Add mechanism to specify that a parameter must be set?

[ceball]

Is it possible to make a Parameter that has to be set? I.e. if not specified on instance creation, an exception will be raised?

[ceball]

Not currently supported directly. You could approximate it by making the default value be None and adding an explicit test to the object's constructor to raise an exception if the value is still None after the super()'s constructor is called.

[MarcSkovMadsen]

Ahh. I'm currently very much hit by this lack of functionality in my daily work. See https://discourse.holoviz.org/t/how-to-make-parameter-values-mandatory/5124. I had forgotten about this issue. I can also see I've requested this functionality before in
#574

@philippjfr suggested on Discourse to add a required argument to Parameter.