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by JanisErdmanis 96 days ago
One can always look as global variables equivalent to a context object that’s is passed in every function. It’s just a syntactic difference whether one constructs such data structure or uses it implicitly via globals.

What I am getting at is that when one has such gigantic data structure there is no separation of concerns.

1 comments

Does one need one's separation of concerns if one's concerns shouldn't be separated in the in the first place?

Anytime one has access to a database one has access to one large global data structure that one can access from anywhere is a program.

This same concept goes for one's global state in one's game if one is making a game.

Separation of concerns is still a valid paradigm with a single global datastructure like GUI, Microservice, Database and etc. In such situation one can still seperate concerns via composing the global datastructure from a smaller units and define methods with respect to thoose smaller units. In that way one does not need to wonder whether there are some unattended side effects when calling a function that mutates the state.
Seems like one is backpedaling because one was just talking about one's separation of one's concerns and now one is defending one's separation of concerns with respect to one's global data structure.
I still firmly believe that one ctx object and hundred functions/methods is as bad as programming with plain variables defined in the global scope. If the ctx is composed from smaller data structures with whom the functions are defined, then all is good. This is the opposite of the rule.
But why?

You keep saying you believe it, but that is literally what a database is, game state manipulation, string manipulation, iterator algorithms, list comprehensions, range algorithms, image manipulations, etc. These are all instances where you use the same data structures over and over with as many algorithms and functions and you need.

It’s about coupling and being able to maintain that in the long term. A narrow focus helps to test each individual unit in isolation from each other. It is true that a database appears to be a single datastructure with hundreds of methods from the users perspective and that is fine, because someone else engineered and tested it for you. However if you were to look into how a database is implemented you would get to see the composition of data structures, like btrees that are tested in isolation.