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BuyTokens getting rate from a function instead of field. Useful for making Crowdsales with bonus periods #632

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BuyTokens getting rate from a function instead of field. Useful for making Crowdsales with bonus periods #632

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f73de1f
Adding Periodic Crowdsale
Dec 21, 2017
563831f
Removed useless contract
Perseverance Dec 29, 2017
06b3c5e
Minor version increase
Perseverance Dec 29, 2017
8f4125a
Adding Periodic Crowdsale
Dec 21, 2017
5052955
Merge branch 'master' of https://github.com/LimelabsTech/zeppelin-sol…
Perseverance Dec 29, 2017
6a53b05
Adding Periodic Crowdsale
Dec 21, 2017
fc3653b
Merge branch 'master' of https://github.com/LimelabsTech/zeppelin-sol…
Perseverance Dec 29, 2017
7aa6f21
fix: TokenDestructible typo fron->from
shrugs Dec 31, 2017
9aa61ad
Merge pull request #634 from Shrugs/fix/destructible-typo
spalladino Jan 2, 2018
58ecbd6
fix typo: that -> than
Dec 8, 2017
52b2a61
Merge pull request #603 from elopio/patch-1
spalladino Jan 2, 2018
431bb2d
Adding Periodic Crowdsale
Dec 21, 2017
8d4d57b
Removed useless contract
Perseverance Dec 29, 2017
f569691
Minor version increase
Perseverance Dec 29, 2017
c07ebb4
Changed getRate to getTokenAmount. The function is now used to calcul…
Perseverance Jan 2, 2018
6e73666
Merges
Perseverance Jan 2, 2018
f37ca0e
Fix left out merge token
Perseverance Jan 3, 2018
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Adding Periodic Crowdsale
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@Perseverance
Georgi Spasov authored and Perseverance committed Dec 29, 2017
commit 6a53b0529c1a7534f80c15ccbb9e83ac3be6d0e2
8 changes: 7 additions & 1 deletion contracts/crowdsale/Crowdsale.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -65,6 +65,11 @@ contract Crowdsale {
buyTokens(msg.sender);
}

// determines the rate of the crowdsale. Override this for periodization logic
function getRate() internal constant returns(uint256) {
return rate;
}

// low level token purchase function
function buyTokens(address beneficiary) public payable {
require(beneficiary != address(0));
Expand All @@ -73,7 +78,8 @@ contract Crowdsale {
uint256 weiAmount = msg.value;

// calculate token amount to be created
uint256 tokens = weiAmount.mul(rate);
uint256 _rate = getRate();
uint256 tokens = weiAmount.mul(_rate);
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@grimsa grimsa Jan 2, 2018 •
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Wouldn't extracting getTokenAmount(weiAmount) with default implementation of weiAmount.mul(rate) be more flexible?

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@Perseverance Perseverance Jan 2, 2018

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I am not really sure which one is more flexible :) I wanted to keep the code as similar to the original one

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@grimsa grimsa Jan 2, 2018

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I had two scenarios in my mind:

  1. Applying multiple price levels to a transaction, for example:
    • You have a crowdsale with a bonus period where you are minting tokens at 25% increased rate until GOAL wei are raised.
    • Let's say you have raised (GOAL - 10 wei) already and a big transaction comes sending 10k ETH. You only want to mint (10 wei * 25%) worth of bonus tokens (not 10K ETH * 25 %).
  2. Rounding problems when original rate = 1. Example:
    • If you want to implement 1 ETH = 1 Token crowdsale, you'll use a rate of 1 and a token with 18 decimal places.
    • Now if you want to issue tokens at 125% rate at first, you have a problem, as getRate result will be 1 (original rate) * 5/4, which rounds down to 1, hence, no bonus.

It is impossible to implement any of these two by just overriding getRate().

As you can always override getTokenAmount(weiAmount) and implement it as weiAmount.mul(getRate()) with a custom getRate() function, to me it seems like a superior approach.

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@Perseverance Perseverance Jan 2, 2018

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You are right, will rewrite it ASAP ;)


// update state
weiRaised = weiRaised.add(weiAmount);
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4 changes: 2 additions & 2 deletions package.json
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@@ -1,6 +1,6 @@
{
"name": "zeppelin-solidity",
"version": "1.4.0",
"version": "1.4.1",
"description": "Secure Smart Contract library for Solidity",
"scripts": {
"test": "scripts/test.sh",
Expand Down Expand Up @@ -52,4 +52,4 @@
"dependencies": {
"dotenv": "^4.0.0"
}
}
}