Help: How to set property by string?

[jptang2]

As an EnTT beginner, I want to dynamically set component properties using strings. For example, how can I set registry.get<velocity>(entity).dx = x; when I only have:

The entity
Component name as "velocity"
Property name as "dx"
The target value of dx

Please help, thanks.

[skypjack]

You should use a reflection system for that. EnTT offers meta. The web offers many others. 🙂

[jptang2]

@skypjack Thank you for your quick response, I would like to try entt meta, but I noticed the wiki doesn’t clearly explain how to access components for a specific entity. Currently, I can set component properties using code like this:

registry.emplace<velocity>(entity, 0);
entt::meta_factory<velocity>{}.type("velocity"_hs).data<&velocity::dx>("dx"_hs);

auto type = entt::resolve("velocity"_hs);           // replaced by string
auto prop = type.data("dx"_hs);                        // replaced by string
auto velocityComponent = registry.get<velocity>(entity); // how to replace by "velocity"
prop.set(velocityComponent, propertyValue);                  // set dx to a given value

How to get velocityComponent from a given entity by string? I’d greatly appreciate your help.

[skypjack]

Ironically, I'm working on something similar in EnTT. It can probably help you.
See here for details. In particular, look at these lines:

const auto range = registry.storage();
internal::present_entity(ctx, entt, range.begin(), range.end());

Where a range of storage is provided to the present_entity function. If you check its body, it uses meta to get the job done.