Ergo-Native Features
Intermediate
2-4 hoursBabel Fee Box Pattern (Pay Fees in Any Token)
Use Babel boxes so users pay network fees in arbitrary tokens
问题
Users hold tokens but no ERG. They can't transact because they can't pay network fees.
解决方案
Babel fee boxes allow third parties (arbitrageurs) to pay ERG fees in exchange for tokens. Users include a Babel box offering tokens for ERG, and anyone can fulfill it.
工作原理
- 1User creates a Babel fee box: offers X tokens for Y ERG
- 2User's main transaction references Babel box
- 3Arbitrageur sees opportunity: provides ERG, takes tokens
- 4Transaction executes with ERG fees paid by arbitrageur
- 5User's tokens are exchanged for the fee payment
- 6Miners receive ERG as normal - no protocol changes needed
代码示例
{
// Babel Fee Box: offers tokens for ERG
// R4: Token ID being offered
// R5: Token amount offered
// R6: ERG amount requested
// R7: User's address (for any leftover)
val offeredTokenId = SELF.R4[Coll[Byte]].get
val offeredAmount = SELF.R5[Long].get
val requestedErg = SELF.R6[Long].get
val userAddress = SELF.R7[Coll[Byte]].get
// Verify box has the offered tokens
val hasTokens = SELF.tokens(0)._1 == offeredTokenId &&
SELF.tokens(0)._2 >= offeredAmount
// Babel box can be consumed if:
// 1. User receives the requested ERG, OR
// 2. User cancels (returns tokens to self)
val fulfilled = {
// User receives ERG
OUTPUTS.exists(o =>
o.propositionBytes == userAddress &&
o.value >= requestedErg
)
}
val cancelled = {
// User gets tokens back
OUTPUTS.exists(o =>
o.propositionBytes == userAddress &&
o.tokens(0)._1 == offeredTokenId &&
o.tokens(0)._2 >= offeredAmount
)
}
hasTokens && (fulfilled || cancelled)
}Babel fee box offers tokens in exchange for ERG. Anyone can fulfill by providing ERG, or the user can cancel.
使用场景
- →Onboarding users with only tokens
- →Token-only wallets and dApps
- →Gasless transactions for end users
- →Improved UX for token transfers
- →Fee abstraction layer
安全注意事项
- !Set reasonable exchange rates to attract arbitrageurs
- !Consider slippage in volatile markets
- !Babel boxes can be front-run - use appropriate rates
- !Include cancellation option for users
参考资源
手续费说明
Users pay in tokens at a premium over ERG. Arbitrageurs profit from the spread. No protocol-level changes needed.