Replace NEP-5 with NEP-17

[erikzhang]

Differences from NEP-5:

1. Added onPayment call if the receiver is a deployed contract.
2. Removed payable check. It has been replaced by onPayment.
3. Removed name method, because it should be in manifest for all the contracts, not only for the token contracts.
4. Changed the transfer event to capitalize the first letter Transfer.

[erikzhang]

@shargon @ixje @roman-khimov @vncoelho @EdgeDLT @igormcoelho @neo-project/ngd-shanghai

[ixje]

First off, happy to see this new NEP 👍 I think an extension to NEP5 could have done, but completely superseding is fine with me as well.

Note that there is a downside to removing the name function for light wallets. Currently a light wallet can create a single script and use a single invokescript RPC call to fetch the name, symbol, decimals and totalSupply. Changing this requires another RPC call (getcontractstate) and fetch the name from there (I'm guessing from the extra field, of which the content aren't standardised)

[shargon]

Add transferFrom and allowance?

[vncoelho]

@shargon, what would be transferFrom and allowance?

[ixje]

@shargon, what would be transferFrom and allowance?

you allow another account to transfer from an account you own. The other account uses transferFrom

[erikzhang]

Add transferFrom and allowance?

With approve and transferFrom, you need two steps. In Neo3, we don't need them. With transfer and onPayment, you only need one step.

[igormcoelho]

It would be interesting to also invite previous authors of NEP-5 to join this NEP-17 for discussion, or even, authorship (if they agree too).

[igormcoelho]

P.S.: just noticed you informed that on the TODO list, requiring people to submit Pull Request. That's fine then.

[vncoelho]

Ping @lllwvlvwlll to discuss with other authors of NEP-5.

[Tommo-L]

Removed name method, because it should be in manifest for all the contracts, not only for the token contracts.

Then we'd better add author, description, email, website in manifest file, too

[erikzhang]

Then we'd better add author, description, email, website in manifest file, too

They can be in Extra.

[roman-khimov]

I think we also need to limit it for the same reasons (at least to int64), and balanceOf as well.

[lllwvlvwlll]

Boa Reference: https://github.com/CityOfZion/neo3-boa/blob/development/boa3_test/examples/NEP17.py

[chenzhitong]

Should we add the onPayment method to the standard methods of NEP-17 or C# smart contract template?

[erikzhang]

@chenzhitong onPayment is a receiver method.

[chenzhitong]

If a receiver doesn't implement the onPayment method, will the transfer execute fail?
接收者不实现onPayment ，转账是否会报错？

In addition, should the manifest of the NEP-7 method must be written

"permissions": [
  {
    "contract": "*",  
    "methods": "*"
  }
]

, because it needs to call the onPayment method of to.
是不是所有的NEP-17方法都要在manifest中添加上述的permission，因为它需要调用to的onPayment方法
@erikzhang

[erikzhang]

{
  "contract": "*",  
  "methods": "onPayment"
}

[chenzhitong]

那一个合约（ICO合约）想接收别人给他转账，是不是要在 manifest 中这么写
"trusts": *
这样岂不是很不安全。
@erikzhang

[erikzhang]

"trusts": *

For example, if the ICO contract needs to receive neo, it has to trust neo. I don't think an ICO can accept any type of tokens.

[satoshichou]

When will it be merged to master. The proposal seems is already implemented in native ocntract.

[erikzhang]

Merge?

[superboyiii]

I think it's OK to merge.

[RichardBelsum]

Celebrate🎉