If I take your example code:

uint8_t selectedColor = 0;
std::vector<const char*> colors = {"Red", "Green", "Blue"};
MENU_SCREEN(mainScreen, mainItems,
    ITEM_LIST_REF("Color", colors, [](const Ref<uint8_t> color) {
        Serial.println(colors[color.value]);
    }, selectedColor)
);

and remove the callback stuff because I don't want it to print to the serial port when I change color

MENU_SCREEN(mainScreen, mainItems,
    ITEM_LIST_REF("Color", colors, , selectedColor)
);

Then the code does not compile. Presumably ther has to be something in the 3rd parameter? But what? I can't find any examples of what I might put there.
but I presume that once that is sorted, I would use

    if (myVar.equals(colors[selectedColor])) {
        myVar = String(colors[selectedColor]);

[forntoh]

MENU_SCREEN(mainScreen, mainItems,
    ITEM_LIST_REF("Color", colors, nullptr, selectedColor)
);

[dwilbourn618]

Sorry for the delay, I actually got round to testing your solution and that does not work either. I triednullptr, NULL and {NULL}but all fail to compile.