I have a question about traits in Scala. I have a trait returns a type of object (AA or BB) depending on the value of parameter country. My implemen ...

I have this error when I run my code using Backtrader library: **File "/Users/giovannicaridi/opt/anaconda3/lib/python3.7/site-packages/backtrader/fee ...

I have to construct and populate a supertype-subtype relationship, but I cannot get it to work the way it is supposed to be. Basically PERSON table is ...

I am looking at someone code and it uses <: when creating a struct. I looked in the docs and found out that this means they are creating an abstrac ...

I need to create an array-based stack that gets the method from an interface. There I want to implement the push(E e) method from the interface, but I ...

The following script comes from https://www.doctrine-project.org/projects/doctrine-orm/en/2.6/reference/inheritance-mapping.html#mapped-superclasses, ...

I am working with an overlap super/subtype relationship dealing with person(s) in my DB. What I would like to do is have the overlapping subtypes inse ...

Given the following example, why am I able to override the return type List<? extends IConfigUser> as List<ConfigUser> in getUserList() bu ...

In my code, I have a SuperType which has two SubTypes ... now I have a std::vector<SubTypeA>& and need to pass this to a function which iter ...

I am start using Lucidchart for designing erd for my assignments. I prefered lucidchart for its simplicity. But my diagram has an extended relationshi ...

I am most interested in the applicability to SBCL, but am curious about other implementations of Common Lisp as well. In Common Lisp we have the type ...

today in Theory of Programming Language class we have seen this behaviour in Java: In Main: Where the "incredible" is that the method must choos ...

Suppose any one designing the Database(ER model) and he have three tables CHECKING-ACCOUNT, SAVINGS-ACCOUNT, and LOAN-ACCOUNT. Tables. Suppose he is ...

I'm about to develop a personal project for learning purpose. A real-estate web site, where advertisers (registered users) can publish ads for their p ...

I'm trying to figure out how to (if it's even possible) change the base return type, when the type has yet to be passed to an abstract class. (I'm sor ...

This question piggybacks off of Foreign Key to multiple tables but I thought that my elaboration could use its own subject. Say I have the following ...

Why is it that even if you have declared a private static final variable, a color - defaultC, let's say - then you still cannot use this.defaultC in t ...

I have a type lecturer_typ with 2 sub types module_leader_typ and external_typ. I have inserted objects of all 3 of these types in one table called l ...

Im having trouble with this book class extending from a publication abstract class which extends from a publishable interface class. however when i tr ...

In a relational supertype/subtype structure where, for example, I have a supertype table entity with an entity_type column and a number of subtype tab ...