@kamino6382
Could you talk about the transaction cost and execution cost that pops up every time you use a method?
@SlimFast4U
WTF: Thanks for the technical videos, I'm happy to see videos that talk more about the technology of Ethereum and less about price speculation. I'd like to ask.. do you know of any projects out there to build a provably fair system for off-blockchain computation? The computational ability of Ethereum contracts is currently limited to small-scale use cases. Golem seems like the closest thing, but it seems to fall short, IMO. From what I can tell, it is susceptible to collusion; a lone dissenter has no way to prove themselves to have the correct output on-chain with a sort of "Socratic" or "bisect" method. In a way, enforcing consensus on the blockchain regardless if there are a majority of unscrupulous actors participating in the contract. Sample use case: Verify a GPG message/signature against a public key predefined in the contract. From what I understand, this use case is too computationally expensive to happen on-chain but is trivial to compute off-chain. Even if you are had thousands of ETH, it would take numerous blocks (gas limit per block) to do completely on-chain. I am sure this can be done off-chain with an on-chain proof mechanism in the case of disagreement, but wanted to know if you're aware of any project out there to do this - I haven't looked into every single ICO out there.
@incomemobile8566
I think your videos would become even more useful if you were to contextualize real world applications. In this video for instance you might say how the one calculator is pulling in say a mortgage amortization schedule calculator resting at another address .. or how you'd use the calculator of say an ROI model to determine the value of new x. Keep up the good work & get down on the funk tear the roof off the sucka. Parliament rocks!
@czepesch
Thank You for lesson! p.s. can you make your voice record a bit louder? Intro part is quite loud, then sound level is drops signifficantly
@sethishivam2753
Hi Wtfunc I have a question that why we didn't use reutnrs constant with function as it is returning a constant value .. like we use for getters ?
@anexperiment8523
Hi WTF, thanks for the great video! Could I ask if it is possible to split the two contracts into two different files? What if we're calling the calculator's functions but do not have access to the source code of the calculator?
@rwijupal9199
Hi WTF, Wanted to know how is it different from inheritance. Because in inheritance also we can get the function from another contract used in the current one.
@jlp0
I think I inputted identical code:
pragma solidity ^0.4.0;
contract Foo {
Calculator calc = new Calculator();
function twoTimesThree() constant returns(int) {
return calc.multiply(2, 3);
}
}
contract Calculator {
function add(int a, int b) returns (int) {
return a + b;
}
function multiply(int a, int b) returns (int) {
return a * b;
}
}
When I try to "Create" Foo, I get this error: "Exception during execution. (stack underflow). Please debug the transaction for more information."
Do you know what's causing this error?
I added the Calculator change:
pragma solidity ^0.4.0;
contract Foo {
Calculator calc = new Calculator(0xec5bee2dbb67da8757091ad3d9526ba3ed2e2137);
function twoTimesThree() constant returns(int) {
return calc.multiply(2, 3);
}
}
contract Calculator {
function add(int a, int b) returns (int) {
return a + b;
}
function multiply(int a, int b) returns (int) {
return a * b;
}
}
But I get these compiler errors:
"browser/Communication.sol:6:38: Warning: This looks like an address but has an invalid checksum. If this is not used as an address, please prepend '00'.
Calculator calc = new Calculator(0xec5bee2dbb67da8757091ad3d9526ba3ed2e2137);
^--------------------------------------^
browser/Communication.sol:7:23: TypeError: Wrong argument for function call: 1 arguments given but expected 0.
Calculator calc = new Calculator(0xec5bee2dbb67da8757091ad3d9526ba3ed2e2137);
^--------------------------------------^
Do you know why I get these errors but not you?
I'm using: https://remix.ethereum.org/#version=soljson-v0.4.13+commit.fb4cb1a.js
@thread_pool
I can't get it to work -> Warning: This looks like an address but has an invalid checksum. If this is not used as an address, please prepend \'00\'. 5 Stars!!
@tradingwithwill7214