On Wednesday, 29 April 2015 at 22:02:29 UTC, novice2 wrote:
Hello.
Help me please to understand, how to show usage help to user,
who enter wrong options?
For example, user not provided required filename.
I want to show error message, and program usage help text.
But likely getopt don't provide help text until valid options
will be parsed.
Reduced code:
///////////////
import std.stdio: writefln;
import std.getopt;
void main (string[] args)
{
string fname;
GetoptResult helpInfo;
try
{
helpInfo = getopt(
args,
std.getopt.config.required, "file|f", "File name",
&fname);
writefln("Options parsed: fname=%s", fname);
}
catch(Exception e)
{
writefln("\nERROR: %s", e.msg);
defaultGetoptPrinter("Program usage:", helpInfo.options);
}
}
///////////////
Output:
ERROR: Required option file|fwas not supplied
Program usage:
Also, I suggest you look at docopt:
http://code.dlang.org/packages/docopt
It makes the whole parsing of CLI arguments very nice and easy.