XOM API for Processing XML with Java

[Elliotte Rusty Harold <elharo AT metalab.unc.edu>]

At 6:55 PM -0800 12/2/02, Edwin Goei wrote:

> As for exceptions, I think users would expect that if the middle 
> call throws an exception, then the state would be just the same as 
> if the middle appendChild() call throws an exception in the 
> non-chained case. So I don't see how this is much different.

That's what does happen. It's not what everyone expects though. It 
looks like one statement. People expect it to act like one statement. 
Since it isn't actually one statement, it shouldn't pretend to be one.


> Perhaps your main objection is that you think mutator methods should 
> not return anything and not method chaining per-se.  Or is it both?

Both. If I had to summarize I'd say side effects are bad. Each public 
method call should have a single clear purpose which operates 
completely and independently of other method calls. The normal way 
this fails is method calls that aren't complete; e.g. you have to 
call methods 1, 2, and 3 in order to make something happen. They 
can't be treated in isolation. However, the problem here is the 
opposite: methods that do too many things that could and should be 
independent.
--

+-----------------------+------------------------+-------------------+
| Elliotte Rusty Harold | elharo AT metalab.unc.edu | Writer/Programmer |
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|          XML in a  Nutshell, 2nd Edition (O'Reilly, 2002)          |
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|  http://www.amazon.com/exec/obidos/ISBN%3D0596002920/cafeaulaitA/  |
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