Questions tagged [interfaces]

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Migrate dapp from Tron to Ethereum [closed]

I have a dapp that was developed on Tron a while ago. I would like to move the dapp to the Ethereum network, so I modified and deployed the new smart contract. Now I need to modify the UI in the way ...
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ERC-2222 : Funds Distribution Token implementation for a fee contract

My MainCore contract is a contract who sell NFT, and all the sell and buy have a 1% fee for team developper (uint DevelopperCutTotalSupply). I try to implement the ERC-2222 "Funds Distribution ...
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1answer
17 views

TxOriginVictim(msg.sender).transferTo(owner, msg.sender.balance): What is the purpose of Interface and what is TxOriginVictim(msg.sender)?

I have two contracts in the context of tx.origin Vulnerability: pragma solidity ^0.5.8; contract TxOriginVictim { address owner; constructor() public{ owner = msg.sender; } ...
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12 views

How this snippet is linking contracts? How each contract finds the other

I'm trying to understand how can two contracts be deployed and interact with each other, given that I don't have their addresses before deployment. I ended in this question and I don't understand the ...
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1answer
24 views

Why use the Interface (IERC20), instead of the implementation contract (ERC20)?

I'm playing with a contract that uses an ERC20 token, and I can see basically 2 options to init the token: Use the interface contract (IERC20) Use the implemented contract (ERC20) Interface version: ...
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1answer
54 views

Reflect Base contract's update in another contract

I have wanted to know what concept is it called when we want two contracts which are deployed on the Network, reflect the transaction and updates in another contract. for example: contract Base{ ...
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3answers
48 views

Do view functions cause reentrancy vulnerabulity?

It's well known that calling an external function before changing something in the contract causes a security problem called "reentrancy vulnerability". Does calling an external function ...
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16 views

How to use web3 when one smart contract is interfacing with another?

A few months back I posted this question on this form. Since then, I've used the interface method to make my smart contracts interact together. I didn't have any problem while testing and developing ...
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27 views

how to pass fix size array via interface in solidity 0.4.25

I used the following code interface test{ function testfunction(uint[20] memory P, uint[20] memory Q) external returns(uint,bool,uint); } It gives the error Location has to be calldata for external ...
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1answer
19 views

In interface does the function listed have to be exactly the same as they are in contract?

In solidity 0.7.x, I am creating an interface of contract A in contract B to allow contract B call functions in contract A. contract A { function transfer(address recipient, uint256 amount) public ...
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2answers
41 views

remote contract function call with solidity

I've deployed this very simple Contract: contract Contract1 { function myfunction(uint param1) public returns (uint) { return param1+1; } } Now, I've deployed a second contract: ...
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1answer
43 views

Is it possible to call a public array from another contract?

Let's say there is a uint[] public MyArray declared in contract_A. Is there a possiblility to create an interface contract_A that would allow to read the values in MyArray from another contract, or ...
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2answers
258 views

Can't override ERC20 Methods

I try to override ERC20 methods ... The doc says it should be possible but I get the error: CompileError: @openzeppelin/contracts/token/ERC20/ERC20.sol:96:5: TypeError: Trying to override non-virtual ...
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1answer
91 views

ERC20 Interface

When you make a token, must you have an ERC20 Interface (such as the one below)? What is the purpose of it? pragma solidity 0.6.6; /// @notice ERC20 https://eips.ethereum.org/EIPS/eip-20 with ...
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95 views

Wrapping functions in interfaces to enable higher order function capability in Solidity?

Let's say I want to have higher order function capabilities in my Solidity Dapp. Also I want to be able to pass in new functions as input to higher order functions contained within contracts that were ...
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1answer
96 views

Uncaught TypeError: TheContract.at is not a function

just trying my first steps in ethereum and web3. So i found this tutorial: https://www.youtube.com/watch?v=hcTPjpPvas8 But it raise an error: index.html:85 Uncaught TypeError: TheContract.at is not a ...
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1answer
368 views

How to call “payable function” via interface in solidity [duplicate]

I have a function marked as payable in contract A and I want to call it from contract B so that msg.value in contract A can have its desired value and contract A must have balance of sent amount , how ...
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1answer
207 views

How to properly define an interface in Solidity 0.6?

One of the breaking changes of solidity 0.5 was making explicit function visibility mandatory, hence all interface functions must be defined as external today. In solidity 0.6, there seems to be two ...
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1answer
42 views

How to deploy smart contract so that average user can interact with its public functions?

I sucesfully wrote and deployed smart contract using Remix and Metask to generate hashes used as keys. This contract has few payable public functions that set or get some numbers. After deploying ...
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1answer
34 views

Like an ERC20 interface, do we have any interface or a smart contract that supports creating and transferring Ether on Ethereum?

To create a token on Ethereum, we use ERC20 token interface to design our token smart contract that captures functions required like mint(), tranfer(), balanceOf(), etc. Similarly, do we have any ...
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1answer
117 views

Buy tokens form other smart contract using interface

I have two separate contracts, let's say Token and BuyFrom. pragma solidity >=0.4.22 <0.7.0; interface InterfaceToken { function invest(address contributor) external payable; } contract ...
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35 views

is there any possibility to read struct via interface from deployed contract?

the contract is deployed which has no view function for that particular struct, is there any way to read values via interface in another contract which I want to write and deploy ?
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1answer
117 views

What is the use of a interface or function without implementation?

Take, for example, this code. The interface contains function without implementation, so how it's useful. pragma solidity ^0.5.0; interface Calculator { function getResult() external view returns(...
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2answers
46 views

What does it mean to declare an item of type contract?

Wasn't quite sure how to word the title, but in the following code: contract KittyInterface { ... } contract ZombieFeeding is ZombieFactory { KittyInterface kittyContract; } what is the ...
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2answers
55 views

How bad is it to change a function inside ERC721 interface?

