SYNOPSIS

This is a direct fork of ethereumjs-vm with a few
(significant) modifications.

This repository is a Proof-of-Concept for a wallet side EVM execution(WEVM),
which brings several use cases which I want to explore in this POC project.
Possible use cases could be:
* Solidity based Deployment-Scripting
* (Server side) Sidechain

##Deployment-scripting

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* no context switching between development, testing or interacting

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* full solidity features
* dapples unit testing and integration testing

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Considder the setup of the following OnBlockchain Contract:
``
contract OnBlockchain {
event owner(address owner);
function OnBlockchain(bytes construcorrr) {
owner(msg.sender);
// hahaha
}
function giveMeTHIRTYTWO() constant returns (uint) {
return 32;
}
function giveMeSEVENTEEN(uint integer) returns (uint) {
return 17;
}
function giveMeFOUR() returns (uint) {
return 4;
}
}
`

`
contract B is Script {
function B() {

// deploys a new contract
OnBlockchain a = new OnBlockchain("123");

// export the contract address as variable "varname". Its class
// is automatically inferred
exportObject("varname", a);

// as the function giveMeTHIRTYTWO is constant, the function call
// triggers a call and retrieve a value and export it as the variable
// name "thirtytwo"
exportNumber("thirtytwo", a.giveMeTHIRTYTWO());

// The function giveMeSEVENTEEN is not static, therefore
// a transaction is triggered. However a return value
// can be still retrieved and exported (currently not working)
exportNumber("seventeen_nonstatic", a.giveMeSEVENTEEN(2));

// If one want to retrieve a return value from a function
// without triggering a transaction, this can be done either by
// setting the call flag to true:
setCalls(true);
exportNumber("seventeen", a.giveMeSEVENTEEN(3));
setCalls(false);

// or exporting the the static calls into a function:
staticStuff(b);

// sets the address which triggers the transaction
setOrigin(0x6deec6383397044107be3a74a6d50d41901f0356);

// this contract will have 0x6d... as its creator
OnBlockchain b = new OnBlockchain("123");

// Interacting with the default server environment is also supported
// In order for this to work, curl and jq need to be installed
uint BTC_USD = SH.to_uint("curl -s https://api.coindesk.com/v1/bpi/currentprice.json|jq '.bpi.USD.rate|tonumber|floor'");
exportNumber("btc_usd", BTC_USD);

// one can think of different integrations/ apis, which can be provided by
// dapple with this approach
}

// the static flag indicates, that all transactions in this function will be
// treated as static calls rather then generating a transaction
function staticStuff(OnBlockchain a) static {
exportNumber("four", a.giveMeFOUR());
}
}
`

This is producing the following output:
`
NEW new OnBlockchain(0x313233)
TXR OnBlockchain(0xac5fce7ae0051acf4dcd81a64523da41e59cc7a5).giveMeSEVENTEEN(2)
ACC switch origin to 0x6deec6383397044107be3a74a6d50d41901f0356
NEW new OnBlockchain(0x313233)


exportObject(name a, addr 0xac5fce7ae0051acf4dcd81a64523da41e59cc7a5, class OnBlockchain)
exportNumber(name thirtytwo, number 32)
exportNumber(name seventeen_nonstatic, number 1.13526946735478465913037617028159547472529646787646290075579373593588249133056e+77)
exportNumber(name seventeen, number 17)
exportNumber(name four, number 4)
exportNumber(name btc_usd, number 678)
`

##Sidechain
A sidechain running on Dapphub/ Controlled servers can be used to directly
interact with ethereum and dapple.
E.g. centralized callbacks can be deployed which are triggered by on
blockchain events.
external Plugins/ Packages/ Services can be easilly implemented and provided
through a standard dapphub api.
`

Contract c = new Contract();
Event(c).on("Trade", "sale");
...
}

function callback(address sender, string name, uint ammount) on("sale") {
sms.msg(me, "Got request, sold ${name} for ${ammount}");
}


`




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WEVM related stuff is located in ./src/. Also ethereumjs-vm's code was modified.
To test it for yourself run testrpc in the background and:
`
cd src
node index.js
``