RC2_SYMBOL_EXTRA_POSITIONAL

Symbol() takes at most one positional argument (the ticker). Pass broker=, session=, trade= as keyword arguments.

What it means

Symbol() has exactly one positional slot, and it means ticker. Everything else is keyword-only. There is no positional order to memorise, which is deliberate: a slot declaration is read far more often than it is written, and Symbol("SPY", "tradestation") would leave every reader guessing whether the second string is a broker, a session, or an exchange.

Why it happens

Habit from broker APIs and other DSLs, where a symbol constructor takes a positional tuple:

class PositionalBroker(Strategy):
    trade = Symbol("SPY", "tradestation")
    sizing = FixedCapital()

    def execute(self):
        if self.trade.is_flat:
            self.buy(self.trade)

How to fix it

Keep the ticker positional if you like it that way; name everything else.

class NamedArgs(Strategy):
    trade = Symbol("SPY", broker="tradestation", session=USEquityDaily)
    sizing = FixedCapital()

    def execute(self):
        if self.trade.is_flat:
            self.buy(self.trade)

Related

• Symbol()
• RC2_SYMBOL_TICKER — the one positional arg, given twice or given as something other than a string literal.
• RC2_ENTRY_EXTRA_ARG — the same “that’s a kwarg, not a positional” rule on the order verbs.