This is emphatically not about Scala. Nor is pattern matching unique to
Scala either. It's standard in most FP languages, and even Java offers a
very rudimentary form through switch statements and the exception handling
syntax.
Let's pretend that Java could handle this as I propose, using a mash-up of
`switch` and exception handling syntax, how might it look? (assuming I
retain commonplace Java idioms as much as possible)
match(fileOpen(fileName)) {
case(FileNotFound status) { ... }
case(IllegalFilename status) { ... }
case(FileOpened fo) {
FileHandle handle = fo.getHandle();
doSomethingWithFile(handle);
moreFileOps(handle);
yetSomethingElse(handle);
.
.
keepGoing(handle);
.
.
promiseThisIsTheLastOne(handle);
}
}
//if there were other subclasses of FileOpenStatus, the compiler would
warn you at this point
//other unanticipated problems can still throw an unchecked exception
This is, of course, just a proof of concept. There are clearly improvements
to be had here, but at least it demonstrates the basic idea: A way to
represent and handle divergent (yet expected) return types without recourse
to explicit casting or checked exceptions.
On 23 September 2010 00:26, Miroslav Pokorny <[email protected]>wrote:
> It seems to me that Kevin always unconditionally says some construct unique
> to Scala is better than a Java equivalent even giving examples and
> reasonings that are for all intents and purposes identical in form,
> functionality and readability... The try catch example for opening a file is
> perfect example.
>
> Kevin please give examples with real differences!!!
>
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--
Kevin Wright
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