Safe Navigation

Accessing deeply nested fields which can potentially be nil was problematic, because you'd need an unreasonable amount of guard clauses to prevent an "attempt to index nil" error. Pluto now offers this syntax:

Basic Usage

local value = a?.b?.c?.d

In this example, every field is nil. However, this does not throw an error. It simply returns nil. Without safe table navigation, this would've returned several "attempt to index nil" errors.

Practical Usage

-- Pretend userConfig is parsed from a JSON file, or something.

--- Returning the user's preferred color, or Red if they have no preferred color.
local function get_color()
    return userConfig.colors?.preferred ?? "Red"
end

print(get_color())

info

These cannot be used for statements, like a?.b?.c = 0. They're only valid as expressions.

Safe Navigation was written by Sven Olsen.