Safer - Paranoid Lua programming

Taking defensive programming to the next level. Use this module to avoid unexpected globals creeping up in your code, and stopping sub-modules from fiddling with fields of tables as you pass them around.

API

safer.globals([exception_globals], [exception_nils])

No new globals after this point.

exception_globals is an optional set (keys are strings, values are true) specifying names to be exceptionally accepted as new globals. Use this in case you have to declare a legacy module that declares a global, for example. A few legacy modules are already handled by default.

exception_nils is an optional set (keys are strings, values are true) specifying names to be exceptionally accepted to be accessed as nonexisting globals. Use this in case code does feature-testing based on checking the presence of globals. A few common feature-test nils such as jit and unpack are already handled by default.

t = safer.table(t)

Block creation of new fields in this table.

Note that this is implemented creating a proxy table, so:

• Equality tests will fail: safer.table(t) ~= t
• If anyone still has a reference to this table prior to creating the safer version, they can still mess with the unsafe table and affect the safe one.

t = safer.readonly(t)

Make table read-only: block creation of new fields in this table and setting new values to existing fields.

Note that this is implemented creating a proxy table, so:

• Equality tests will fail: safer.readonly(t) ~= t
• If anyone still has a reference to this table prior to creating the safer version, they can still mess with the unsafe table and affect the safe one.

About

This module was created by Hisham Muhammad - @hisham_hm

Licensed under the terms of the MIT License, the same as Lua.

During its genesis, this module was called "safe", but I renamed it to "safer" to remind us that we are never fully safe. ;)