Since cstream is deprecated and stdio.readf is finally available with
2.048, I started modifying my D book by replacing code like
T var;
din.readf(&var);
with
T var;
readf("%s", &var);
1) I couldn't go far, because stdio.readf does not ignore whitespace and
code like the following fail:
int i;
int j;
readf("%s", &i);
readf("%s", &j);
When the input is
42 43
the output is
std.conv.ConvError: std.conv(1070): Can't convert value
`LockingTextReader(File(807637C), )' of type LockingTextReader to type int
[...]
Is that by design? Should the users strip the input themselves?
2) This is not a show stopper, but having to provide a format string for
simple value input is unnecessary. It makes D less suitable for
programming novices. (I see D very easy for novices in general,
especially compared to C and C++.)
3) We need a simple way of reading values from stdin if only for the novice.
Another solution is using string.strip and conv.parse:
auto line = strip(stdin.readln());
auto i = parse!int(line);
auto d = parse!double(line);
but that requires importing std.string and std.conv in addition to
std.stdio. Also, with that, both of the values must be on the same line.
A novice should be able to read as simple as
auto d = read!double();
auto i = read!int();
Ignoring stripping whitespace, read can be implemented like this:
T read(T)()
{
T value;
readf("%s", &value);
return value;
}
Actually stream.readf's signature was also nice. Can we do the same with
stdio.readf?
readf(&v0, &v1, &v2);
Ali
