[Tutor] bnf

Danny Yoo dyoo at hkn.eecs.berkeley.edu
Sun Dec 11 03:23:20 CET 2005

> >   hello everyone. i was looking at python docs and i came across this
> >
> >   letter ::=
> >                lowercase | uppercase
> >
> >
> >   what does ::= mean?
> goodness knows, maillists and usenet would be better if more people
> (myself included) would do a better job of their own googling. But,
> I'm not sure that your comment is fair in this context. Maybe my
> google-fu is lacking, but googling for ::= or "::=" doesn't produce
> anything.

The question is a little mixed here.  I agree that '::=' is obscure enough
that asking for help about it is certainly appropriate and right.

At the same time, though, there's a section right at the beginning of the
Python Reference Manual that does talk about the notation used in the rest
of the document:


Ideally, the original poster would have found and seen the "notation"
section of the reference manual, at least to get a good name for what
they're looking at --- "BNF" format.  Then we're in a better position to
ask what in the world BNF is.

I think the lesson here is: let's encourage people to learn how to read
technical documentation, by pointing out the conventions that technical
writers will use.  In technical documentation that uses weird notation,
there will usually be a section called "Notation" that at least will try
to give English names to the weird symbols.

Good luck to you!

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