How can I set a property for the upper limit for another property's range

Question

I have two properties, I would like to set one property as the upper limit of another property, hence making the upper rely on a property. As below:

public int fullLength;

[Range(0, fullLength)]
public int segmentLength;

Is there a way to do this, possibly with a custom editor? If yes, how can it be done?

Answer 1

It's pretty simple, use OnValidate():

public int fullLength;
public int segmentLength;

private void OnValidate() {
    if (segmentLength < 0) segmentLength = 0;
    else if (segmentLength > fullLength) segmentLength = fullLength;
}

This method is called (in editor only) whenever the script is loaded or a value is changed in the Inspector.

P.S.: You're not using properties here, you're using fields.