On Friday, 18 September 2015 at 11:54:32 UTC, Robert burner
Schadek wrote:
On Friday, 18 September 2015 at 11:35:45 UTC, John Colvin wrote:
Posting here instead of learn because I think it uncovers a
design flaw
void main(string[] args)
{
import std.file : dirEntries, SpanMode;
import std.stdio : writeln;
foreach(file; dirEntries(args[1], SpanMode.depth))
writeln(file.name);
}
Modify this program such that it will print "<file.name>
access denied" instead of crashing with an exception whenever
it hits a permissions problem. Remember that you might not
even have permission to read the directory given in args[1].
Remember that access permissions can change at any time.
It can be done, but it is seriously ugly.
http://dlang.org/phobos/std_exception.html#.handle
foreach(file; dirEntries(args[1], SpanMode.depth)
.handle!(Exception, RangePrimitive.front, (e, r) =>
DirEntry())) {
writeln(file.name);
}
change Exception to the Exception Type to handle and select the
throwing range primitive (RangePrimitive). Then just supply a
delegate that does the actual handling.
This will not break any range chain!
That's neat, didn't know about std.exception.handle
Unfortunately, I think there are two problems with your solution:
1) DirIteratorImpl will throw on popFront, not front. I had to
look at source to find out. Is this a failure of documentation or
is it actually an implementation detail?
2) it doesn't cover the case where args[1] itself is unreadable,
because dirEntries will throw when it's created.
