Issue To Be Solved

Here's an example: https://play.onflow.org/2d6bf889-ac32-4de4-9a79-a25ddf1d5236?type=tx&id=73c0651f-3aba-4150-81ea-5ccaa4b20c61

The same (duplicate code) contract deployed to 0x02 and 0x03, and in the transaction, I'm trying to reference the two duplicated contracts:

However, it gives an error saying "cannot redeclare contract: FUSD is already declared".

I think this restriction here doesn't make any sense. Yes the contract code is duplicated, but they're deployed to different accounts so can carry with different states / storage spaces.

We should allow referencing these contracts in the cadence environment, either through import .. as ... alias, or other developer-friendly ways. (See suggested solution)

Suggested Solution

1. Import .. as .. alias:

import FUSD as FUSD1 from 0x02
import FUSD as FUSD2 from 0x03

transaction {
  prepare(acct: AuthAccount) {
    let typeFUSD = Type<FUSD1>()
    let typeKibble = Type<FUSD2>()
    log(typeFUSD == typeKibble)
    log(typeFUSD.identifier)
    log(typeKibble.identifier)
  }
}

2. Maybe other developer-friendly way?

Additional Comments:

• Why I think this feature is necessary?
  Let's say here's a scenario like: since each uniswap trading pool shares the same code template from UniswapPair.cdc and deployed as UniswapPair contract. Now say we have 2 pools: FlowUSDT pool and FUSDUSDT pool. Due to the above mentioned error, current developers / arbitrageurs cannot reference these 2 pools in the same contract / transaction code.
  (I know Blocto workarounds this by naming the two pools with different names - but this is silly! Duplicating code adds technical debt and maintainance efforts with no benefit - it also lost permissionless pool deployment and composability then.)

I think this feature will be good for any pool-based defi projects build on flow, and will be beneficial to flow ecosystem composibility as a whole.

• Any comments against this feature is also welcome, let's debate on the pros and cons then :).