cs2010 Notes: Environments

Notional Machine

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Real machine:

• RAM
• Memory addresses
• Instructions

Lua Notional Machine:

• Lines of code
• Variables
• Environments (“scopes”)

Environments / Variable Scope

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Simple examples

• File local
• Function local
• Masking
• Nested functions
• Lexical closures (e.g. counter)

local aa = 5
print(aa)

local function zz()
        local aa = 7
        print(aa)
end

zz()

print(aa)