Keep in mind, I'm talking about beginners here. Beginner kids, even (it's a popular language for Roblox scripting!).
Are either of those things, things that will just come naturally to newbies? Are they definitely gonna know about them when they pick up the language in random text or video tutorials? Are they going to remember to use local as often as they can, and will they understand when it's appropriate to use a global?
The answer to all of these is no, obviously. For someone like me with a CS degree and several years of professional experience, your suggestions are perfectly reasonable, but in the wide, wacky world of beginners hacking things together, the right way should be easy and obvious. So obvious, even a beginner will catch on.
> Copying a table is generally unnecessary, if you never mutate the table to be cloned. Just set the __index property of a new table to a reference to the table to be cloned. Ta-da, you have inherited the previous table.
How is this more intuitive than just having a copy or clone function? You can find plenty of cloning functions on stackoverflow or wherever that people have written. Yes, there are workarounds, but why do you need a workaround for a pretty basic use case here? In python, you can just go "dict2 = dict(dict1)", or "dict2 = dict1.copy()", both of those are easy enough, and more importantly, they're intuitive: want a copy? Call the copy function! Why does Lua have to make it weird?
> This is one of those times where power users are given the advantage at the cost of the less experienced, and I share your implied concern in feeling the inconsistencies in who is favored by which language features.
Yes, it seems like the language design is a strange mix of "really easy to get started for beginners" and "footguns that you probably need to be experienced to avoid".
I think the argument is more that Roblox should be setting up its Lua environment that way.
> In python, you can just go "dict2 = dict(dict1)", or "dict2 = dict1.copy()", both of those are easy enough, and more importantly, they're intuitive: want a copy? Call the copy function!
A shallow copy, which can be very surprising. And since Lua has metatables and userdata, it's impossible to write a deep copy that works correctly in all circumstances.
There's no language I really truly love, but the one I find myself recommending as a result of good tradeoffs between simplicity and usability is Python.
My guess for why Lua doesn't provide a table copy function is because then they'd have to decide whether to provide shallow or deep copies, and deep copies have to do cycle detection and other such stuff. Then there's metatables, functions, and so on.
This is just another one of those situations where Lua is not catering to anyone by randomly catering to one group or another. No one is happy.
With regards to variables, the best way to hack around this issue is to 1) always use `local` when declaring a variable and 2) set `_G`'s metatable to raise an error if you try to create a new key, which prevents accidentally using globals like you've inadvertently discovered is the default behavior. This is this way because it is I guess simpler than teaching someone how declarations work, but it obviously leads to a pretty immediately bad situation for anyone who wants to do more programming than setting a global constant. It harkens back from when Lua was basically a TCL-like.
Copying a table is generally unnecessary, if you never mutate the table to be cloned. Just set the __index metatable property of a new table to a reference to the table to be cloned. Ta-da, you have inherited the previous table. Not giving you an immediate, easy way to do this forces you to come to terms with copying not always being the right solution. It's not great, and the language offers no pointers to those who want to get a thing done, but it isn't the worst choice.
Not providing increment operators is a design choice, one that simplifies the metatabling for operators. Only having one case for addition, and not having to worry about increment / incremental assignment, means people creating metatables that override operators have a good experience. This is one of those times where power users are given the advantage at the cost of the less experienced, and I share your implied concern in feeling the inconsistencies in who is favored by which language features.