Now that Meta properties are are getting love, defining them should be made easier.

[SilencedPerson]

#58608 introduced ability to return default value when meta property doesn't exits.
This makes meta properties much more useful especially as flag list or list of properties to be serialized and saved, I would now like to be able to define them with ease much like regular variables. Syntax could go like this:
meta name_of_meta_property = true

[Mickeon]

Properties do not function the same way as meta properties. They're not featured in the Class definition, they are not guaranteed to exist, and their behaviour is more akin to an intrinsic Dictionary every Object may come with. It's more worth it make that clear with pre-defined functions that manage them. They already can be defined with ease as is.

[SilencedPerson]

All objects come with meta which is really just an empty object hence why values can be defined at runtime, it's either empty or contains some properties. I do not really see much difference with user defined variables that can also undefined. On the other hand, In this pull request, meta properties can be accessed safely with get_meta_or_default(). Being able to define meta properties outside of a function is very worthwhile as it declutters functions like _ready() while also bringing the meta properties to forefront.

[Mickeon]

For all intents and purposes, if a variable is so important as to be needed to be defined outside of the _ready() method, it should just be a normal property. Splitting the concept can get confusing and brings little on the table for the average user.