I'm creating a NFT and I want the transferFrom function to be payable. In order to do so I need to edit the ERC721 interface and make that function payable also there. If I do so everything compiles ...
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1answer
58 views

What does mutability guarantees mean in erc721

Some functions from ERC-721 interface contain payable modifiers. function transferFrom(address _from, address _to, uint256 _tokenId) external payable; I was wondering why it is payable and found ...
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39 views

Nested usage of interfaces?

Using solidity ^4.x, it seems I can use an interface as a parameter type in a function from a different interface. Example: interface IERC20 { function transfer() external; } import "./IERC20....
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4k views

File import callback not supported import “./IERC20.sol”;

when I try to compile my contract I see errors like this : DemirelToken.sol https://eksiup.com/p/4z49413damc3 here's the code : pragma solidity ^0.5.0; import "node_modules/openzeppelin-...
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1answer
451 views

ERC721: Interface ID Registration

Why we need to register Interface ID in ERC721 token. I was just going through the openzeppelin-solidity erc721 code and curious to know that why we need to use this. That interface id register code ...
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1answer
1k views

How to interact with ERC20 interface?

My target is to send from the ERC20Wrapper.sol deployed contract BAT tokens to my hard coded address. I've created ERC20 Interface: pragma solidity 0.4.18; interface ERC20 { function ...
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1answer
55 views

DAPP WALLET transaction always fails

To improve my skills in solidity I'm working on a "wallet dapp". Based on smart contracts only, users can send ERC20 to another wallet. It works like that: user gives the following parameters: ...
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1answer
402 views

Solidity, how to cast SmartContract type to address

I am currently a bit stuck with my contract, the issue is following: I define a smartcontract type which is used for another address (aka address is smartcontract that provides the specified interface)...
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3answers
224 views

REMIX:This contract does not implement all functions and thus cannot be created

What should I do? pragma solidity ^0.4.21; contract ScoreInterface { function hit() public; function score() public view returns (uint); } This contract does not implement all ...
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2answers
316 views

Solidity how to check if user is already used another contract?

I am trying to figure out how to set up a simple communication between contracts. For example, we have a contract Passport, in which the user writes his data. After that, through the Election ...
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1answer
23 views

In case we have an interface written in a seperate .sol file how do we migrate it successfully?

HI consider i have 3 smart contracts A,B,C. I have a separate file D.sol which is an interface used in all A,B and C. What would the migration script look like for this project?
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234 views

Can I extend the interface of a contract without redeploying it?

The case I'm dealing with is a contract which should serve as a Data Abstraction Layer. So ideally, it should provide only getter functions and setter functions. For example, my interface is: ...
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1answer
113 views

how to parse values returned by one contract into another?

I've two contracts deployed one is UserRegistration and another is Exam I've getUser(uint id) method to fetch data of particular user using users mapping, function getUser(uint _id) public constant ...
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1answer
187 views

Can abstract contracts in solidity have state variables?

I want to have one deployed contract with my data structure and all data and another separate contract with functions that calls the deployed contract. If i've understood things correctly, one should ...
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1answer
196 views

Enum in interfaces

Following the documentation I try to add a enum to my interface. Inside the interface I have a method called get that returns one of the enum value. Im trying to add the enum to the interface, because ...
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1answer
113 views

Interfaces implementation visibility

I have this interface: pragma solidity ^0.4.24; interface EventsInterface { function removeValueFromArray(uint _userId, uint[] array) external returns(uint[]); } And this contract: pragma ...
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1answer
141 views

Interface overriding

I have two contracts. One of them inherits another. Inside the parent contract I have the interface interface Token { function transfer(address to, uint256 value) external returns (bool); } I ...
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1answer
2k views

Interfaces in solidity

I have one interface like the following: pragma solidity ^0.4.11; interface TokenInterface { function transfer(address recipient, uint amount) external returns(bool); } And the implementation in ...
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2answers
496 views

Variables in interfaces

Im trying to implement my first interface. But when I try to add a new variable, Remix tell me that can´t add variables in interfaces. It have sense to set the fixed variables that the extended ...
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1answer
47 views

Simple but important question: How to get the value of contract's state when using Metamask? [closed]

I'm designing an HTML file (or a user interface: UI) for my smart contract. let's assume that my contract has a state as follows: address public owner;// it is set to "...
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77 views

Why is not Metamask invoked in my user interface?

I'm running a private Ethereum blockchain on my computer. I've installed Metamask on my chrome as well. I can create an account on metamask, and then interact with my smart contract deployed on my ...
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1answer
87 views

Error in external function parameter defination for an interface

Dear community members, I have come across an error while defining an interface (just using the standard one interface ERC721TokenReceiver) this interface is mentioned in this link https://github....
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2answers
40 views

Is it possible to have an optional property or method in an interface?

I currently can't deploy any contract which doesn't adhere 100% to the specified interface(s). Is there a way to mark some properties or methods as optional and, if not, is this a planned feature?
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2answers
216 views

Why are all parameters prepended by an underscore in ERC interfaces? [duplicate]

For instance, both ERC-721 and ERC-725 have underscores(_) before any function parameter. I understand that normally their goal is to avoid variable overloading. However, what is the rationale for ...
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1answer
73 views

Contract Using An Interface Is Not Compiling

I am learning Solidity and I am using Remix to experiment and enhance my learning. I am currently trying to create a simple contract that uses an Interface. pragma solidity ^0.4.19; contract ...
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2answers
960 views

How to create Interface to read Struct in mapping?

There are 2 contracts A and B. A has a mapping which returns Struct: mapping (bytes32 => Cup) public cups; How can we read the cups mapping in contract B? Following code doesn't work for sure:...