Curve Token V1
Token Methods¶
CurveToken.name
¶
CurveToken.name() → string[64]: view
Get token name.
Source code
name: public(string[64])
...
@public
def __init__(_name: string[64], _symbol: string[32], _decimals: uint256, _supply: uint256):
init_supply: uint256 = _supply * 10 ** _decimals
self.name = _name
self.symbol = _symbol
self.decimals = _decimals
self.balanceOf[msg.sender] = init_supply
self.total_supply = init_supply
self.minter = msg.sender
log.Transfer(ZERO_ADDRESS, msg.sender, init_supply)
CurveToken.symbol
¶
CurveToken.symbol() → string[32]: view
Get token symbol.
Source code
symbol: public(string[32])
...
@public
def __init__(_name: string[64], _symbol: string[32], _decimals: uint256, _supply: uint256):
init_supply: uint256 = _supply * 10 ** _decimals
self.name = _name
self.symbol = _symbol
self.decimals = _decimals
self.balanceOf[msg.sender] = init_supply
self.total_supply = init_supply
self.minter = msg.sender
log.Transfer(ZERO_ADDRESS, msg.sender, init_supply)
CurveToken.decimals
¶
CurveToken.decimals() → uint256: view
Get token precision (decimals).
Source code
decimals: public(uint256)
...
@public
def __init__(_name: string[64], _symbol: string[32], _decimals: uint256, _supply: uint256):
init_supply: uint256 = _supply * 10 ** _decimals
self.name = _name
self.symbol = _symbol
self.decimals = _decimals
self.balanceOf[msg.sender] = init_supply
self.total_supply = init_supply
self.minter = msg.sender
log.Transfer(ZERO_ADDRESS, msg.sender, init_supply)
CurveToken.balanceOf
¶
CurveToken.balanceOf(account: address) → uint256: view
Get token balance for an account.
Input | Type | Description |
---|---|---|
address | address | Address to get the token balance for |
Source code
# NOTE: By declaring `balanceOf` as public, vyper automatically generates a 'balanceOf()' getter
# method to allow access to account balances.
# The _KeyType will become a required parameter for the getter and it will return _ValueType.
# See: https://vyper.readthedocs.io/en/v0.1.0-beta.8/types.html?highlight=getter#mappings
balanceOf: public(map(address, uint256))
...
@public
def __init__(_name: string[64], _symbol: string[32], _decimals: uint256, _supply: uint256):
init_supply: uint256 = _supply * 10 ** _decimals
self.name = _name
self.symbol = _symbol
self.decimals = _decimals
self.balanceOf[msg.sender] = init_supply
self.total_supply = init_supply
self.minter = msg.sender
log.Transfer(ZERO_ADDRESS, msg.sender, init_supply)
CurveToken.totalSupply
¶
CurveToken.totalSupply() → uint256: view
Get total token supply.
Source code
CurveToken.allowance
¶
CurveToken.allowance(_owner: address, _spender: address) → uint256: view
This view method gets the allowance of an address (_spender
) to spend on behalf of some other account _owner
.
Input | Type | Description |
---|---|---|
_spender | address | Account that can spend up to the allowance |
_owner | address | Account that is paying when _spender spends the allowance |
Source code
@public
@constant
def allowance(_owner : address, _spender : address) -> uint256:
"""
@dev Function to check the amount of tokens that an owner allowed to a spender.
@param _owner The address which owns the funds.
@param _spender The address which will spend the funds.
@return An uint256 specifying the amount of tokens still available for the spender.
"""
return self.allowances[_owner][_spender]
CurveToken.transfer
¶
CurveToken.transfer(_to: address, _value: uint256) → bool
Transfer tokens to a specified address. _from
address is implicitly msg.sender
. Returns True
if the transfer succeeds.
Input | Type | Description |
---|---|---|
_to | address | Receiver of the tokens |
_value | uint256 | Amount of tokens to be transferred |
Emits: Transfer
Source code
@public
def transfer(_to : address, _value : uint256) -> bool:
"""
@dev Transfer token for a specified address
@param _to The address to transfer to.
@param _value The amount to be transferred.
"""
# NOTE: vyper does not allow underflows
# so the following subtraction would revert on insufficient balance
self.balanceOf[msg.sender] -= _value
self.balanceOf[_to] += _value
log.Transfer(msg.sender, _to, _value)
return True
CurveToken.transferFrom
¶
CurveToken.transferFrom(_from: address, _to: address, _value: uint256) → bool
Transfer tokens from one address to another. msg.sender
does the transfer on behalf of the _from
address, and requires sufficient spending allowance. Returns True
if transfer succeeds.
