The Circus

Q: What do Seaport Orders and The Circus have in common?

A: They're both intents.

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Usage

TheCircusZone is a proof-of-concept Seaport Zone that takes extraData in the form of an abi-encoded struct:

struct ArbitraryIntentData {
    bytes initData;
    bytes32 salt;
}

This data is used to CREATE2 an ephemeral smart contract designed to be a container to execute arbitrary logic within its constructor, without actually writing code to the chain.

This allows for expressive, arbitrary assertions to be made by TheCircusZone, to emphasize Seaport's potential as an "intent" protocol; a signed Seaport order will not be fulfillable unless all ConsiderationItems are satisified in addition to any arbitrary checks specified by an ArbitraryIntent. Since Zones can both read and write arbitrary data, this allows for a wide range of use cases.

TheCircusZone

A simple zone that reads the extraData from the ZoneParameters as an ArbitraryIntentData struct. It calls CREATE2 using this data, and reverts if any data returned, otherwise passing the validateOrder check. The resulting address is checked against the zoneHash of the order, meaning all logic must be set at the time of order creation.

ArbitraryIntent

An abstract template contract for executing arbitrary code within the context of a Seaport Zone – "intent" logic is implemented in the expressIntent() function. If a revert is specified with a non-zero amount of data, TheCircusZone will revert with this data, otherwise, the validateOrder check will pass.

test/helpers/SpecificIntent.sol

A very simple "specific" Intent that reverts if a particular smart contract has not been deployed.

FAQ

What are intents?

idk tbh

What is Seaport?

Seaport is the most powerful, extensible, and gas-efficient token settlement platform on EVM chains.

What are Seaport Zones?

Zones are accounts that must authorize a Seaport order as part of fulfillment. Strictly speaking, they don't have to be smart contracts, but they're a lot more interesting if they are.

Seaport will call validateOrder on smart contract Zones specified by orders' OrderParameters, after all token transfers have been made. This means Zones can make arbitrary assertions about the state of the chain after the order has been executed, such as:

This account should have at least X balance of Y token, and at most B balance of C token

without being prescriptive about how exactly that happens.

Since Seaport makes a stateful call, Zones may also perform on-chain update.

Why CREATE2 "intents?"

To highlight that Seaport Zones can do pretty much anything

Isn't that pretty gas-intensive?

Yeah

Can't I just deploy a custom Seaport Zone for my use-case?

Yeah

How is "The Circus" different from normal Seaport Zones?

It's not