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Purpose

The purpose of the pricing contracts is to serve as token-price data sources for ecosystem applications. The token pricers can be found in 2 different categories: Developers may choose to adapt their preferred third-party solution for token pricing: Configured pricing modules are required for the following rules:

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Price Format

  • Price is in wei of US Dollars: 1 dollar is represented by 1 _ 10^18, and 1 cent is represented 1 _ 10^16 in these contracts. This is done to have precision over the price, and to account for the possibility of tokens with extremely low prices.
  • The price is given for a whole token:
    • For Fungible Tokens: just like regular market data outlets, the price will be given for a whole token without decimals. e.g 1 ETH.
    • For Non-Fungible-Tokens: even in the case of a fractionalized NFT, the price is still given for the whole token and not for its fractions.

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Examples:

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ERC20s

Let’s say we have the ERC20 called Frankenstein which has 18 decimals (1 Frankenstein = 1 * 10^18 wei of a Frankenstein). Let’s imagine that each Frankenstein is worth exactly $0.55 US Dollars (55 ¢). In this case, the price for the token will be 55 * 10^16.

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ERC721s

Let’s say we have the NFT collection called FrankensteinNFT. Let’s imagine that the FrankensteinNFT with Id 222 is worth exactly $500.00 US Dollars. In this case, the price for the token will be 500 * 10^18.

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Third-Party Solutions

Developers may choose their preferred third-party solutions for token pricing. In order for these to be able to communicate properly with the protocol, they simply have to deploy an adapter contract -if necessary- that implements the protocol interface for the respective kind of token. This way, the adapter contract will live in the middle of the application and the external pricer contract in order to format the request and response between these two elements: 
    _______________        ___________        ________________________
    | Application | <----> | Adapter | <----> | Third-Party Solution |
    ---------------        -----------        ------------------------
Developers may choose to implement and deploy an adapter contract per token standard (one for ERC20 and another for ERC721), or to implement both in a single contract to deploy. No matter the route taken, the appManager Handler must have both pricer addresses set in order to properly work.