Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #43724

Re: Understanding Boolean Expressions

Show all headers | View raw

Thank you all for thoughts.  I'm just about to post another question about atoms and primaries.  If you have a moment to look it over, I would appreciate your thoughts.

Many thanks in advance.

On Tuesday, April 16, 2013 6:19:25 PM UTC-4, Bruce McGoveran wrote:
> Hello.  I am new to this group.  I've done a search for the topic about which I'm posting, and while I have found some threads that are relevant, I haven't found anything exactly on point that I can understand.  So, I'm taking the liberty of asking about something that may be obvious to many readers of this group. 
> 
> 
> 
> The relevant Python documentation reference is:  http://docs.python.org/2/reference/expressions.html#boolean-operations.
> 
> 
> 
> I'm trying to make sense of the rules of or_test, and_test, and not_test that appear in this section.  While I understand the substance of the text in this section, it is the grammar definitions themselves that confuse me.  For example, I am not clear how an or_test can be an and_test.  Moreover, if I follow the chain of non-terminal references, I move from or_test, to and_test, to not_test, to comparison.  And when I look at the definition for comparison, I seem to be into bitwise comparisons.  I cannot explain this.
> 
> 
> 
> Perhaps an example will help put my confusion into more concrete terms.  Suppose I write the expression if x or y in my code.  I presume this is an example of an or_test.  Beyond that, though, I'm not sure whether this maps to an and_test (the first option on the right-hand side of the rule) or to the or_test "or" and_test option (the second on the right-hand side of the rule).  
> 
> 
> 
> If people can offer some thoughts to put me in the right direction (or out of my misery), I would appreciate it.
> 
> 
> 
> Thank you in advance.

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Understanding Boolean Expressions Bruce McGoveran <bruce.mcgoveran@gmail.com> - 2013-04-16 15:19 -0700
  Re: Understanding Boolean Expressions Walter Hurry <walterhurry@lavabit.com> - 2013-04-16 22:32 +0000
  Re: Understanding Boolean Expressions Dave Angel <davea@davea.name> - 2013-04-16 18:57 -0400
  Re: Understanding Boolean Expressions "Rhodri James" <rhodri@wildebst.demon.co.uk> - 2013-04-17 00:28 +0100
  Re: Understanding Boolean Expressions Terry Jan Reedy <tjreedy@udel.edu> - 2013-04-16 21:23 -0400
  Re: Understanding Boolean Expressions Bruce McGoveran <bruce.mcgoveran@gmail.com> - 2013-04-16 19:29 -0700
  Re: Understanding Boolean Expressions Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-04-17 08:14 +0000
    Re: Understanding Boolean Expressions Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-04-17 11:47 +0300
      Re: Understanding Boolean Expressions Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-04-17 09:20 +0000
        Re: Understanding Boolean Expressions Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-04-17 12:32 +0300

csiph-web