Addresses

An address on the Tezos blockchain is a string whose suffix is the hash of the public key of a peer. If that peer is a smart contract, the address is prefixed by the string "KT1"; otherwise, it is associated to an implicit account, prefixed by "kt1", "kt2" or "kt3", depending on the hashing function.

There are two ways to define and handle adresses.

The address type

The address type in LIGO denotes a well-formed Tezos address of any kind (tz1, tz2, tz3, tz4, KT1 etc.). Currently, such addresses are created by casting a string to the address type. Beware of failures if the address is invalid. Consider the following examples.

const my_account: address =

"tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" as address;

Note that a literal value of type address does not entail that it is the valid address on the chain, only that it is well-formed.

Self

The call Tezos.self(entrypoint) is the address of the current smart contract, that is, the smart contract containing the call. For the address of the smart contract actually executing the call, because it is embedded in a lambda sent to another smart contract, use Tezos.get_self_address instead. The string entrypoint is the name of a valid entrypoint such that entrypoint is not "%default", or the empty string denoting the "%default" entrypoint (which is the root of the smart contract parameter if no "%default" entrypoint is explicitly defined). If the contract does not have the specified entrypoint, the call results in an type checking error.

Naming convention: if you are using entrypoints, use "%bar" to denote the constructor "Bar" of the parameter, in turn corresponding to the entrypoint function bar. If you are not using entrypoints: use "%default".

let check = () => Tezos.self("%default");

Self-Address

Often you want to get the address of the contract being executed. You can do it with Tezos.get_self_address. When used inside a lambda, that function returns the address of the contract executing the lambda, which can be different from the address of the contract in which the call is written.

const current_addr : address = Tezos.get_self_address();

Sender

The sender is the address of the contract (that is, a smart contract or an implicit account) that initiated the current internal transaction. Note that, if transactions have been chained, that address could be different from the source.

const sender: address = Tezos.get_sender();

Source

The source is the address of the implicit account that initiated the current transaction. If transactions have been chained, that address is different from the sender.

const source: address = Tezos.get_source();

The contract type

In order to handle addresses that denote an originated account on the chain, we need a value of type contract. In fact, it is a type parameterised by the type of the contract's parameter. Contrary to the type address, there are no literal values of the type contract, so values have to be created by means of predefined functions.

The call Tezos.implicit_account(kh) casts the public key hash kh into the address of its implicit account. Note that addresses of implicit accounts always have the type contract<unit>.