323 lines
7.5 KiB
Markdown
323 lines
7.5 KiB
Markdown
---
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id: current-reference
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title: Current - Things relating to the current execution context
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---
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## Current.balance() : tez
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Get the balance for the contract.
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<!--DOCUSAURUS_CODE_TABS-->
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<!--PascaLIGO-->
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```pascaligo
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function main (const p : unit; const s: tez) : list(operation) * storage is
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((nil : list(operation)), balance)
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```
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<!--CameLIGO-->
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```cameligo
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let main (p, s : unit * storage) =
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([] : operation list), balance
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```
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<!--ReasonLIGO-->
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```reasonligo
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let main = (p: unit, storage) => ([]: list(operation), balance);
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```
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<!--END_DOCUSAURUS_CODE_TABS-->
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## Current.time() : timestamp
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Returns the current time as a [unix timestamp](https://en.wikipedia.org/wiki/Unix_time).
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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:
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### Examples
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#### 24 hours from now
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<!--DOCUSAURUS_CODE_TABS-->
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<!--Pascaligo-->
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```pascaligo group=b
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const today: timestamp = now;
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const one_day: int = 86400;
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const in_24_hrs: timestamp = today + one_day;
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const some_date: timestamp = ("2000-01-01T10:10:10Z" : timestamp);
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const one_day_later: timestamp = some_date + one_day;
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```
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<!--CameLIGO-->
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```cameligo group=b
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let today: timestamp = Current.time
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let one_day: int = 86400
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let in_24_hrs: timestamp = today + one_day
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let some_date: timestamp = ("2000-01-01t10:10:10Z" : timestamp)
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let one_day_later: timestamp = some_date + one_day
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```
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<!--ReasonLIGO-->
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```reasonligo group=b
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let today: timestamp = Current.time;
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let one_day: int = 86400;
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let in_24_hrs: timestamp = today + one_day;
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let some_date: timestamp = ("2000-01-01t10:10:10Z" : timestamp);
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let one_day_later: timestamp = some_date + one_day;
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```
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<!--END_DOCUSAURUS_CODE_TABS-->
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#### 24 hours ago
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<!--DOCUSAURUS_CODE_TABS-->
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<!--Pascaligo-->
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```pascaligo group=c
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const today: timestamp = now;
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const one_day: int = 86400;
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const in_24_hrs: timestamp = today - one_day;
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```
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<!--CameLIGO-->
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```cameligo group=c
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let today: timestamp = Current.time
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let one_day: int = 86400
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let in_24_hrs: timestamp = today - one_day
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```
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<!--ReasonLIGO-->
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```reasonligo group=c
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let today: timestamp = Current.time;
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let one_day: int = 86400;
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let in_24_hrs: timestamp = today - one_day;
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```
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<!--END_DOCUSAURUS_CODE_TABS-->
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#### Comparing timestamps
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You can also compare timestamps using the same comparison operators as for numbers:
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<!--DOCUSAURUS_CODE_TABS-->
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<!--Pascaligo-->
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```pascaligo group=c
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const not_tommorow: bool = (now = in_24_hrs)
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```
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<!--CameLIGO-->
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```cameligo group=c
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let not_tomorrow: bool = (Current.time = in_24_hrs)
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```
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<!--ReasonLIGO-->
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```reasonligo group=c
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let not_tomorrow: bool = (Current.time == in_24_hrs);
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```
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<!--END_DOCUSAURUS_CODE_TABS-->
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## Current.amount() : tez
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Get the amount of tez provided by the sender to complete this transaction.
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<!--DOCUSAURUS_CODE_TABS-->
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<!--PascaLIGO-->
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```pascaligo
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function check (const p: unit) : int is
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begin
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var result : int := 0;
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if amount = 100tz then
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result := 42
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else
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result := 0
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end with result
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```
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<!--CameLIGO-->
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```cameligo
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let check_ (p: unit) : int = if Current.amount = 100tz then 42 else 0
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```
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<!--ReasonLIGO-->
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```reasonligo
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let check_ = (p: unit) : int =>
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if (Current.amount == 100tz) {
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42;
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}
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else {
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0;
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};
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```
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<!--END_DOCUSAURUS_CODE_TABS-->
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## Current.sender() : address
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Get the address that initiated the current transaction.
