From 8f1a0221cf53ef45a2567f905c40f69fc30fd010 Mon Sep 17 00:00:00 2001
From: p0n1 <36690236+p0n1@users.noreply.github.com>
Date: Sat, 9 Jun 2018 15:02:26 +0800
Subject: [PATCH] token-erc20: add event Approval to follow eip20

> MUST trigger on any successful call to approve(address _spender, uint256 _value).

https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md#approval

We audited many tokens without event Approval.
Should comply EIP20 for a better dApp ecosystem.
---
 solidity/token-erc20.sol | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/solidity/token-erc20.sol b/solidity/token-erc20.sol
index 0168ead4..8f3275ae 100644
--- a/solidity/token-erc20.sol
+++ b/solidity/token-erc20.sol
@@ -16,6 +16,9 @@ contract TokenERC20 {
 
     // This generates a public event on the blockchain that will notify clients
     event Transfer(address indexed from, address indexed to, uint256 value);
+    
+    // This generates a public event on the blockchain that will notify clients
+    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
 
     // This notifies clients about the amount burnt
     event Burn(address indexed from, uint256 value);
@@ -97,6 +100,7 @@ contract TokenERC20 {
     function approve(address _spender, uint256 _value) public
         returns (bool success) {
         allowance[msg.sender][_spender] = _value;
+        emit Approval(msg.sender, _spender, _value);
         return true;
     }