LP Tokens — Curve 1.0.0 documentation (2024)

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Curve StableSwap Exchange: LP Tokens
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In exchange for depositing coins into a Curve pool (see Curve Pools), liquidity providers receive pool LP tokens. A Curve pool LP token is an ERC20 contract specific to the Curve pool. Hence, LP tokens are transferrable. Holders of pool LP tokens may stake the token into a pool’s liquidity gauge in order to receive CRV token rewards. Alternatively, if the LP token is supported by a metapool, the token may be deposited into the respective metapool in exchange for the metapool’s LP token (see here).

The following versions of Curve pool LP tokens exist:

CurveTokenV1: LP token targetting Vyper ^0.1.0-beta.16
CurveTokenV2: LP token targetting Vyper ^0.2.0
CurveTokenV3: LP token targetting Vyper ^0.2.0 with gas optimizations

The version of each pool’s LP token can be found in the Deployment Addresses.

Note

For older Curve pools the token attribute is not always public and a getter has not been explicitly implemented.

Curve Token V1

The implementation for a Curve Token V1 may be viewed on GitHub.

CurveToken.name() → string[64]: view

Get the name of the token.

>>> lp_token.name()'Curve.fi yDAI/yUSDC/yUSDT/yBUSD'

CurveToken.symbol() → string[32]: view

Get the token symbol.

>>> lp_token.symbol()'yDAI+yUSDC+yUSDT+yBUSD'

CurveToken.decimals() → uint256: view

Get the number of decimals for the token.

>>> lp_token.decimals()18

CurveToken.balanceOf(account: address) → uint256: view

Get the token balance for an account.

account: Address to get the token balance for

>>> lp_token.balanceOf("0x69fb7c45726cfe2badee8317005d3f94be838840")72372801850459006740117197

CurveToken.totalSupply() → uint256: view

Get the total token supply.

>>> lp_token.totalSupply()73112516629065063732935484

CurveToken.allowance(_owner: address, _spender: address) → uint256: view

Get the allowance of an account to spend on behalf of some other account.

_owner: Account that is paying when _spender spends the allowance
_spender: Account that can spend up to the allowance

Returns the allowance of _spender for _owner.

CurveToken.transfer(_to: address, _value: uint256) → bool

Transfer tokens to a specified address.

_to: Receiver of the tokens
_value: Amount of tokens to transfer

Returns True if the transfer succeeded.

CurveToken.transferFrom(_from: address, _to: address, _value: uint256) → bool

Transfer tokens from one address to another. Note that while this function emits a Transfer event, this is not required as per the specification, and other compliant implementations may not emit the event.

_from: Address which you want to send tokens from
_to: Address which you want to transfer to
_value: Amount of tokens to be transferred

Returns True if transfer succeeded.

CurveToken.approve(_spender: address, _value: uint256) → bool

Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.

Beware that changing an allowance with this method brings the risk that someone may use both the old and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this race condition is to first reduce the spender’s allowance to 0 and set the desired value afterwards (see this GitHub issue).

_spender: Address which will spend the funds.
_value: Amount of tokens to be spent.

Returns True if approval succeeded.

Warning

For Curve LP Tokens V1 and V2, non-zero to non-zero approvals are prohibited. Instead, after every non-zero approval, the allowance for the spender must be reset to 0.

Minter Methods

The following methods are only callable by the minter (private attribute).

Curve Token V2

The implementation for a Curve Token V2 may be viewed on GitHub.

Note

Compared to Curve Token v1, the following changes have been made to the API:

minter attribute is public and therefore a minter getter has been generated
name and symbol attributes can be set via set_name
mint method returns bool
burnFrom method returns bool
burn method has been removed

Warning

For Curve LP Tokens V1 and V2, non-zero to non-zero approvals are prohibited. Instead, after every non-zero approval, the allowance for the spender must be reset to 0.

CurveToken.minter() → address: view: Getter for the address of the minter of the token.

CurveToken.set_name(_name: String[64], _symbol: String[32])

Set the name and symbol of the token.

_name: New name of token
_symbol: New symbol of token

This method can only be called by minter.

CurveToken.mint(_to: address, _value: uint256) → bool

Mint an amount of the token and assign it to an account. This encapsulates the modification of balances such that the proper events are emitted.

Returns True if not reverted.

CurveToken.burnFrom(_to: address, _value: uint256) → bool

Burn an amount of the token from a given account.

_to: Account whose tokens will be burned
_value: Amount that will be burned

Returns True if not reverted.

Curve Token V3

The Curve Token V3 is more gas efficient than versions 1 and 2.

Note

Compared to the Curve Token V2 API, there have been the following changes:

increaseAllowance and decreaseAllowance methods added to mitigate race conditions

The implementation for a Curve Token V3 may be viewed on GitHub.

CurveToken.increaseAllowance(_spender: address, _added_value: uint256) → bool

Increase the allowance granted to _spender by the msg.sender.

This is alternative to approve that can be used as a mitigation for the potential race condition.

_spender: Address which will transfer the funds
_added_value: Amount of to increase the allowance

Returns True if success.

CurveToken.decreaseAllowance(_spender: address, _subtracted_value: uint256) → bool

Decrease the allowance granted to _spender by the msg.sender.

This is alternative to {approve} that can be used as a mitigation for the potential race condition.

_spender: Address which will transfer the funds
_subtracted_value: Amount of to decrease the allowance

Returns True if success.