How I can add prototype to string

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1

I tried that:

string.startswith = function(self, str) 
	return self:find('^' .. str) ~= nil
end

local ss1 = "hello my name is ..."
print(ss1:startswith('hello'))

Error: Attempt to modify a readonly table

so how can i do it?

2

i think the issue is the first line. You are trying to allocate a new function the string, which is not possible. Try replacing the first string with another name (even String would work, it just cant be the exact same)

3

What about:

local _string = string -- Preserve old string library

local string = {}
setmetatable(string, {__index = _string}) -- Make references to original string library

function string.startsWith(...)
    ...
end

Keep in mind you will have to put this in every script and you probably can’t do it from a module script. (You can store the other functions sure, but to replace string you will have to put that code in your script directly.)

4

Error: attempt to call a nil value on line 10

code:

local _string = string -- Preserve old string library
local string = {}
setmetatable(string, {__index = _string}) -- Make references to original string library

function string.startsWith(...)
print(...)
end

local ss1 = "hello my name is ..."
print(ss1:startsWith("hello")) -- line 10
5

Warning: Unknown global 'String’

6

Ah, well you will have to use string.startsWith in that case. You cannot call a function on a string literal directly because that will reference the original string library.

7 
String = {}
String.startswith = function(self, str) 
	return self:find('^' .. str) ~= nil
end

local ss1 = "hello my name is ..."
print(String.startswith(ss1, 'hello'))
1 Like
8

but I want prototype like:

ss1:startsWith("hello")
9

as far as I can tell, that wouldn’t be possible. Using the String.startswith() would be the only option

1 Like