On Thursday, 6 July 2017 at 11:01:26 UTC, Marco Leise wrote:
Am Thu, 06 Jul 2017 01:31:44 +0000
schrieb Moritz Maxeiner <[email protected]>:
But to be clear (and the title and description of any DIP
addressing this should reflect this):
These are not checked exceptions, because checked exceptions
would require bar to declare its exception set manually.
Yep, absolutely clear. Just like "auto a = 1" does not declare
a variable as we all know declarations start with a type.
Red herring.
Checked exceptions are well defined - not just implemented - (by
Java as the de facto authority for the term) as requiring the
declaration of all exceptions (that aren't inherited from some
special class, in Java's case `RuntimeException`, in D's it would
be `Error`) that may be thrown by a function as a result of its
body being executed [1]. If even a single function is allowed to
have its exception set defined by inference (instead of
declaration), you are not implementing checked exceptions.
---
void foo() throws AExp throws BExc { ... }
void bar1() { foo(); } // Checked exceptions require this to
result in a compilation error
void bar2() throws AExc throws BExc { foo(); } // this must be
used for checked exceptions
---
Instead of defining checked exceptions how it bests fits all
your posts in this thread, why not say "Checked exceptions as
implemented in Java were a good idea, had they allowed the
compiler to infer them where possible."
Invalid premise. The definition of checked exceptions is de facto
fixed by Java [1], because it not only coined the term but
remains the only major PL to use them.
Of course we can still call those inferred checked exceptions
something else. ;o)
The java compiler does infer an exception set for every function
based on its body.
This is then checked against the function's exception set as
declared in its signature.
"inferred checked exceptions" is thus an oxymoron, because it
would mean checking the inferred exception set against itself.
[1]
https://docs.oracle.com/javase/7/docs/api/java/lang/Exception.html
