OpenEuphoria

Re: Py 2.6b Update

• Posted by Matthew Lewis <MatthewL at KAPCOUSA.COM> Dec 01, 2000
• 549 views

> From: David Cuny

>    ? 5-3+2

> in Py, you get 0 instead of 4. I always seem to have trouble with this
> left/right associativity business.

<nitpick>

I'd call this a distributive problem:

distributive:
? 5-1*(3+2)
instead of
? 5+1*(-3+2)

associative:
? (5-3)+2
? 5+(-3+2)

</nitpick>

Dealing with subtraction (esp symbolically) can be a pain:

-- It's not commutative.
-- Do you treat subtraction as adding a negative number?
-- Subtracting a positive?
-- What if there's a variable in the expression?
-- What if you're just looking for a negative number ( '? -1' ).

I had lot's of errors writing Matheval (see the archives :), and eventually
hacked the parser enough to treat negative/minus signs somewhat
consistently.

Matt Lewis
http://www.realftp.com/matthewlewis