Create a sale contract

As discussed in Contract architecture, you can use a sales-specific contract to manage how tokens are sold—for example, by offering tokens for sale in a conventional auction sale contract or a dutch auction sale contract.

Although this is a flexible system for managing sales, sales-specific contracts must be registered in the policy manager to ensure that the policy manager can enforce the proper collection and distribution of tokens and funds. Before you can register a sales-specific contract, the contract must be reviewed by an auditor to ensure that the contract logic is safe to use.

If you want to create your own sales-specific contract, you can implement the enforce-quote-update interface in your contract, then open a pull request in the Marmalade Github repository to begin the review process.

Note that creating a sales-specific contract isn't necessary in most cases. You can implement sales-related logic directly in a policy and attach the policy to a token instead of creating a separate contract.

The sale contract interface is a lightweight interface that must be implemented in any sale contract. The interface is used by the policy manager to enforce the logic defined in the contract. The interface is defined as follows:

The function enforce-quote-update is called from the buy step in the ledger and takes two parameters:

You can specify the sale contract to use by providing the module name for the contract as part of the quote specification when calling the offer function in the ledger. The following example illustrates the quote specification with the sale-type set to use the marmalade-sale.conventional-auction sale contract:

Note that when you reference a specific sale-type, the sale-price for the offer must be 0.0 because the referenced contract is responsible for updating the final price during the buy step.