At 01:19 PM 4/24/2006 -0700, Aahz wrote: >What is EXPRESSION, then? Not the value it returns, but EXPRESSION >itself -- does it have a name? What about the kinds of things we use >for EXPRESSION?
I read "EXPRESSION returns a value" as simply meaning that "value = EXPRESSION", i.e. that the result of computing EXPRESSION *is* the value. That's what it usually means when we talk about expressions returning a value -- that computing the expression produces a value. I still don't see a third thing here. "EXPRESSION returns a value" (Thing 1). That value is "used to create a context" (by calling __context__). This context (Thing 2) "is used to execute a block" (by calling __enter__ and __exit__). I don't get how you can have a difference between "EXPRESSION" and "value it returns" unless you're bringing functions into play. In everything else in Python, an expression *is* the value it returns. How could it be otherwise? Maybe you meant to write an explanation that included three objects, but what you wrote is actually a precise and accurate description of how things works. The value produced by EXPRESSION is used to create a context, and the context is used to execute the block. I don't know how you could explain it any more simply than that -- certainly not by adding a mysterious third gunman on the grassy knoll. :) _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
