Program logic bugs vs input/environmental errors

[Bruno Medeiros via Digitalmars-d]

On 28/09/2014 00:15, Walter Bright wrote:
> This issue comes up over and over, in various guises. I feel like
> Yosemite Sam here:
>
> https://www.youtube.com/watch?v=hBhlQgvHmQ0
>
> In that vein, Exceptions are for either being able to recover from
> input/environmental errors, or report them to the user of the application.
>
> When I say "They are NOT for debugging programs", I mean they are NOT
> for debugging programs.
>

This is incorrect.

Yes, the primary purpose of Exceptions is not for debugging, but to 
report exceptional state to the user (or some other component of the 
system).

But they also have a purpose for debugging, particularly the stack 
traces of exceptions. Take what you said:

"Failure to respond properly to an input/environmental error is a bug.
But the input/environmental error is not a bug. If it was, then the
program should assert on the error, not throw. "

So, some component/function Foo detects an environmental error, and 
throws and Exception, accordingly. Foo is not responsible for handling 
these errors, but some other component is.

Component/function Bar is the one that should handle such an error (for 
example, it should display a dialog to the user, and continue the 
application). But due to a bug, it doesn't do so, and the Exception goes 
all the way through main().

The programmer notices this happening, and clearly recognizes it's a bug 
(but doesn't know where the bug is, doesn't know that it's Bar that 
should be handling it). Now, what is best, to just have the Exception 
message (something like "File not found") displayed to the programmer - 
or even an end-user that could report a bug -, or to have the stack 
trace of the Exception so that the programmer can more easily look at 
which function should be handling it?

-- 
Bruno Medeiros
https://twitter.com/brunodomedeiros