Input | Type | Description |
---|---|---|
_from | address | Address which msg.sender want to send tokens from |
_to | address | Address which msg.sender want to transfer to |
_value | uint256 | Amount of tokens to be transferred |
Emits: Transfer
Source code
@public
def transferFrom(_from : address, _to : address, _value : uint256) -> bool:
"""
@dev 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.
@param _from address The address which you want to send tokens from
@param _to address The address which you want to transfer to
@param _value uint256 the amount of tokens to be transferred
"""
# NOTE: vyper does not allow underflows
# so the following subtraction would revert on insufficient balance
self.balanceOf[_from] -= _value
self.balanceOf[_to] += _value
if msg.sender != self.minter: # minter is allowed to transfer anything
# NOTE: vyper does not allow underflows
# so the following subtraction would revert on insufficient allowance
self.allowances[_from][msg.sender] -= _value
log.Transfer(_from, _to, _value)
return True
Note
While this function emits a Transfer event, this is not required as per the specification, and other compliant implementations may not emit the event.
CurveToken.approve
¶
CurveToken.approve(_spender: address, _value: uint256) → bool
Approve the passed address to spend the specified amount of tokens on behalf of msg.sender
. Returns True
on successful approvals.
Input | Type | Description |
---|---|---|
_spender | address | Address which will spend the funds |
_value | uint256 | Amount of tokens to be spent |
Emits: Approval
Source code
@public
def approve(_spender : address, _value : uint256) -> bool:
"""
@dev 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:
https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
@param _spender The address which will spend the funds.
@param _value The amount of tokens to be spent.
"""
assert _value == 0 or self.allowances[msg.sender][_spender] == 0
self.allowances[msg.sender][_spender] = _value
log.Approval(msg.sender, _spender, _value)
return True
Warning
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).
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).
Note
For Curve Token V1, the minter
attribute is not public
.
CurveToken.mint
¶
CurveToken.mint(_to: address, _value: uint256)
This encapsulates the modification of balances such that the proper events are emitted.
Input | Type | Description |
---|---|---|
_to | address | Address that will receive the minted tokens |
_value | uint256 | Amount of tokens that will be minted |
Emits: Transfer
Source code
@public
def mint(_to: address, _value: uint256):
"""
@dev Mint an amount of the token and assigns it to an account.
This encapsulates the modification of balances such that the
proper events are emitted.
@param _to The account that will receive the created tokens.
@param _value The amount that will be created.
"""
assert msg.sender == self.minter
assert _to != ZERO_ADDRESS
self.total_supply += _value
self.balanceOf[_to] += _value
log.Transfer(ZERO_ADDRESS, _to, _value)
CurveToken.burn
¶
CurveToken.burn(_value: uint256)
Burn an amount of the token of msg.sender
.
Input | Type | Description |
---|---|---|
_value | uint256 | Token amount that will be burned |
Emits: Transfer
Source code
@private
def _burn(_to: address, _value: uint256):
"""
@dev Internal function that burns an amount of the token of a given
account.
@param _to The account whose tokens will be burned.
@param _value The amount that will be burned.
"""
assert _to != ZERO_ADDRESS
self.total_supply -= _value
self.balanceOf[_to] -= _value
log.Transfer(_to, ZERO_ADDRESS, _value)
@public
def burn(_value: uint256):
"""
@dev Burn an amount of the token of msg.sender.
@param _value The amount that will be burned.
"""
assert msg.sender == self.minter, "Only minter is allowed to burn"
self._burn(msg.sender, _value)
CurveToken.burnFrom
¶
CurveToken.burnFrom(_to: address, _value: uint256)
Burn an amount of the token from a given account.
Input | Type | Description |
---|---|---|
_to | address | Account whose tokens will be burned |
_value | uint256 | Token amount that will be burned |
Emits: Transfer
Source code
@private
def _burn(_to: address, _value: uint256):
"""
@dev Internal function that burns an amount of the token of a given
account.
@param _to The account whose tokens will be burned.
@param _value The amount that will be burned.
"""
assert _to != ZERO_ADDRESS
self.total_supply -= _value
self.balanceOf[_to] -= _value
log.Transfer(_to, ZERO_ADDRESS, _value)
@public
def burnFrom(_to: address, _value: uint256):
"""
@dev Burn an amount of the token from a given account.
@param _to The account whose tokens will be burned.
@param _value The amount that will be burned.
"""
assert msg.sender == self.minter, "Only minter is allowed to burn"
self._burn(_to, _value)