Python and Flaming Thunder

[Duncan Booth]

Dave Parker <daveparker at flamingthunder.com> wrote:

> Catch also gives you a
> single, uniform, syntactically unambiguous way to embed statements (or
> whole statement lists) into expressions -- without causing the
> syntactic problems of = statements in if statements or the obfuscation
> of question mark notation, etc.  For example:
> 
> If catch(set x to y+z.) < 0.1 then go to tinyanswer.
> 
So what does this do exactly if the set throws an error? Is the error 
message printed at the top level going to be telling you about the failed 
addition or the failed comparison? Why do you need the catch anyway, if a 
statement is just an expression why can't you just put the statement into 
parentheses?

For that matter, is there any way to distinguish between different errors 
and only catch particular ones? A bare except clause in Python is usually a 
signal of bad code: when handling errors you only want the errors you have 
anticipated, and want to be sure that any unexpected errors don't get 
caught.

You have a great opportunity to avoid making some of the same mistakes that 
Python is trying to get out of. For example as of Python 2.5 
KeyboardInterrupt and SystemExit to longer inherit from Exception. That 
means a bare except in Python no longer catches either of those: if you 
want to handle either of these exceptions you have to be explicit about it.


-- 
Duncan Booth http://kupuguy.blogspot.com