On Tuesday, 20 July 2021 at 21:18:12 UTC, Bagomot wrote:
But there is a problem with different types. I understand that
Object[] is not suitable here, but I don’t know how to do it.
I ask you to help me with this.
IIUC, the `arguments` are command line arguments passed to a Java
program, and some of those might be passed to the JVM ?
So you probably will end up with something like:
```
struct Arguments{
JVMArgs jvm;
ProgramArgs program;
}
```
Of course, the question is, what's `JVMArgs` ?
Now, as you noticed, you can't represent an array of unrelated
types in D (which makes sense). So what you can do is create a
common type for it, by using an `union`.
```
union JVMArg
{
RuleValue ruleValue;
string str;
// Etc...
}
alias JVMArgs = JVMArg[];
```
However, \<YOUR-JSON-LIBRARY> might not support it directly, or
might support it through its own type (you will need a tagged
union, and not just a simple union, as you need to know the type
that the library read).
But if you take a step back, I think you might find this solution
is far from ideal.
Having worked on a JSON library myself, I can tell you they are
all implemented with a tagged union. And converting a tagged
union to a tagged union is no improvement.
Instead, I would recommend to just use the JSON directly. If you
need to pass things around, you might want to deserialize it to a
common format. For example, assuming your project is a process
manager for Java program and you want to read a common set of
arguments from a configuration file, you might want to just
generate the strings:
```
auto myJSON = parseConfigFile("config.json");
string[] defaultJVMArgs = parseJVMArgs(myJSON);
auto processMonitor = new ProcessMonitor(defaultJVMArgs);
```
TL;DR: If you want to use loosely typed data in a strongly typed
language, you need to come up with a common type. That common
type is usually either a discriminated union (which a JSON object
is, essentially) or something that is domain-specific.
Hope this helps. I had a quick look at asdf and couldn't see a
support for tagged union, so you would probably need to provide
your data structure with a `deserializeFromAsdf` method. If you
want to do so, look into providing a wrapper to `SumType`, e.g.:
```
struct MyUnion (T...) {
SumType!T data;
alias data this;
SerdeException deserializeFromAsdf(Asdf data) { /* Fill in
the SumType */ }
```
But I would recommend just using the JSON object if you can.
