Example of running subcurrency in Ethereum

subcurrency_example.py

__author__ = 'loi'
sub_currency = """
init:
    # Initial: premine 1000000 units to creator
    contract.storage[msg.sender] = 1000000
code:
    # If a message with one item is sent, that's a balance query
    if msg.datasize == 1:
        addr = msg.data[0]
        return (contract.storage[addr])
    # If a message with two items [to, value] are sent, that's a transfer request
    else:
        from = msg.sender
        fromvalue = contract.storage[from]
        to = msg.data[0]
        value = msg.data[1]
        if fromvalue >= value:
            contract.storage[from] = fromvalue - value
            contract.storage[to] = contract.storage[to] + value
            return(1)
        else:
            return(0)
"""

import serpent
from pyethereum import transactions, blocks, processblock, utils
processblock.print_debug = 1
code = serpent.compile(sub_currency)
key = utils.sha3('cow')
addr = utils.privtoaddr(key)
#This is to initialize the contract
genesis = blocks.genesis({addr: 10**18 })

#The first field is a nonce - to determine the transaction and prevent the replay attack
#The second field is the amount of ether per gas - gas price
#The third field is the start gas
#The forth field is the endowment, don't really know what it is
#The fifth field is the code
tx1 = transactions.contract(0,10**12,10000,0,code).sign(key)
result, contract = processblock.apply_transaction(genesis,tx1)
print ('Initial balance of address %s is: %s' %(addr, str(genesis.get_storage_data(contract, addr))))

#Check balance of the address
tx2 = transactions.Transaction(1,10**12,10000,contract,0, serpent.encode_datalist([addr])).sign(key)
result, ans = processblock.apply_transaction(genesis,tx2)
print('Check balance of address %s: %s ' %(addr, str(serpent.decode_datalist(ans))))

# Send money
key2 = utils.sha3('cow2')
addr2 = utils.privtoaddr(key2)
tx3 = transactions.Transaction(2,10**12,10000,contract,0,
     serpent.encode_datalist([addr2,45])).sign(key)
print ('Sending 45 sub-currency from %s to %s' %(addr, addr2))
result, ans = processblock.apply_transaction(genesis,tx3)
print('Check balance of address %s: %s ' %(addr, str(genesis.get_storage_data(contract, addr))))
print('Check balance of address %s: %s ' %(addr2, str(genesis.get_storage_data(contract, addr2))))