--- id: current-reference title: Current - Things relating to the current execution context --- ## Current.balance() : tez Get the balance for the contract. ```pascaligo function main (const p : unit; const s: tez) : list(operation) * tez is ((nil : list(operation)), balance) ``` ```cameligo let main (p, s : unit * tez) = ([] : operation list), balance ``` ```reasonligo let main = ((p,s): (unit, tez)) => ([]: list(operation), balance); ``` ## Current.time() : timestamp Returns the current time as a [unix timestamp](https://en.wikipedia.org/wiki/Unix_time). In LIGO, timestamps are type compatible in operations with `int`(s). This lets you set e.g. time constraints for your smart contracts like this: ### Examples #### 24 hours from now ```pascaligo group=b const today: timestamp = now; const one_day: int = 86400; const in_24_hrs: timestamp = today + one_day; const some_date: timestamp = ("2000-01-01T10:10:10Z" : timestamp); const one_day_later: timestamp = some_date + one_day; ``` ```cameligo group=b let today: timestamp = Current.time let one_day: int = 86400 let in_24_hrs: timestamp = today + one_day let some_date: timestamp = ("2000-01-01t10:10:10Z" : timestamp) let one_day_later: timestamp = some_date + one_day ``` ```reasonligo group=b let today: timestamp = Current.time; let one_day: int = 86400; let in_24_hrs: timestamp = today + one_day; let some_date: timestamp = ("2000-01-01t10:10:10Z" : timestamp); let one_day_later: timestamp = some_date + one_day; ``` #### 24 hours ago ```pascaligo group=c const today: timestamp = now; const one_day: int = 86400; const in_24_hrs: timestamp = today - one_day; ``` ```cameligo group=c let today: timestamp = Current.time let one_day: int = 86400 let in_24_hrs: timestamp = today - one_day ``` ```reasonligo group=c let today: timestamp = Current.time; let one_day: int = 86400; let in_24_hrs: timestamp = today - one_day; ``` #### Comparing timestamps You can also compare timestamps using the same comparison operators as for numbers: ```pascaligo group=c const not_tommorow: bool = (now = in_24_hrs) ``` ```cameligo group=c let not_tomorrow: bool = (Current.time = in_24_hrs) ``` ```reasonligo group=c let not_tomorrow: bool = (Current.time == in_24_hrs); ``` ## Current.amount() : tez Get the amount of tez provided by the sender to complete this transaction. ```pascaligo function check (const p: unit) : int is begin var result : int := 0; if amount = 100tz then result := 42 else result := 0 end with result ``` ```cameligo let check_ (p: unit) : int = if Current.amount = 100tz then 42 else 0 ``` ```reasonligo let check_ = (p: unit) : int => if (Current.amount == 100tz) { 42; } else { 0; }; ``` ## Current.sender() : address Get the address that initiated the current transaction. ```pascaligo function main (const p: unit) : address is sender ``` ```cameligo let main (p: unit) : address = Current.sender ``` ```reasonligo let main = (p: unit) : address => Current.sender; ``` ## Current.address(c: a' contract) : address Get the address associated with a `contract`. ```pascaligo function main (const p : key_hash) : address is block { const c : contract(unit) = implicit_account(p) ; } with address(c) ``` ```cameligo let main (p : key_hash) = let c : unit contract = Current.implicit_account p in Current.address c ``` ```reasonligo let main = (p : key_hash) : address => { let c : contract(unit) = Current.implicit_account(p) ; Current.address(c) ; }; ``` ## Current.self_address() : address Get the address of the currently running contract. ```pascaligo function main (const p: unit) : address is self_address ``` ```cameligo let main (p: unit) : address = Current.self_address ``` ```reasonligo let main = (p: unit): address => Current.self_address; ``` ## Current.implicit_account(p: key_hash) : a' contract Get the default contract associated with an on-chain keypair. This contract doesn't execute code, instead it exists to receive money on behalf of a keys owner. ```pascaligo function main (const kh: key_hash) : contract(unit) is implicit_account(kh) ``` ```cameligo let main (kh: key_hash) : unit contract = Current.implicit_account kh ``` ```reasonligo let main = (kh: key_hash): contract(unit) => Current.implicit_account(kh); ``` ## Current.source() : address Get the _originator_ of the current transaction. That is, if a chain of transactions led to the current execution get the address that began the chain. Not to be confused with `Current.sender`, which gives the address of the contract or user which directly caused the current transaction. > ⚠️ > There are a few caveats you should keep in mind before using `SOURCE` over `SENDER`: > > 1. SOURCE will never be a contract, so if you want to allow contracts (multisigs etc) to operate your contract, you need to use SENDER > 2. https://vessenes.com/tx-origin-and-ethereum-oh-my/ -- in general it is somewhat unsafe to assume that SOURCE understands everything that's going to happen in a transaction. If SOURCE transfers to a malicious (or sufficiently attackable) contract, that contract might potentially transfer to yours, without SOURCE's consent. So if you are using SOURCE for authentication, you risk being confused. A good historical example of this is bakers paying out delegation rewards. Naive bakers did (and probably still do) just use tezos-client to transfer to whatever KT1 delegates they had, even if those KT1 were malicious scripts. ```pascaligo function main (const p: unit) : address is source ``` ```cameligo let main (p: unit) : address = Current.source ``` ```reasonligo let main = (p: unit) : address => Current.source; ``` ## Current.failwith(error_message: string) : a' Cause the contract to fail with an error message. > ⚠ Using this currently requires a type annotation on the failwith to unify it > with the type of whatever other code branch it's on. ```pascaligo function main (const p : int; const s : unit) : list(operation) * unit is block { if p > 10 then failwith("fail") else skip; } with ((nil : list(operation)), s) ``` ```cameligo let main (p,s: unit * unit) = if true then failwith "This contract always fails" else () ``` ```reasonligo let main = ((p,s): (unit, unit)) => if (true) { failwith("This contract always fails"); } else { (); }; ```