What's the best way to customize transfer behavior of fungible asset?

[0x-j]

Asked by vpawar46 on discord

Dear Aptos Developers, I need an urgent help, We are in process of developing customize Fungible assets which will have custom behaviour for transfer function. Same token should behave differently based on the source how it got minted. there are 3 category of same token and based on business logic users should able to use transfer methods. Is there any documentation you can refer. Should write everything custom or should we use default Fungible Asset module and overrrid transfer method of it. Looking for your support. Many Thanks!

[runtian-zhou]

I'm working on this! See aptos-labs/aptos-core#12490

[gregnazario]

More concretely:

Today: you cannot customize transfer function on fungible assets, the functionality is defined statically.

In development: Dispatchable Fungible Assets, should allow for the ability to override this configuration.

You can additionally make custom logic, but any dex, wallet, or other system would need to recognize the custom logic.

[0x-j]

Adding to what Greg said, if you fork the fungible asset module, your asset wouldn't be compatible with the dex on Aptos. Because on Aptos, module is the standard (i.e. only asset created by 0x1::fungible_asset is recognized by dex), this is similar to Solana. It's different from Ethereum where interface is the standard

[davidiw]

You can make custom transfer functions that must be respected, but they have limited interoperability as the dapp would need to know about this function. @runtian-zhou's proposal would allow overriding the functions thus making discoverability a non-issue.

1. Define a module that manages your FungibleAsset
2. Within it, build a management struct that contains the TransferRef
3. Write your custom transfer function that uses this ref and withdraw_with_ref and deposit_with_ref
4. freeze the asset store

With @runtian-zhou's change, you would expose your own withdraw and deposit functions that would be picked up by the default withdraw / deposit functions. You would still need the TransferRef to then call into withdraw_with_ref and deposit_with_ref.