loadFile

Loadfile is a function in the standard Lua libraries that reads a Lua source file, compiles it as a chunk, and returns the compiled chunk as a function. It does not execute the chunk by itself; instead, it provides a callable representation of the code that can be invoked later, allowing for controlled execution and error handling.

When loadfile executes, it attempts to open the specified file, read its contents, and compile the code. If successful, it returns the compiled chunk as a function. If the file cannot be opened or if there is a compilation error, it returns nil and an error message. To run the loaded chunk, a caller must invoke the returned function, typically after additional setup or sandboxing as needed.

A common pattern is: local chunk, err = loadfile("script.lua"); if not chunk then error(err) end; chunk(). This differs from dofile, which loads and immediately executes the file in one step. Because loadfile delays execution, it can be used to implement custom loading workflows, perform preflight checks, or run code within a restricted environment.

Environment and sandboxing considerations are important. In older Lua versions the environment of the loaded chunk could be manipulated using setfenv, while newer versions separate loading from execution and use _ENV or explicit environments. When using loadfile in a security-sensitive context, it is important to control what the chunk can access during execution.

See also dofile, load, setfenv, and the _ENV mechanism.