Bug 6993 – File.byLine runs on an empty file, fails enforcement

Create a new file "empty.d" and run this: import std.stdio; void main() { auto file = File("empty.d", "r"); foreach (aLine; file.byLine) { } } object.Exception@D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\stdio.d(943): Enforcement failed Line 943: enforce(file.isOpen); So the file was not successfully opened, but why wasn't an exception thrown in the File constructor then?

I don't see any reason why an exception would be thrown from File's constructor for an empty file. It certainly doesn't say that it does. The problem is that ByLine clearly isn't set up to handle empty files correctly. Duplicate of Bug# 6944 *** This issue has been marked as a duplicate of issue 6944 ***

(In reply to comment #1) > I don't see any reason why an exception would be thrown from File's constructor > for an empty file. It certainly doesn't say that it does. The problem is that > ByLine clearly isn't set up to handle empty files correctly. > > Duplicate of Bug# 6944 > > *** This issue has been marked as a duplicate of issue 6944 *** I agree, but the file handle was closed so I *assumed* that meant the file was not opened. I would rather have byLine not iterate than throw just because a file is empty.

Oh. I agree completely. I think that byLine should just be empty when the file is empty, so no iteration occurs. I don't know what the exact details of opening the file are, but I don't see why an empty file should throw when you try and open it. Certainly, File's docs don't say anything of the sort. In Linux however, I ended up hitting an assertion rather than the exception that you hit, so there may be system-dependent behavior going on.