[Issue 7838] Give some error messages for wrong ranges
https://issues.dlang.org/show_bug.cgi?id=7838 RazvanN changed: What|Removed |Added Status|NEW |RESOLVED CC||razvan.nitu1...@gmail.com Resolution|--- |LATER --- Comment #5 from RazvanN --- The problem with this is that it might brake code that implements some of the range functions but doesn't care about the others. Also, I don't think identifying why an entity is not a range is that problematic. Since this issue is rather old and people have not been complaining about this, I will close as LATER. If this comes up again, please reopen. --
[Issue 7838] Give some error messages for wrong ranges
http://d.puremagic.com/issues/show_bug.cgi?id=7838 --- Comment #4 from bearophile_h...@eml.cc 2012-04-06 11:06:31 PDT --- (In reply to comment #3) > It's just a little ugly because there will end up being nearly > duplicate templates for all the different range types. I think putting such test code inside DMD itself doesn't reduce the overall complexity a lot... -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 7838] Give some error messages for wrong ranges
http://d.puremagic.com/issues/show_bug.cgi?id=7838 --- Comment #3 from Matt Peterson 2012-04-06 10:47:21 PDT --- Yeah, I think the best solution is to add verifyInputRange etc. templates to std.range, where each criteria is checked by a separate static assert. It's just a little ugly because there will end up being nearly duplicate templates for all the different range types. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 7838] Give some error messages for wrong ranges
http://d.puremagic.com/issues/show_bug.cgi?id=7838
--- Comment #2 from bearophile_h...@eml.cc 2012-04-06 10:09:17 PDT ---
(In reply to comment #1)
> My understanding is that you would usually put a static assert with
> isInputRange, or a more specific template from std.range immediately after the
> struct.
This is an example program:
import std.range, std.bigint;
struct Powers {
int m;
BigInt n;
this(int m_) { this.m = m_; }
const bool empty = false;
BigInt front() { return n ^^ m; }
void popFront() { n += 1; }
}
static assert(isInputRange!Powers);
void main() {}
If I compile it with DMD 2.059beta:
...>dmd -property -run temp.d
temp.d(10): Error: static assert (isInputRange!(Powers)) is false
So it gives me no hint where the problem is. A built-in error message is
supposed to be more precise.
As alternative, maybe there is a way to add focused error messages inside a
isInputRangeVerify template to be used to verify that an input range is
correct, that uses pragma(msg) or better ctWriteln.
> How is DMD supposed to know that that struct is suppose to be a range
> otherwise?
I see, it's a problem.
So here we are talking more about a probabilistic compiler tip. If the
class/struct contains a popFront and front and empty methods then the
programmer probably meants it to be a range.
Thank you for your answer.
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[Issue 7838] Give some error messages for wrong ranges
http://d.puremagic.com/issues/show_bug.cgi?id=7838 Matt Peterson changed: What|Removed |Added CC||revcompg...@gmail.com --- Comment #1 from Matt Peterson 2012-04-05 19:42:00 PDT --- My understanding is that you would usually put a static assert with isInputRange, or a more specific template from std.range immediately after the struct. How is DMD supposed to know that that struct is suppose to be a range otherwise? -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
