One thing I like about `enforce` is that the program's run-time
checks become positive instead of negative statements which I
think is a lot more readable. i.e.
enforce(foo && bar > 4, "...");
instead of
if(!foo || bar <=3) throw new Exception("...");
I agree with Adam that importing `std.conv` everytime for `text`
is annoying, as is the whole subclassing and forwarding
constructor parameters.
Atila
On Wednesday, 13 May 2015 at 22:55:22 UTC, Steven Schveighoffer
wrote:
On 5/13/15 3:24 PM, Jacob Carlborg wrote:
On 2015-05-13 17:08, Adam D. Ruppe wrote:
Have you ever done:
if(something) {
import std.conv;
throw new Exception("some error " ~ to!string(some_value));
}
Don't you hate it?
* having to import std.conv to see data from your exception
is a pain
* it allocates eagerly and thus isn't suitable for a lot of
places
* inspecting the data can be a pain as the string is
unstructured
This assumes the data is even bothered to be added. Anyone
who has
gotten a RangeError in D knows important information is often
just
dropped!
A good solution is to make a new exception subclass for each
error type,
storing details as data members. However, that's a bit of a
pain in D
because of all the work you have to do to make a complete
subclass:
Yeah, I really hate that people are using plain Exception
instead of
creating a subclass. I'm trying to point this out in pull
requests and
similar but it's hard to get people to listen.
One thing that is _not_ making things better is "enforce"
which, if I
recall correctly, throws Exception by default.
enforce is one of the most needless pieces of phobos:
enforce(cond, message);
vs.
if(!cond) throw new Exception(message);
And the second doesn't mess up inlining.
I think enforce could be boiler-plated better. The only verbose
part of the if version is the throwing and newing.
template throe(Etype = Exception)
{
void throe(Args...)(Args args, string file = __FILE__,
size_t line = __LINE__)
{
throw new Etype(args, file, line);
}
}
if(!cond) throe(message);
Wait, you're in an io package, and you want to always throw IO
exceptions?
alias except = throe!IOException;
if(!cond) except(args, to, ioexception);
Sure, it doesn't return the thing that caused the exception if
nothing happens. Grepping phobos, this feature is used with
enforce about 1% of the time. In fact, I didn't even know it
had that feature until looking it up in the docs just now.
-Steve
