47 lines
1.7 KiB
Markdown
47 lines
1.7 KiB
Markdown
---
|
|
id: entrypoints
|
|
title: Entrypoints
|
|
---
|
|
|
|
Entrypoints serve as a gate to our smart contracts. In LIGO each entrypoint is a function that accepts two arguments - first one is the parameter used to invoke the contract, and the second is the current storage of the contract. Each entrypoint has to return a list of operations to apply as a result of the smart contract call, and a new storage value.
|
|
|
|
> If you don't want to update the storage, don't worry, just re-cycle your last storage value.
|
|
|
|
## Defining an entry point
|
|
|
|
Contract below is effectively an empty contract, that takes a `unit` as a parameter, and returns a `unit` as well.
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
```pascaligo
|
|
function main (const p : unit ; const s : unit) : (list(operation) * unit) is
|
|
block {skip} with ((nil : list(operation)), s)
|
|
```
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
## Multiple entry points
|
|
|
|
Multiple entrypoints are currently not supported in Michelson yet, however with Ligo, you can work that around by using variants & pattern matching.
|
|
|
|
In the example below we have a simple counter contract, that can be either `Increment(int)`-ed, or `Decrement(int)`-ed.
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
```pascaligo
|
|
// variant defining pseudo multi-entrypoint actions
|
|
type action is
|
|
| Increment of int
|
|
| Decrement of int
|
|
|
|
// real entrypoint that re-routes the flow based on the action (parameter) provided
|
|
function main (const action: action ; const counter: int) : (list(operation) * int) is
|
|
block {skip} with ((nil : list(operation)),
|
|
case action of
|
|
| Increment(number) -> counter + number
|
|
| Decrement(number) -> counter - number
|
|
end)
|
|
```
|
|
|
|
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|