This contract is a decentralized exchange (DEX) for swapping between ETH and a specified ERC20 token (Balloons). It allows users to provide liquidity, earning liquidity provider tokens (LPTs) in return, and to swap tokens. It includes functions for initializing liquidity, pricing assets, adding/removing liquidity, and executing token swaps.
DEX :
We want to create an automatic market where our contract will hold reserves of both ETH and 🎈 Balloons. These reserves will provide liquidity that allows anyone to swap between the assets. NOTE: functions outlined here are what work with the front end of this branch/repo. Also return variable names that may need to be specified exactly may be referenced (if you are confused, see solutions folder in this repo and/or cross reference with front-end code).
price(uint256,uint256,uint256) :
Follow along with the [original tutorial](https://medium.com/@austin_48503/%EF%B8%8F-minimum-viable-exchange-d84f30bd0c90) Price section for an understanding of the DEX's pricing model and for a price function to add to your contract. You may need to update the Solidity syntax (e.g. use + instead of .add, * instead of .mul, etc). Deploy when you are done.
IERC20 :
Interface of the ERC20 standard as defined in the EIP.
Approval(address,address,uint256) :
Emitted when the allowance of a `spender` for an `owner` is set by a call to {approve}. `value` is the new allowance.
Transfer(address,address,uint256) :
Emitted when `value` tokens are moved from one account (`from`) to another (`to`). Note that `value` may be zero.
allowance(address,address) :
Returns the remaining number of tokens that `spender` will be allowed to spend on behalf of `owner` through {transferFrom}. This is zero by default. This value changes when {approve} or {transferFrom} are called.
approve(address,uint256) :
Sets `amount` as the allowance of `spender` over the caller's tokens. Returns a boolean value indicating whether the operation succeeded. IMPORTANT: 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 Emits an {Approval} event.
balanceOf(address) :
Returns the amount of tokens owned by `account`.
totalSupply() :
Returns the amount of tokens in existence.
transfer(address,uint256) :
Moves `amount` tokens from the caller's account to `to`. Returns a boolean value indicating whether the operation succeeded. Emits a {Transfer} event.
transferFrom(address,address,uint256) :
Moves `amount` tokens from `from` to `to` using the allowance mechanism. `amount` is then deducted from the caller's allowance. Returns a boolean value indicating whether the operation succeeded. Emits a {Transfer} event.
SafeMath :
Wrappers over Solidity's arithmetic operations. NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler now has built in overflow checking.
This contract is a decentralized exchange (DEX) for swapping between ETH and a specified ERC20 token (Balloons). It allows users to provide liquidity, earning liquidity provider tokens (LPTs) in return, and to swap tokens. It includes functions for initializing liquidity, pricing assets, adding/removing liquidity, and executing token swaps.
DEX :
We want to create an automatic market where our contract will hold reserves of both ETH and 🎈 Balloons. These reserves will provide liquidity that allows anyone to swap between the assets. NOTE: functions outlined here are what work with the front end of this branch/repo. Also return variable names that may need to be specified exactly may be referenced (if you are confused, see solutions folder in this repo and/or cross reference with front-end code).
price(uint256,uint256,uint256) :
Follow along with the [original tutorial](https://medium.com/@austin_48503/%EF%B8%8F-minimum-viable-exchange-d84f30bd0c90) Price section for an understanding of the DEX's pricing model and for a price function to add to your contract. You may need to update the Solidity syntax (e.g. use + instead of .add, * instead of .mul, etc). Deploy when you are done.
IERC20 :
Interface of the ERC20 standard as defined in the EIP.
Approval(address,address,uint256) :
Emitted when the allowance of a `spender` for an `owner` is set by a call to {approve}. `value` is the new allowance.
Transfer(address,address,uint256) :
Emitted when `value` tokens are moved from one account (`from`) to another (`to`). Note that `value` may be zero.
allowance(address,address) :
Returns the remaining number of tokens that `spender` will be allowed to spend on behalf of `owner` through {transferFrom}. This is zero by default. This value changes when {approve} or {transferFrom} are called.
approve(address,uint256) :
Sets `amount` as the allowance of `spender` over the caller's tokens. Returns a boolean value indicating whether the operation succeeded. IMPORTANT: 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 Emits an {Approval} event.
balanceOf(address) :
Returns the amount of tokens owned by `account`.
totalSupply() :
Returns the amount of tokens in existence.
transfer(address,uint256) :
Moves `amount` tokens from the caller's account to `to`. Returns a boolean value indicating whether the operation succeeded. Emits a {Transfer} event.
transferFrom(address,address,uint256) :
Moves `amount` tokens from `from` to `to` using the allowance mechanism. `amount` is then deducted from the caller's allowance. Returns a boolean value indicating whether the operation succeeded. Emits a {Transfer} event.
SafeMath :
Wrappers over Solidity's arithmetic operations. NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler now has built in overflow checking.
Single_Pool_DEX
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