[2308] in java-interest
Re: throws declataration in Java/beta
daemon@ATHENA.MIT.EDU (Jim Graham)
Fri Sep 29 06:54:07 1995
Date: Fri, 29 Sep 1995 01:45:42 -0700
From: flar@bendenweyr.Eng.Sun.COM (Jim Graham)
To: garya@village.org
Cc: java-interest@java@sun.com
> >Only forseen exceptions are generally required to be declared (and
> >therefore need to be caught or explicitly passed on). Exceptions which
> >are subclasses of RuntimeException or Error - which are not generally
> >part of the API of a given method - don't have to be declared.
> >Exceptions such as IOException, which are part of the natural working
> >domain of many methods, must be declared where they can occur so that
> >callers of that method are aware that the indicated exception is a
> >possible result of calling the method.
>
> It seems to me that this reasoning has a flaw.
> It assumes that the base class designer can forsee all possible algorithms
> needed by all possible subclasses, and include the necessary exception
> declarations to cover them. Unfortunately, it can't, which is why the
> whole problem arises. No base class can forsee anything about the
> mechanisms needed by a subclass to implement a different but functionally
> equivalent or complementary, task.
Can you give a concrete example? If a subclasser wants to throw a new
kind of exception, then he is most likely trying to fit a round peg into
a square hole...
...jim
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