Hi guys, apologies for the silly question, but I come from the world of dynamic languages and I'm wondering if it's possible to set struct values basic on dynamic variables?

e.g.

struct Person {
   string firstName;
   string lastName;
}

void main() {
   string[string] map;

   map["firstName"] = "Homer";
   map["lastName"] = "Simpson";
}

Is it possible to iterate through the hash map and set the struct values using the key/value pairs?

Something like this:

e.g.
Person p1;

foreach(key,val; map) {
   p1[key] = val;
}

The problem I'm trying to solve is that I'm wanting to write a generic "model" class that can read a record from a database and populate a known struct from the database values.  I have seen the "allMembers" method from the traits module that can give me the names of the struct fields, but I am unsure if it's even possible to set the struct values using variable/dynamic names.

Any help will be greatly appreciated!
Cheers,
Andrew.

On Thursday, 12 May 2016 at 20:52:46 UTC, Andrew Chapman wrote:
> I have seen the "allMembers" method from the traits module that can give me the names of the struct fields, but I am unsure if it's even possible to set the struct values using variable/dynamic names.


Yes.

You can't loop over the hash and set values on the struct, since looping a hash is a run time operation, but you can loop over struct members.

So, the trick is to loop over the struct members (a compile-time operation) and set them (converting type with `std.conv.to` if necessary) if the value is in the hash.

foreach(member; __traits(allMembers, YourStruct))
  if(member in yourhash)
   __traits(getMember, your_object, member) = to!right_type(yourhash[member]);


basically, it is a bit more complex to filter out inappropriate fields and such, but that's the idea.

Check out the sample chapter of my book https://www.packtpub.com/application-development/d-cookbook to see more, you can get the reflection chapter free on that site.

On Thursday, 12 May 2016 at 21:01:06 UTC, Adam D. Ruppe wrote:

> foreach(member; __traits(allMembers, YourStruct))
>   if(member in yourhash)
>    __traits(getMember, your_object, member) = to!right_type(yourhash[member]);
>
>
> basically, it is a bit more complex to filter out inappropriate fields and such, but that's the idea.
>
> Check out the sample chapter of my book https://www.packtpub.com/application-development/d-cookbook to see more, you can get the reflection chapter free on that site.

That's wonderful Adam, thank you!  I actually had your book previously bookmarked - I should probably buy it :-)