[Tutor] UnboundLocalError and Break

Dave Angel davea at ieee.org
Thu Oct 1 05:13:57 CEST 2009

Corey Richardson wrote:
> Luke Paireepinart wrote:
>> If your code's more than 10 lines long or so,  put it on pastebin.com 
>> <http://pastebin.com> and send us the link rather than inlining the 
>> whole thing.  You could also send it as an attachment.
>> Your formatting is all screwed up and I can't read the code at all, 
>> but I have an idea about your error.
>> Hmmm...thats odd. I didn't do anything different....but I can do 
>> that.http://pastebin.com/m518f612f
>>     <http://mail.python.org/mailman/listinfo/tutor>
The pastebin version of the code is substantially different than the 
original pasted version, and although the error message doesn't 
correspond to the posted code, at least there's enough to identify the 
particular error.

Line 21:      playHp -= damage #Player takes damage (I think...I will 
have to work that out)

in the function monsAttk() is trying to modify a local variable playHp, 
without initializing it.  Nowhere else in the function is that variable 
referenced or defined.

So you get a
UnboundLocalError: local variable 'playHp' referenced before assignment

What you undoubtedly meant to do is to subtract damage from the *global* 
variable playHp.  But without a global declaration, that's not what 
happens.  It tries instead to adjust a local variable by that name.  And 
of course that local is unbound.

The "fix" could be to make the function look like this:

      def monsAttk (damage, attack): #A monsters attack 
   2.     global playHp             #declare that we'll be modifying a
      global variable by this name, not defining a local
          if attack > deff:  #Monster hit  
              playHp -= damage #Player takes damage (I think...I will
      have to work that out)
              print "You have sustained", damage, "damage, with",
      damage-playHp, "remaining" #Inform player of their statu

I have to try hard to resist attacking your indiscriminate use of global 
variables.  But you said to just help on the one problem....


More information about the Tutor mailing list