Ethereum example of contract calling itself

recursive_example.py

__author__ = 'loi'
contract_code = '''
command = msg.data[0]
if command == 1:   #option 1
    contract.storage[0] = 99
    contractToCall = msg.data[1]
    tmp = call(contractToCall, [2], 1)
    return (tmp)
#option 2
elif command == 2:
    contract.storage[0] = 1
    return ('bb')
'''

import serpent
from pyethereum import transactions, blocks, processblock, utils

code = serpent.compile(contract_code)
key = utils.sha3('cow')
addr = utils.privtoaddr(key)

#initialize the block
genesis = blocks.genesis({addr: 10**18})

#This is to initialize the contract
tx1 = transactions.contract(0,10**12,10000,0,code).sign(key)
result, contract = processblock.apply_transaction(genesis, tx1)

#Call the contract
#nonce, gasprice, startgas, to, value, data
tx2 = transactions.Transaction(1, 10**12, 100000, contract, 0,  serpent.encode_datalist([1, contract])).sign(key)
result, ans = processblock.apply_transaction(genesis,tx2)
print genesis.to_dict()
print('Storage at location 0 is: %s' %str(hex(genesis.get_storage_data(contract, 0))))
print 'answer ' + str(ans)