[SURVEY] There's A Really Really Terrible Bug Where Child Blueprints Get Their Variables Reset

[anonymous_user_01d6d4b81 (anonymous_user_01d6d4b8)]

@anonymous_user_759e5c3a

Thanks for posting this over . Repros help a ton

@anonymous_user_799e2bc7

Hi,
Something I have seen several times with Blueprints inheriting from each others, is that by design Unreal doesn’t seem to store a flag to remember if a property has been overriden or not.
Which means it only relies on a diff with the parent BP to consider a property to be overriden or not (yellow arrow) and actually save the value.
The consequence is that I often see bugs similar to the ones described in this thread (inherited values being reset).

is an example :
1 - Have some BP named “base” with an integer property “health” set to 100.
2 - Have a BP named “child”, with “base” as a parent, and "health set to 50. A yellow arrow will appear to notify the value as overriden
3 - Take the “base”, modify the “health” value to 50, then back to 100. The “child” health will be updated to 100 too.
Whenever the base BP property is equal to the overriden child property, Unreal seems to consider that it is no more overriden.

I have seen this behaviour up to 4.16, haven’t tested on more recent builds.
I hope it will help !

It is called data inherit in programming.
Store a flag to indicate whether some child property should override parent property is not necessary, and make it a bit not clean.
Dictionary data struct is used to store the property’s name and value pair.
If the child object does not have a specific property in it’s dictionary, then it will inherit from the parent.
If the child object has a specific property in it’s dictionary, then it overrides the parent.