Namespaces in Cairo

A main use case for namespaces is to define an interface to your contract that the outside world (other contracts) can call. For example, if in your contract you had the 2 functions increase_balance and get_balance, you could then create a namespace with the function names (omit the bodies):

@contract_interface

namespace IBalanceContract:

func increase_balance(amount : felt):

end



func get_balance() -> (res : felt):

end

end

Now other contracts can call your contract like:

IBalanceContract.increaseBalance(contract_address=contract_address,amount=amount)

Notice how the contract_address was passed in as the first argument to the interface function, even though it was not explicitly defined in the interface/namespace

ㅤ This answer was originally posted on Triality