Skeleton Facets

In the context of platform configuration and deployment, the term skeleton refers to a main facet that provides mandatory functionality used on the platform. Skeleton facets must be included when deploying a new platform. The basic configuration for both Sale and Sale with Buyback requires the following facets to be selected:

Sale requires 3 skeleton Facets:

• CreateFractionsSkeleton - Provides a set of functions to create fractions.
• PurchaseSkeleton - Exposes functions that allow users to purchase fractions.
• ReceiveSkeleton - Provides functionality to receive funds collected from the sale.

Sale with buyback requires 5 skeleton Facets:

• CreateFractionsSkeleton - Provides a set of functions to create fractions.
• PurchaseSkeleton - Exposes functions that allow users to purchase fractions.
• ReceiveSkeleton - Provides functionality to receive funds collected from the sale.
• BuybackSkeleton - Enables the buyback functionality for users.
• ReceiveAfterBuybackSkeleton - Allows users to retrieve principal and interest after the buyback.

If a use-case instance falls under the Sale category, then it is clear that there is no Buyback or ReceiveAfterBuyback facets involved.

Eligibility Verification

Each skeleton implements the eligibility interface, which verifies whether a particular user address can invoke a specific function. For instance, the Purchase skeleton interacts with the IPurchaseEligibilityFacet interface, which allows checking whether a user can execute the purchase function.

Below is an example of the function call to check the account eligibility in the Purchase skeleton:

IPurchaseEligibilityFacet(address(this)).checkPurchaserEligibility(campaignId, account, amountOfFractions);

The implementation of eligibility checks enables a robust mechanism where only accounts (users) matching specific criteria can participate in a sale.

Developers are free to customize the eligibility verification mechanism by modifying the corresponding eligibility facets.