Questions tagged [constructor]
The constructor tag has no usage guidance.
73
questions
1
vote
1answer
20 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
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2answers
64 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
25 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
19 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
47 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
16 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 ...
0
votes
1answer
106 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
8 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
62 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.
...
2
votes
3answers
63 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:
...
0
votes
1answer
441 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
137 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
87 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
62 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
63 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. ...
1
vote
1answer
146 views
Solidity Constructor Parameter List
can someone list the parameter types accepted by a constructor in solidity .. in particular, can we do something like passing an actual contract in a constructor's parameter list, for example:
...
0
votes
1answer
28 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
44 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, ...
1
vote
1answer
98 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
137 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
70 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
88 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
61 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
44 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
148 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
315 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 ...
0
votes
1answer
102 views
Solidity state variable resets to default inside function
For this project, I am coding smart contracts for Ethereum using Solidity.
In the following code, the variable numCertificates should initially be 1. Nonetheless, newCertificateId is 0 when assigned. ...
0
votes
1answer
31 views
Advantage of using a contract contructor with parameters
What is the advantage of using a constructor with parameters instead of hard coding the values? Is there a possibility to reuse a once deployed contract?
0
votes
1answer
306 views
Fixing warning about “constructors” causes new error referencing the old function name [duplicate]
I'm using the solidity code for deploying new ERC20 tokens found here and quoted below:
pragma solidity ^0.4.16;
contract owned {
address public owner;
function owned() public {
...
3
votes
1answer
109 views
v0.4.22 solc compile failing - not predictable behavior
Error:
Warning: Defining constructors as functions with the same name as the contract is deprecated. Use "constructor(...) { ... }" instead.
function CappedCrowdsale(uint256 _cap) public {
^ (...
0
votes
1answer
355 views
address.transfer(value) is throwing error in solidity contract.
I am building an approval contract in Remix and have been stuck on this issue.
When I try to transfer wei using address.transfer(value), it throws an error. I have marked it in the code below.
...
2
votes
0answers
250 views
Passing struct into new contract through constructor
I have a function in my ChangeManager contract which should create multiple ChangeRequests. I tried to model a Change by using a struct and pass this from my ChangeManager to the ChangeRequest:
Code ...
2
votes
1answer
480 views
Can a function with the same name as the contract be declared both as a function and a constructor?
A function with the same name as the contract is normally a constructor and it’s bytecode isn’t included in the resulting contract.
But is there a way to declare a function with the same name as the ...
1
vote
2answers
424 views
Contract inheritance
I really hope this is not a dumb question.
I am trying to call the constructors of the inherited contracts in a structure like this:
contract A{
uint a;
constructor (uint _a) public {
...
1
vote
2answers
108 views
Multiple constructor functions - Will they be executed once?
let's say I have the following contract/solidity file:
pragma solidity ^0.4.20;
contract partOne {
address public owner;
function partOne() public {
owner = msg.sender;
}
}
...
0
votes
2answers
85 views
Correcting Code for Constructor
This StackExchange question ALMOST answered my question. However I don't know how to exactly correct my code so that the function named after the contract is replaced by the constructor.
How ...
1
vote
1answer
336 views
Ethereum Solidity how to deploy a contract from another contract with constructor function
The old way: constructor function is the same as the contract name:
contract CtrtFactory {
function makeCtrt() {
address ctrtAddress = new Ctrt(...);
}
}
contract Ctrt() {
function Ctrt(..) ...
0
votes
1answer
952 views
Using constructor() and the fallback function in the same contract gives error
I'm trying to compile something that mirror a pattern like this and getting the following error from remix:
"browser/ballot.sol:26:3: DeclarationError: Function with same name and arguments defined ...
0
votes
1answer
754 views
Transfer ownership of a contract in the constructor
I'm trying to create a contract, and set its owner at the same time
contract ERC721CrowdSale is Ownable { ... }//contract is in the same file and has access to methods
contract CS_Creator is Ownable{...
0
votes
1answer
616 views
The constructor should be payable if you send value
I have written a contract as follows:
pragma solidity ^0.4.0;
/*
Simple contract that mediates disputes using a trusted arbiter
*/
contract Taxi {
enum State {IDLE, FINDING_DRIVER, ...
1
vote
1answer
754 views
Dynamic Arrays in solidity Structs
I have question about creating Struct where size of array passed to that struct could have different lengths. As in code below I could pass to this Recipe 2 ingredients, 3 ingredients or whatever ...
3
votes
1answer
447 views
Multiple inheritance and order of chaining of multiple base constructors [duplicate]
I am trying to understand the order of invocation of base class constructors in the presence of multiple inheritance. As far as I can tell, the order appears under-specified in the Solidity ...
1
vote
2answers
2k views
Does Solidity support passing an array of strings to a contract's constructor yet?
I am going through a tutorial from 2017 that says it was updated in January of 2018. It says that currently you can not pass an array of strings directly to the constructor of a contract and that you ...
2
votes
0answers
25 views
Why not possible limiting gas but forwarding ether in creating this contract from Solidity documentation
In the Solidity docs Creating contracts via new there is an example:
contract D {
uint x;
function D(uint a) public payable {
x = a;
}
}
and it states in the accompanying text:
...
0
votes
1answer
24 views
Setting mapping value in constructor has no effect?
In the following smart contract:
pragma solidity ^0.4.20;
contract MyCoin {
uint _totalSupply;
mapping(address => uint) public balances;
function MyCoin() public {
_totalSupply = 1;
...
1
vote
1answer
561 views
What is the significance of making constructor payable?
Aren`t constructors used to initialize variable at the time of contract creation? In common patterns section in solidity documentation, payable constructor is used for withdrawal pattern example.
...
1
vote
1answer
266 views
Best way to send an address to the constructor in Remix?
I know how to pass an ETH address to the constructor in truffle. What is the best way to do it in Remix?
Say contract A is in Remix to create Tokens and contract B (another solidity file) is the ...
0
votes
2answers
183 views
Access deployed contract's constructor's parameters from address
I'm using ethers.js but any answer will be okay !
I'm trying to access a contract's constructor's parameters that was used when deployed to make sure the contract has not been modified before being ...
1
vote
1answer
93 views
Why would data be passed into a contract constructor rather than just hardcoding it, which would be less costly?
Doesn't it cost more to pass in variable assignment via a constructor due to changing state?
Wouldn't it be cheaper to just assign them in the code?
I am wondering if there are advantages to using ...
0
votes
1answer
475 views
Constructor Arguments for verification on Etherscan.io
I want to verify a contract on Etherscan.io, but I am not able to find the correct Constructor Arguments. I tried everything which is explained on StackExchange, but cannot get it to verify...
The ...
