SETTINGS
In order to create a PM, we will need to set a particular parameter when creating the asset. This parameter can not be changed after creation of the asset.
Further, A PM-asset should have the following flags (not permissions):
{
"disable_force_settle" : true,
"global_settle" : false,
"witness_fed_asset" : false,
"committee_fed_asset" : false
}and these MPA-options:
{
"feed_lifetime_sec" : 60 * 60 * 24 * 356,
"minimum_feeds" : 1,
"force_settlement_delay_sec" : 60
"force_settlement_offset_percent" : 0
"maximum_force_settlement_volume" : 100 * GRAPHENE_1_PERCENT,
"short_backing_asset" : "1.3.0",
}Note
Unfortunatelly, create_asset cannot create prediction markets. Thus, we need to construct our asser_create_operationmanually (see below).
Note
The precision of the prediction market asset has to be identical with the short backing asset’s precision.
SETTLEMENT AUTHORITIES
The issue can choose between three parties that are allowed to settle the prediction market:
- Committee
- Witnesses
- Other accounts
Committee
If only the committee is supposed to be able to settle the market, you need to set the options to :
{
"witness_fed_asset" : false,
"committee_fed_asset" : true
}Witnesses
If only the witnesses are supposed to be able to settle the market, you need to set the options to :
{
"witness_fed_asset" : true,
"committee_fed_asset" : false
} Note
The idea here is that the median of all price feeds published by the witnesses indicates a positive or negative resolution of the prediction market.
Other Accounts
Similar to Privatized BitAssets, the feed can be also published by a arbitrary set of accounts. It is important to understand that in order to settle a prediction market, only one price feed is requried. Hence, anyone in the list of allowed settlers can settle the market and no consensus needs to be reached. Alternatively, if you want to settle a market only if several accounts can reach a consensus, a new resulution account can be created that uses hierarchical multi-signature similar to the committee-account.The list of settlement price producers can be defined with:
>>> update_asset_feed_producers <symbol> ["account-a", "account-b"] truePYTHON EXAMPLE
from grapheneapi import GrapheneClient
import json
perm = {}
perm["charge_market_fee"] = 0x01
perm["white_list"] = 0x02
perm["override_authority"] = 0x04
perm["transfer_restricted"] = 0x08
perm["disable_force_settle"] = 0x10
perm["global_settle"] = 0x20
perm["disable_confidential"] = 0x40
perm["witness_fed_asset"] = 0x80
perm["committee_fed_asset"] = 0x100
GRAPHENE_100_PERCENT = 10000
GRAPHENE_1_PERCENT = GRAPHENE_100_PERCENT / 100
class Config():
wallet_host = "localhost"
wallet_port = 8092
wallet_user = ""
wallet_password = ""
if __name__ == '__main__':
graphene = GrapheneClient(Config)
issuer = "nathan"
symbol = "PMMP"
backing = "1.3.0"
account = graphene.rpc.get_account(issuer)
asset = graphene.rpc.get_asset(backing)
permissions = {"charge_market_fee" : True,
"white_list" : True,
"override_authority" : True,
"transfer_restricted" : True,
"disable_force_settle" : True,
"global_settle" : True,
"disable_confidential" : True,
"witness_fed_asset" : True,
"committee_fed_asset" : True,
}
flags = {"charge_market_fee" : False,
"white_list" : False,
"override_authority" : False,
"transfer_restricted" : False,
"disable_force_settle" : True,
"global_settle" : False,
"disable_confidential" : False,
"witness_fed_asset" : False,
"committee_fed_asset" : False,
}
permissions_int = 0
for p in permissions :
if permissions[p]:
permissions_int += perm[p]
flags_int = 0
for p in permissions :
if flags[p]:
flags_int += perm[p]
options = {"max_supply" : 10000000000,
"market_fee_percent" : 0,
"max_market_fee" : 0,
"issuer_permissions" : permissions_int,
"flags" : flags_int,
"core_exchange_rate" : {
"base": {
"amount": 10,
"asset_id": asset["id"]},
"quote": {
"amount": 10,
"asset_id": "1.3.1"}},
"whitelist_authorities" : [],
"blacklist_authorities" : [],
"whitelist_markets" : [],
"blacklist_markets" : [],
"description" : "Prediction Market"
}
mpaoptions = {"feed_lifetime_sec" : 60 * 60 * 24 * 14,
"minimum_feeds" : 1,
"force_settlement_delay_sec" : 10,
"force_settlement_offset_percent" : 0 * GRAPHENE_1_PERCENT,
"maximum_force_settlement_volume" : 100 * GRAPHENE_1_PERCENT,
"short_backing_asset" : asset["id"],
}
op = graphene.rpc.get_prototype_operation("asset_create_operation")
op[1]["issuer"] = account["id"]
op[1]["symbol"] = symbol
op[1]["precision"] = asset["precision"]
op[1]["common_options"] = options
op[1]["bitasset_opts"] = mpaoptions
""" This flag will declare the asset as a prediction market
asset!
"""
op[1]["is_prediction_market"] = True
handle = graphene.rpc.begin_builder_transaction()
graphene.rpc.add_operation_to_builder_transaction(handle, op)
graphene.rpc.set_fees_on_builder_transaction(handle, "1.3.0")
tx = graphene.rpc.sign_builder_transaction(handle, True)
print(json.dumps(tx, indent=4))
source : http://docs.bitshares.org/bitshares/tutorials/pm-create-manual.html