Questions tagged [constructor]
The constructor tag has no usage guidance.
98
questions
0
votes
1answer
15 views
When can you use this in a constructor?
I am going through the solidity docs and I have seen that:
// Functions can
// be accessed directly or through `this.f`,
// but the latter provides an external view
// to the function. ...
1
vote
0answers
21 views
Creating Initial ERC721 Tokens Programmatically
I'm interested in minting 100 unique tokens in the constructor of a smart contract, but I'm having an issue where the minting function hasn't been defined yet while the constructor runs. Do I have to ...
2
votes
2answers
41 views
How to get the actual runtime bytecode from creation bytecode and constructor arguments without deploying
Possible outputs of the Solidity compiler include creation bytecode and deployed (runtime) bytecode. However, this compiled deployed bytecode might not be the same as the one that will actually be ...
0
votes
1answer
16 views
Deposit Money Automatically On Child Creation In Factory Pattern
I am implementing a factory pattern contract and on my constructor I want to deposit money into my child contract as soon as the child is rendered
--Factory--
function newChild() {
Child child = ...
0
votes
1answer
22 views
Push large number of items in mapping with constructor or other methods
I would like to push large number of items into mapping. Prototype looks like this
mapping (uint => string) ipfs_hashes;
constructor() ERC721("GameItem", "ITM") public {
...
0
votes
1answer
37 views
Pass mapping as constructor parameter
I'd like to save the contract addresses from DAI and UNI into a mapping when calling the smart contract constructor depending on the network. Below is a minimalistic example that works fine:
contract ...
1
vote
1answer
96 views
Using inherited constructor in Solidity >=0.5.0
I want to use a contract inherit from another contract and use the parent constructor after using another commands in inherited constructor. So I wrote:
pragma solidity ^0.5.10;
contract A {
...
0
votes
1answer
113 views
Cannot figure out how to set constructors and ABI for a contract
So I've been breaking my head over this for the last 2 days. I cannot seem to figure out how to get the constructors and ABI set up properly.
I'm testing smart contracts by copying Sushi contract from ...
1
vote
0answers
15 views
How to enable constructors in the new REMIX IDE or Truffle framework since MIST is depreciated
I used to dabble with making tokens and contracts and started to get back into it.
I liked the functionality that mist offered where you could input constructors values directly in mist. I can not ...
0
votes
1answer
31 views
Truffle cant deploy contract with reverting constructor
I'm developing a dapp with the truffle suite and now I'm running into a problem.
Everything is working locally in the ganache instance.
My contract should disallow direct payments to the contract, so ...
0
votes
1answer
20 views
How much Ether does a Smart Contract Address hold before a Payable Instantiation?
The following code always reverts to "Contract must be empty".
But shouldn't address(this).balance == 0 if the contract hasn't even been instantiated yet?
Maybe since the contract doesn't ...
0
votes
1answer
49 views
Can someone read this private variable?
my purpose is to generate a random key when the smart contract is created and save that key in a private variable. I don't what to know its value either.
Let's take for example the code below:
pragma ...
1
vote
1answer
55 views
What happens when a Contract is added to the genesis block?
Recently I found out that you can add smart-contracts to the genesis block (genesis.json) of your local ethereum network.
Since normally, when you add a smart-contract via a transaction, you can call ...
0
votes
0answers
81 views
How to listen for contract creation, or all block events?
I'm building a web app with web3 where users can deploy a certain contract and assign some people to it. Inside the constructor of that contract I also output a certain event. I want these assigned ...
3
votes
0answers
169 views
Passing constructor arguments from child contract to parent contract
The ERC721 standard contract requires a token name and symbol in its constructor. I have inheritance pattern that looks likes Contract A is B and Contract B is ERC721.
If I want to set my token name ...
2
votes
1answer
202 views
How do I set the constructor arguments when deploying using OpenZeppelin CLI?
My Token contract compiles fine using solidity 0.5.0:
import "/Users/lennard/Desktop/GGToken/node_modules/@openzeppelin/contracts/token/ERC20/ERC20Detailed.sol";
import "/Users/lennard/Desktop/...
