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Source

• Introduction

Module Lock

Protects tables against accidential read/write.

Module Status: Experimental 2020-10-31.

Usage:

local Lock = require('__eradicators-library__/erlib/lua/Lock')()

Functions

auto_lock(tbl, name[, passphrase[, err_write[, err_read]]])	Prevents accidential writing to tables.
is_locked(tbl)	Detects if a table was locked by this module.
remove_lock(tbl)	Removes any locks created by this module.

Functions

auto_lock(tbl, name[, passphrase[, err_write[, err_read]]])

Prevents accidential writing to tables. Intended mainly to detect leaking global access when you forgot to type "local" again. It is called "Auto"-Lock because it re-locks any key as soon as it becomes nil, even if it had a value before.

Note: You have to manually remove this after your done if you use it in any of the shared loading stages (data, settings).

Parameters:

• tbl table The table to apply the lock to.
• name string The table's name. Used for error messages.
• passphrase string → usage examples are below. (optional)
• err_write function A custom error handler. f(tbl,key,value) (optional)
• err_read function A custom error handler. f(tbl,key) (optional)

Returns:

table The now locked table tbl.

Usage:

-- Apply the lock to any table.
-- For this example we'll apply it to the global environment.
Lock.auto_lock(_ENV,'Global Environment','MyPassword')

-- Accidential writing of ney keys will fail.
_ENV.A_New_Key = 'A new value!'
> Error! Global Environment is write locked!

-- Accidential read will also fail.
if _ENV.A_New_Key then print('not ok') end
> Error! Global Environment is read locked!

-- Use __has_key instead.
if not _ENV.__has_key('A_New_Key') then print('ok') end
> ok

-- The passphrase function allows you to explicitly circumvent the lock.
MyPassword('A_New_Key','A new value!')
print(_ENV.A_New_Key)
> A new value!

-- Keys that become nil will become locked again.
_ENV.A_New_Key = nil
if _ENV.A_New_Key then print('not ok') end
> Error! Global Environment is read locked!

-- You can declare a key global without assigning a value.
MyPassword('Another_New_Key')
if not Another_New_Key then print('ok this time!') end
> ok this time!

-- It'll have the default value of boolean false.
if (Another_New_Key == false) then print('I got it.') end
> I got it.

is_locked(tbl)

Detects if a table was locked by this module.

Parameters:

• tbl table

Returns:

boolean

remove_lock(tbl)

Removes any locks created by this module. Will error if you try to remove any other kind of lock or metatable.

Parameters:

• tbl table