Is it possible to dynamically create query descriptions based on a list of types?

[proc-gen]

My implementation seems like I'm really close, but not quite there and may be something I just don't know how to do.

Essentially, I have components that all inherit from an interface and I'd like to generate query descriptions based on a list of types.

var type = typeof(ISpell);
var types = AppDomain.CurrentDomain.GetAssemblies()
    .SelectMany(s => s.GetTypes())
    .Where(p => type.IsAssignableFrom(p) && !p.IsInterface);

foreach (var spellType in types)
{
    var spellQuery = new QueryDescription();
    spellQuery.All.Append(Component.GetComponentType(spellType));
    spellQueries.Add(spellQuery);
    componentTypes.Add(spellType);
}

for(int i = 0; i < spellQueries.Count; i++)
{
    var spellQuery = spellQueries[i];
    world.Query(in spellQuery, (in Entity entity, ref Position pos) =>
    {
        var spell = entity.Get(componentTypes[i]);
        ((ISpell)spell).Cooldown = processSpell(gameTime, entity, pos, (ISpell)spell);
        entity.Set(spell);
    });
}

When I try to do this, I get the following error:

Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

My guess is that it has to do with the way I'm passing spellQuery into world.Query.

Something like this would make it very easy for me to automatically have new spell components processed correctly, for example if I added Spell4, Spell5, and Spell6 in addition to the existing Spell1, Spell2, and Spell3. Same thing would apply with components I use for effects like Burn, Shock, and Slow.

[genaray]

Is this commited already? If so i would check it out real quick ^^

I assume that theres a conversion error somewhere. What type is the array ComponentTypes?

My assumption, it is : "Type[]" which is then being passed into the get? If so thats not valid and would produce such an error ^^

[proc-gen]

It made it through all the lines inside the query and it highlighted the entire world.Query when it threw the exception.

I just re-added it locally, but didn't check it in because of other things I'm working on. I updated it so the lists are the following:

List<QueryDescription> spellQueries = new List<QueryDescription>();
List<ComponentType> componentTypes = new List<ComponentType>();

And now populated via:

foreach (var spellType in types)
{
    var spellQuery = new QueryDescription();
    spellQuery.All.Append(Component.GetComponentType(spellType));
    spellQueries.Add(spellQuery);
    componentTypes.Add(Component.GetComponentType(spellType));
}

The reason I think it's passing spellQuery into world.Query is because it highlights the entire query for the exception and not a specific line.

[genaray]

Can you take a look at the "entity.Get()" method? Ts signature? Sometimes it happens that e.g. the generic methods are favored which is not what we want in this case ^^

The highlighting also occurs once an error inside that method is called, since most code gets inlined :)

Would be great if you could check it in on an other branch, that way i could debug it... If its an bug :)

[proc-gen]

I threw it up in this branch: https://github.com/proc-gen/roguelite-survivor/tree/generic-query-descriptions

Everything is in ~\Systems\AttackSystem.cs, and it'll fail as soon as you start a level. Hopefully you find something I'm not seeing :)

[genaray]

Gonna do that once im home! :)

[genaray]

Sooo i found the issue. Its not a bug, it was an logic mistake ^^

First of all, your spellQueries are... empty. No all, any or none set. I assume that your code to fill the doesn't work properly.
Thus each SpellQuery targets ALL entities.

Second, the world.Query trys to access ref Position position. Since the query targets ALL entities, it tries to receive the position from ALL of them (also entities without it) which throws that exception.

Use this instead for your spellQueries :

                var spellQuery = new QueryDescription
                {
                    All = new[] { Component.GetComponentType(spellType), typeof(Position) }
                };

So make sure the spellQueries are filling correctly and its fine ^^

[proc-gen]

I don't use arrays very often, so I guess my issue is that I assumed that using Append would add the component types I wanted to the existing array. I just looked at the function definition to find that it returns a reference to the new array, which explains why the queries were empty in my original version.

Edit: Just got these changes include in the main branch along with similar updates for status effects