If this technique is still valid, I need the code modernized so
that it works without warnings. I'm still in the D learning
curve, so I don't quite know what is being warned, and how to
clean up the mess.
I believe that the new code runs properly, but it would be nice
for it to be 'warning free'.
The prior source/app.d which runs is
```
import std.stdio;
import std.concurrency;
import std.conv;
struct CalculationFailure
{
string reason;
}
struct Exit
{
}
void calculate()
{
bool isDone = false;
while (!isDone)
{
receive((string message) {
try
{
ownerTid.send(to!double(message) + 0.5);
}
catch (Exception exc)
{
ownerTid.send(CalculationFailure(exc.msg));
}
},
(Exit message) { isDone = true; });
}
}
void main()
{
Tid calculator = spawn(&calculate);
calculator.send("1.2");
calculator.send("hello"); // ← incorrect input
calculator.send("3.4");
calculator.send(Exit());
foreach (i; 0 .. 3)
{
writef("result %s: ", i);
receive(
(double message) { writeln(message); },
(CalculationFailure message) {
writefln("ERROR! '%s'", message.reason);
});
}
}
```
When run, this is the output:
```
result 0: 1.7
result 1: ERROR! 'no digits seen for input "hello".'
result 2: 3.9
```
The goal is to modify source/app.d so that it includes this
snippet
```
// ... at the worker ...
try {
// ...
} catch (shared(Exception) exc) {
ownerTid.send(exc);
}},
// ... at the owner ...
receive(
// ...
(shared(Exception) exc) {
throw exc;
});
```
The new merged source/app.d for main() is
```
void main()
{
Tid calculator = spawn(&calculate);
calculator.send("1.2");
calculator.send("hello"); // ← incorrect input
calculator.send("3.4");
calculator.send(Exit());
foreach (i; 0 .. 3)
{
writef("result %s: ", i);
// ... at the owner ...
receive(
(double message) { writeln(message); },
// (CalculationFailure message) {
// writefln("ERROR! '%s'", message.reason);
// },
(shared(Exception) exc) {
throw exc;
}
);
}
}
```
The console output is:
```
c:\dev\D\81 -
90\c85_7d_exceptions_catch_send_exception_to_owner\source\app.d(26): Deprecation: can only catch mutable or const qualified types, not `shared(Exception)`
catch (shared(Exception) exc)
^
c:\dev\D\81 -
90\c85_7d_exceptions_catch_send_exception_to_owner\source\app.d(56): Deprecation: cannot throw object of qualified type `shared(Exception)`
throw exc;
^
c:\dev\D\81 -
90\c85_7d_exceptions_catch_send_exception_to_owner\source\app.d(26): Deprecation: can only catch mutable or const qualified types, not `shared(Exception)`
catch (shared(Exception) exc)
^
c:\dev\D\81 -
90\c85_7d_exceptions_catch_send_exception_to_owner\source\app.d(56): Deprecation: cannot throw object of qualified type `shared(Exception)`
throw exc;
^
result 0: 1.7
result 1:
std.conv.ConvException@C:\D\dmd2\windows\bin64\..\..\src\phobos\std\conv.d(3360): no
digits seen for input "hello".
```