2
votes
1answer
31 views
can a hacker call constructor() function after deploy if it is public? [duplicate]
Is below function can be called by a hacker after deploy
constructor() public
{
test = true;
}
2
votes
1answer
1k views
Error: This contract may be abstract
My solidity contract compiles in Remix, but when I try to deploy it it fails and throws
Error: This contract may be abstract, not implement an abstract parent's methods completely or not invoke an ...
0
votes
1answer
25 views
Trouble deploying one contract from another
Why creating a contract new RewardCourts() in another contract takes more than ten kilobytes of bytecode in the contract it is called from? (It makes bytecode too big and I can't deploy it!)
What to ...
1
vote
1answer
42 views
Payable constructor gives revert message
I am trying to execute the following contract on remixe IDE:
pragma solidity ^0.5.4;
contract GuessTheNumberChallenge {
constructor() public payable {
require(msg.value == 1 ether);
}
...
2
votes
3answers
639 views
Passing constructor arguments to the CREATE assembly instruction in solidity
I have a contract which deploys other contracts by bytecode:
contract DeployContract {
function deploy(bytes calldata _bytecode) external returns(address addr) {
bytes memory bytecode = ...
1
vote
1answer
102 views
How to share TypeScript code between truffle tests?
I have some code in my TypeScript tests, say:
function foo() {
return 'bar';
}
which I'd like to share with all my tests. The simple solution is to copy the function into each *_test.ts file.
...
1
vote
1answer
34 views
Error: invalid address in solidity constructor
I get a huge error message (~1MB) starting with
Error: invalid address (arg="_readAccess", coderType="address", value={"constructor":{"contractName":"SenderAccess","abi":[...
when executing a test ...
0
votes
1answer
61 views
Stack too deep problem
I try to add more property to the scenario struct but when I run the compile the same error appear:
struct Scenario {
uint id;
address payable author;
address editor;
...
1
vote
1answer
168 views
Can you emit events in a contract constructor?
I have a constructor that is emitting an event, but cannot seem to see/catch/filter that event after deployment.
1
vote
2answers
327 views
Remix: 0x0 Transaction mined but execution failed due to construction
I have the following example smart contract, where I cannot deploy using remix into my private network using environment Web3 provider. The error I am getting is Transaction mined but execution failed ...
0
votes
1answer
443 views
Uncaught TypeError: web3.eth.Contract is not a constructor
For whatever reason, when I attempt to set an instance of a contract in a javascript file, I get the following message in my console:
Uncaught TypeError: web3.eth.Contract is not a constructor
At ...
0
votes
1answer
212 views
Storing geo location in contract
I am beginner in solidity programming, I am trying to write my first contract. I am trying to store a piece of land (which is array of coordinates) against a person. I am having trouble storing the ...
0
votes
1answer
206 views
passing variables between different contract by solidity (0.5.0+ version)
I writed ERC20 contract and ICO contract for a test , but I meet a lot problem with compile problem.
My ERC20 contract have own constructor
but,I also need a ICO contract(a control)for passing ...
0
votes
0answers
18 views
Unexpected behaviour. Huge size increase when adding new SubContract()
I have a contract similar to:
contract Contract01 {
SubContract _refContract;
...
constructor() public {
refContract = new SubContract();
}
function setSubContractRef(SubContract ...
1
vote
1answer
327 views
How to pass arguments to token smart contract generator?
I'm trying to build a 'token generator' smart contract that accepts 3 arguments to then deploy a new token smart contract with those inputs ('strings' for symbol, name, 'address' for owner). I am a ...
0
votes
1answer
16 views
Function inside constructor is called from which address?
interface token {
function transferFrom(address _from, address _to, uint256 _value) external returns (bool success);}
contract CampaignFactory{ token public token_instance;
constructor()...
1
vote
1answer
266 views
Solidity : Error when pushing an address into a dynamic address type array
I'm trying to insert an address into an address type dynamic array. It works well when I do the operation inside a function. There are no errors and the elements are properly pushed into the array.
...
3
votes
3answers
296 views
Is a constructor needed to set a contract owner?
until now I have set the owner in a contract like so:
pragma solidity ^0.5.2;
contract SampleContract{
address payable owner = msg.sender;
}
in the docs it is suggested to do it this way:
...
