Feature Request: Add constant annotation to show a warning when modifying variables marked as const

[sniper00]

Constant modifications can be detected in the editor in advance.

example:

---@const_type  ErrorCode
local errorCode = {}

errorCode.NOT_FOUND = 10 --- show warnings attemp modify constant variables.

[Mayron]

I love the idea, but I would suggest using ---@const for the variable itself to show that the variable cannot be reassigned, and if you want values within a data structure to be constants then use something like ---@readonly or ReadOnly data types.

local tbl = {}; ---@const table<string, string>

tbl = 123 -- this should not be allowed!

tbl.hello = "hi" -- this is fine

and for making the hello field also a constant:

local tbl = {} ---@const ReadOnly<table<string, string>>
tbl.hello = "hi" -- not allowed!

Or readonly for @field and @param annotations:

---@param readonly msg string
local function Print(msg)
  msg = "something else" -- not allowed!
end 

---@class Program
---@field readonly ProcessID number

[sniper00]

I love the idea, but I would suggest using ---@const for the variable itself to show that the variable cannot be reassigned, and if you want values within a data structure to be constants then use something like ---@readonly or ReadOnly data types.

local tbl = {}; ---@const table<string, string>

tbl = 123 -- this should not be allowed!

tbl.hello = "hi" -- this is fine

and for making the hello field also a constant:

local tbl = {} ---@const ReadOnly<table<string, string>>
tbl.hello = "hi" -- not allowed!

Or readonly for @field and @param annotations:

---@param readonly msg string
local function Print(msg)
  msg = "something else" -- not allowed!
end 

---@class Program
---@field readonly ProcessID number

Yes， readonly is indeed more appropriate.

[jordan4ibanez]

This would be ultra extremely helpful. Perhaps lump together the four. immutable constant final readOnly. In lua's case, these all have the same effect.

[curiosity-a]

I desperately need a way to mark mutability/ownership of function parameters and return values. A feature like this might help.