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<!--DOCUSAURUS_CODE_TABS-->
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<!--PascaLIGO-->
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```pascaligo
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function main (const p: unit) : address is sender
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```
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<!--CameLIGO-->
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```cameligo
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let main (p: unit) : address = Current.sender
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```
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<!--ReasonLIGO-->
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```reasonligo
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let main = (p: unit) : address => Current.sender;
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```
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<!--END_DOCUSAURUS_CODE_TABS-->
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## Current.address(c: a' contract) : address
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Get the address associated with a `contract`.
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<!--DOCUSAURUS_CODE_TABS-->
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<!--PascaLIGO-->
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```pascaligo
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function main (const p : key_hash) : address is block {
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const c : contract(unit) = implicit_account(p) ;
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} with address(c)
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```
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<!--CameLIGO-->
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```cameligo
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let main (p : key_hash) =
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let c : unit contract = Current.implicit_account p in
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Current.address c
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```
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<!--ReasonLIGO-->
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```reasonligo
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let main = (p : key_hash) : address => {
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let c : contract(unit) = Current.implicit_account(p) ;
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Current.address(c) ;
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};
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```
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<!--END_DOCUSAURUS_CODE_TABS-->
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## Current.self_address() : address
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Get the address of the currently running contract.
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<!--DOCUSAURUS_CODE_TABS-->
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<!--PascaLIGO-->
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```pascaligo
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function main (const p: unit) : address is self_address
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```
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<!--CameLIGO-->
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```cameligo
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let main (p: unit) : address = Current.self_address
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```
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<!--ReasonLIGO-->
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```reasonligo
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let main = (p: unit): address => Current.self_address;
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```
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<!--END_DOCUSAURUS_CODE_TABS-->
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## Current.implicit_account(p: key_hash) : a' contract
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Get the default contract associated with an on-chain keypair. This contract
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doesn't execute code, instead it exists to receive money on behalf of a keys
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owner.
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<!--DOCUSAURUS_CODE_TABS-->
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<!--PascaLIGO-->
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```pascaligo
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function main (const kh: key_hash) : contract(unit) is implicit_account(kh)
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```
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<!--CameLIGO-->
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```cameligo
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let main (kh: key_hash) : unit contract = Current.implicit_account kh
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```
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<!--ReasonLIGO-->
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```reasonligo
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let main = (kh: key_hash): contract(unit) => Current.implicit_account(kh);
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```
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<!--END_DOCUSAURUS_CODE_TABS-->
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## Current.source() : address
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Get the _originator_ of the current transaction. That is, if a chain of transactions
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led to the current execution get the address that began the chain. Not to be confused
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with `Current.sender`, which gives the address of the contract or user which directly
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caused the current transaction.
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> ⚠️
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> There are a few caveats you should keep in mind before using `SOURCE` over `SENDER`:
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>
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> 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
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> 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.
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<!--DOCUSAURUS_CODE_TABS-->
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<!--PascaLIGO-->
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```pascaligo
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function main (const p: unit) : address is source
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```
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<!--CameLIGO-->
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```cameligo
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let main (p: unit) : address = Current.source
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```
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<!--ReasonLIGO-->
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```reasonligo
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let main = (p: unit) : address => Current.source;
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```
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<!--END_DOCUSAURUS_CODE_TABS-->
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## Current.failwith(error_message: string) : a'
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Cause the contract to fail with an error message.
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> ⚠ Using this currently requires a type annotation on the failwith to unify it
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> with the type of whatever other code branch it's on.
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<!--DOCUSAURUS_CODE_TABS-->
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<!--PascaLIGO-->
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```pascaligo
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function main (const p : param; const s : unit) : list(operation) * unit is
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block {
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case p of
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| Zero (n) -> if n > 0n then failwith("fail") else skip
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| Pos (n) -> if n > 0n then skip else failwith("fail")
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end
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}
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with ((nil : list(operation)), s)
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```
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<!--CameLIGO-->
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```cameligo
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let main (p: unit) storage =
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if true then failwith "This contract always fails" else ()
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```
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<!--ReasonLIGO-->
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```reasonligo
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let main = (p: unit, storage) =>
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if (true) {
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failwith("This contract always fails");
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} else {
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();
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};
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```
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<!--END_DOCUSAURUS_CODE_TABS-->
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