Hi Michael,

Thanks for posting. I was unable to reproduce your issue based on the variable names you've given here. I tried using the debugger on this code:

import numpy as np  
import pandas as pd

def initialize(context):  
    prices50 = pd.Series(np.random.randn(50))  
    return None  

with an interrupt on the return None line. Does the assignment ma50 = prices50.mean() work for you with this skeleton code? Also, if you could provide me with some more details of your original situation, that would help me to solve the problem.

I think I figured it out.

And to clarify- my question was about assigning variables in the REPL environment of the debugger. I believe I was trying to inspect and play with the result of the context.ma50 = ma50 = prices50.mean() call when this happened.

Put a breakpoint on that line. Then, in the debugger manually try to assign the variable ma50 = prices50.mean() and print(ma50). And do the same for ma200. Then you should see it.

I guess the debugger must reserve variable names that are going to be assigned but haven't been assigned yet

def initialize(context):  
    context.security_list = [symbol('SPY')]  
    # Rebalance every day, 1 hour after market open.  
    schedule_function(my_rebalance, date_rules.every_day(), time_rules.market_open())  
    # Record tracking variables at the end of each day.  
    schedule_function(my_record_vars, date_rules.every_day(), time_rules.market_close())  


def before_trading_start(context, data):

    prices200 = data.history(context.security_list, 'price', 200, '1d')  
    prices50 = prices200[-50:]  
    context.ma50 = ma50 = prices50.mean()  
    context.ma200 = ma200 = prices200.mean()

You're right; the debugger reserves variable names that are going to be assigned later. Would you rather this isn't the case? If so I could put in a feature request for you.

:) Assuming that this was an intentional design decision- then I don't have nearly the information on the benefit trade-off of having it versus not having it to make that decision. And really, now that I understand that it's not a hard change for me.

I guess, to avoid confusion of future users, attempts to assign the variable should throw an informative exception instead of appearing like the assignment is successful- as it is now.