Checked vs unchecked exceptions

[Moritz Maxeiner via Digitalmars-d]

On Tuesday, 27 June 2017 at 21:47:49 UTC, jag wrote:
> On Tuesday, 27 June 2017 at 19:37:24 UTC, Moritz Maxeiner wrote:
>>
>> As I have pointed out, your example occurs on the *caller* 
>> side, not the *callee* side. The proper solution is not for 
>> the callee to specify which exceptions it may throw, but for 
>> the caller to specify which exceptions it allows the callee to 
>> throw (using compile time introspection on the exception set).
>
> Can I as a programmer who wants to call a function written by 
> someone else inspect the declaration of that function and know 
> what exceptions are possible?

* Can I as a programmer who wants to call a function written by 
someone else inspect that function's exception set?

Yes, as explained fully here [1], shown as an idiomatic D trait 
here [2], and a template based abstraction around that trait here 
[3]. It would need to be implemented, of course, but it's not 
conceptually hard.

> If no how is this supposed to work?

It was explained multiple times in this thread.

> I am supposed to specify that exceptions I want to allow the 
> called function to throw?

You aren't supposed to do anything, but you can do that, yes.

> The called function is not going to dynamically adapt itself 
> and change the list of exceptions it throws, right?

What? A function's exception set is determined by its body and 
can be aggregated by the compiler in a single recursive pass in 
the static analysis phase.

> So how can I know, before running the code, what exceptions are 
> possible?

You mean the very first time you want to call it and you don't 
know the exception set yourself by looking at its signature?
Put the call in a nothrow scope and compile the module (which is 
fast in D), the compiler will then complain which exceptions you 
didn't catch (requires improvement of nothrow analysis [1]).

[1] 
http://forum.dlang.org/post/uovtkvpdagzagzhyacbp@forum.dlang.org
[2] 
http://forum.dlang.org/post/lxejskhonjtiifvvgwnd@forum.dlang.org
[3] 
http://forum.dlang.org/post/fjjkqbxiznlxfstqntnv@forum.dlang.org