# `gno.land/r/moul/demo/data`

Step 3 of the `r/moul/demo` walkthrough: realm state that persists between
transactions.

```go
var total int

func init()          { total = 1000 }
func Add(nb int) int { total += nb; return total }
```

`total` is a package-level variable in a realm, so the VM persists it after
every call. `init` runs once, at deploy time, not on each call. Call `Add(42)`
then `Add(295)` and the second call returns 1337: the mutation from the first
one was committed to chain storage.

That is the whole difference between a `p/` package (no state of its own) and
an `r/` realm.

Previous: [`args`](../args). Next: [`render`](../render) exposes state through
gnoweb.

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---

Part of **[moul/gno-contracts](https://github.com/moul/gno-contracts)** — moul's versioned gno.land contracts. See the repository for the full catalog, build/test tooling, and usage.

**On mainnet:** [![deployment status](https://gnoscope.com/_badges/shield/status/r/moul/demo/data/v0?network=mainnet)](https://gnoscope.com/realm/r/moul/demo/data/v0) [![transactions](https://gnoscope.com/_badges/shield/txs/r/moul/demo/data/v0?network=mainnet)](https://gnoscope.com/realm/r/moul/demo/data/v0) [![unique callers](https://gnoscope.com/_badges/shield/users/r/moul/demo/data/v0?network=mainnet)](https://gnoscope.com/realm/r/moul/demo/data/v0) [![deployed revision](https://gnoscope.com/_badges/shield/version/r/moul/demo/data/v0?network=mainnet)](https://gnoscope.com/realm/r/moul/demo/data/v0)

> ⚠️ **Disclaimer:** provided as-is, without warranty; not security-audited. Full disclaimer: [DISCLAIMER](https://github.com/moul/gno-contracts/blob/main/DISCLAIMER.md).

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