Apply two CustomAttributes on one member

Unity Engine
1

Hi everybody.

I made two useful Custom Attributes : Min and Max. They require one parameter, an int or a float, and respectively prevent a class member value to be less or more than the given parameter.

In my script, I can do this :

[SerializeField, Min(0.0f)]
private float m_TestValue = 0.0f;

[SerializeField, Max(2.0f)]
private float m_TestValue2 = 0.0f;

I can make a member Serialized AND use the Min or Max attribute.
But I can’t do this :

[SerializeField, Min(0.0f), Max(2.0f)]
private float m_TestValue3 = 0.0f;

Only the first CustomAttribute (Min, in this example) will be used. But with the Unity attributes I can use at the same time SerializeField and HideInInspector for a member.

Why I can’t use more than one Custom Attribute on a member ? And how I can make it possible ?

Thanks for your answers :wink:

2

I’m assuming Min and Max are custom attributes that are dealt with by PropertyDrawer.

You can only have ONE PropertyDrawer affiliated attribute on a field. And if the type of that field uses a PropertyDrawer, only one is used.

This is just the way that PropertyDrawers work.

SerializeField is not a PropertyDrawer attribute.
Nor is Tooltip, Header, and a few other unity specific attributes. And of course any .Net attributes aren’t either.

I did not like this myself, so I wrote my own custom editor to deal with this… but it is NOT trivial.

You can see it here:

Editor entry point:

That references around a lot to several classes to work correctly, and requires reflecting out a lot of internal classes from Unity themselves.

And even with it, there are ramifications to stacking PropertyDrawers… only drawers that logically work with one another can stack.

3

Oh, and of course… unity has a ‘Range’ attribute that does a ‘MinMax’ type thing.

[SerializeField, Range(0.0f, 2.0f)]
private float m_TestValue = 0.0f;
1 Like
4

I know the Range Attribute. Use both Min and Max is only for my example. But use them separately is better than a Range. If you make a Range(0.0f, Mathf.Infinity), you’ll have a useless slider.

Thanks for your answer, I’ll check your scripts later :wink: