Questions tagged [interfaces]

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2answers
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Can we modify ERC20 functions?

I have to create and transfer token using ERC 20.Inside the standard interface of ERC 20, we have function approve(address spender,using token) which inturn approves spender to take some token from (...
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0answers
14 views

what do I do with compiled interface output?

I created a token sale smart contract. And it has an interface that resolves to a token contract address. Now the output folder has the compiled token sale smart json file and the interface json file....
1
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1answer
311 views

creating and array using type Big.Int and counting the sum of all integers inside it

Im communicating with a smart contract trying to get the balances from a list of addresses. I then want to get the sum of all balances but I am stuck on actually creating the array to store all the ...
1
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1answer
335 views

Smart Contract Design: Escrow/Controller contract

How would I go about creating follow: Escrow/Controller contract A which is capable of accepting ERC20tokens from contract B, and ETH from party C and do a swap when certain conditions are met. This ...
2
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2answers
253 views

ERC20 Interfaces overwriting ERC721 functions - Possible to adhere to standard?

Is it possible to have a contract that both generates and manages its own NFT according to the ERC721 Standard, and is able to make calls to outside ERC20 contracts? My contract currently inherits the ...
1
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1answer
807 views

What are the benefits of abstract contracts?

I've seen similar questions, but none answer why people use abstract contracts. I come from a non-OOP JavaScript background, so I have some trouble understanding these things. From the docs: pragma ...
3
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1answer
363 views

Ethereum address URL

Is there a standard or a convention for URLs of Ethereum address? That is I want clicking xxx://0x... to initiate transfer to this account.
3
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1answer
733 views

Why public variables aren't able to implement interface functions?

I'm curious why interfaces don't accept public variables as implementations, since public variables have getter functions generated for them. For example why couldn't the ERC20 balanceOf interface ...
2
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1answer
116 views

Why standard tokens inherit interface?

I was wondering why most tokens inherit from an ERC20 interface, instead of just implementing all the functions directly. Are there are any problems that arise if the interface functions are just ...
3
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2answers
561 views

ERC-721 safeTransferFrom is overloaded?

According to ERC-721 interface the function safeTransferFrom seems to be overloaded: function safeTransferFrom(address _from, address _to, uint256 _tokenId) public; function safeTransferFrom(address ...
1
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3answers
279 views

How to detect if a contract has a particular function implemented?

I would like to detect if an address has a particular function implemented. In this case isSafe: interface ISafe { function isSafe() public pure returns (bool _true); // other functions I ...
2
votes
2answers
625 views

Anyone knows what does this contract code mean?

Refer to the link below: https://github.com/bokkypoobah/Tokens/blob/master/contracts/MyToken.sol Line 62: contract ApproveAndCallFallBack { function receiveApproval(address from, uint256 tokens,...
1
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0answers
52 views

Enum type in interface function declaration

I understand that you "cannot define enums" in an interface contract; but, in the contract that I am working with, some of the function declarations require an enum type as an input or output ...
2
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1answer
690 views

Solidity function overloading and selectors — member not unique

I have the following contract: pragma solidity ^0.4.17; contract test{ mapping(bytes4 => bool) internal supportedInterfaces; uint public a; function test() public{ supportedInterfaces[...
0
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1answer
155 views

Identical contract functions in interface with different inputs

In the ERC721 interface, you have two functions with the same name: function transferFrom(address _from, address _to, uint256 _tokenId) public; function transferFrom(address _from, address _to, ...
2
votes
1answer
659 views

How do I check in solidity if interface is supported?

In the new ERC721 documents (erc721.org), the interface says that one of the functions should be: /** * @dev Returns `true` if the contract implements `interfaceID` and`interfaceID` ...
4
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2answers
457 views

Interface initiailization

I'm following cryptozombies solidity tutorial. In lesson 2, chapter 11 it explains how to create an interface for CryptoKitties as follows: contract KittyInterface { function getKitty(uint256 _id) ...
2
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1answer
616 views

How does the ERC20 tutorial instantiate an unimplemented interface?

I've been going through the official Ethereum token tutorial and I noticed that the provided token code includes the following lines within the approveAndCall function: tokenRecipient spender = ...
0
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1answer
881 views

how to call one contract function into another contract

contract xyz { mapping(address => bool) Users; function add(address userAddress) { require(userAddress != 0x0 && !Users[userAddress]); Users[...
0
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1answer
99 views

Specify full ABI of another contract?

Contract A calls contract B. Does contract A need to know B's full ABI for its external functions? Or can you just give it the interface for the functions that contract A will call.
1
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1answer
798 views

Very simply: setProvider is not a function

I have a very simple contract already deployed to the kovan network I want to create a very simple web3 interface, so I'm following the truffle webpack metacoin example with the following app.js ...
4
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1answer
1k views

(Sub) contract vs. library vs. struct vs. Interface

First I googled and read through these questions: Creating multiple contracts or Single contract with struct Child contract vs struct Why are so many examples using separated contracts (e.g. crowed ...
1
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1answer
684 views

Array of interfaces of contracts

In an oop language, I could do the following: I can define an interface Foo with a function F(). I then define two classes Bar1 and Bar2 implementing this interface. I can then create an array of Foo ...
5
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1answer
6k views

Deploying abstract contracts and interfaces

I am trying to create a basic inheritance hierarchy with abstract/virtual formalisms. Consider the following two contracts: Abstract Contract (IUser.sol): contract IUser { function addUser (...
3
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1answer
262 views

Best practices for interacting with other contracts

I would like to know what is the best approach and the best practices to intercat with other contracts. Here are the MyFriendToken.sol and the MyService.sol: MyFriendToken.sol I would like to know ...
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0answers
52 views

What's so special about the .call() function?

All that the docs have to say about it is that it "lets the Ethereum network know we're not intending to persist any changes." So I get that it's used when not conducting a transaction. So, I decided ...
1
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0answers
256 views

ipcapi parameter usage

I initialize a node on my private test net passing only the eth interface in the ipcapi parameter expecting that I won't have access in the other interfaces such as admin etc.. However, when I attach ...
1
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1answer
293 views

Does an API standard for price feeds exist?

The ERC 20 defines a standard interface for designing a token contract. Does a similar standard exist for defining feeds that can be called by other contracts?
4
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1answer
1k views

Does a Solidity Interface Contract need to implement all functions, or only the function subset used in the contract that implements the interface?

Let's assume the following: There is a master contract A, an interface contract IB, and a slave contract B A implements IB to allow upgrading B without redeploying A Question: Does IB need to have ...
7
votes
3answers
9k views

How to call smart contract from html/Javascript

I want to have an html/Javascript code interact with a smart contract. Can someone please outline the basic/high level steps? I am seeing too many things spread across the net, finally confusing.
5
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1answer
3k views

How to get address of contract interface

In the contract below, how to look up address of tokenContract ? Operator != not compatible with types address and contract Token if(msg.sender != tokenContract) throw; contract ...

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