1
vote
2answers
1k views
Contract deployment using web3.eth.contract(abi) with constructor arguments
I'm trying to deploy the following smart contract:
pragma solidity ^0.5.00;
contract TestContract {
address public owner;
string public word;
constructor(string memory _word) public{
...
1
vote
2answers
427 views
Encode constructor arguments used when deploying a contract
How can I encode the constructor arguments when deploying a contract?
Here is my deployment function:
async function deploy(abi, bin, args) {
let contract = new this.web3.eth.Contract(JSON.parse(...
1
vote
1answer
268 views
What does etherscan mean by “Constructor Arguments (ABI-Encoded and is the last bytes of the Contract Creation Code above)”?
I'm inspecting a contract on etherscan, at the following URL:
https://etherscan.io/address/0x5cb5f46a655c02889172323760d12d0e5d83cdaf#code
At the bottom of the web-page, I see two sections:
...
1
vote
1answer
294 views
How can I retrieve the constructor arguments used during contract deployment
I know how to extract the constructor arguments out of the transaction object returned from a contract-deployment operation.
It is explain in web3.js official documentation here.
But this is not an ...
0
votes
1answer
259 views
Making a contract with new keyword address is always 0x0000000000000000000000000000000000000000
I'm making a contract that makes other contracts. Once the contract is made using address tokenAddress = new MyToken('Name'); I want to save the address of the contract, tokenAddress, in MyStruct. ...
2
votes
1answer
284 views
Solidity Constructor Parameter List
Which variables types are accepted by a constructor in Solidity? In particular, is it possible to pass an actual contract as an constructor input? For example:
contract ContractA {
constructor (...
0
votes
1answer
45 views
Constructor Function: How can I tell which function is the constructor?
How can I tell which function is the constructor function?
In the OpenZeppelin implementation of the MultisigWallet, OpenZeppelin claims this is the constructor function:
/**
* Constructor, sets ...
1
vote
1answer
61 views
Solidity Syntax question
What happens if a function is being passed before { into another function?
Like DetailedERC20(_name, _symbol, TOKEN_DECIMALS) in this example:
function MyToken(Registry _registry, string _name, ...
2
votes
1answer
167 views
Getting and storing address of erc20 contract after dynamically creating it
I have a function which dynamically creates an ERC20 contract on calling a function in another contract as follows:
function createDao(string _tokenName) public payable {
tokenNumberIndex = ...
2
votes
1answer
374 views
How does a contract's constructor work and load input values?
I set up the following contract:
pragma solidity ^0.4.25;
contract Simplest {
uint x;
constructor(bool _lucky) public {
if (_lucky == true) {
x = 7;
} else {
...
1
vote
1answer
108 views
problem with constructor parameter in rawtransaction
I am using remix and ganache to test out my contract. The contract deploys successfully, however, I do not see the state variables initialized with the constructor parameters when I look at the ...
1
vote
0answers
113 views
the constructor should be payable if you send
I have been testing the code and for some reason I am having a block. The error is described as "the constructor should be payable if you send value". The debugger points to " uint256 weiAmount = ...
0
votes
1answer
72 views
Smart Contract Testing
I am writing test driven smart contracts. There is one smart contract with parameterized constructor. And I am using the require statement in the constructor. I want to catch the error in my test ...
0
votes
1answer
71 views
When extending a contract how to call the external constructor and pass parameters?
I have the following contract
import "zeppelin-solidity/contracts/token/ERC721/ERC721Token.sol";
contract Contract is ERC721Token {
function Contract(string _name, string _symbol) public {
...
4
votes
1answer
200 views
Purpose of the function with the contract's name?
What is the purpose of the WithdrawalContract function in this case? If becomeRichest doing exactly same but with a certain condition and adding a pending withdrawal to the pendingWithdrawals.
0
votes
1answer
476 views
Deploying a contract with a “payable” constructor and including input parameters?
There is a useful Solidity contract HERE. However, there are two things at time of its deployment:
(1) The first thing is the contract balance since its constructor is payable.
(2) And the second ...
