Member Avatar for LoLFactor

I'm interested in making an .ini file parser and I want it to have an internal list that can hold it's individual entries. The catch is I want to make one list to hold all the values. That means strings, boolean values and int types.

I have a class to hold key-value pairs that is a template.

public class KVPair<T>
{
    private string key;
    private T      value;
...
}

I'm interested to know if there's any way to make a list something like

List<KVPair> something;

without having to specify a certain type for the inner object, or a work-around.

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  • Latest Post Latest Post by Momerath

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Generated

The build error comes from how C# generics work: a closed generic type like KVPair<string> is a different, incompatible type from KVPair<object>. That’s why storing mixed KVPair<T> instances directly in one List<T> fails. is right that boxing everything as object works but forces external casts; is right to call out invariance and section semantics for INI files.

A practical pattern that keeps type info and avoids external casts is a non-generic abstraction plus a generic implementation. For example, expose a non-generic interface for consumers and implement it with your generic KVPair<T>; store a List of the interface. The interface provides an object Value and a Type (or a generic TryGet<T> helper) so callers can request a typed value without knowing the concrete T at compile time.

public interface IEntry {
  string Key { get; }
  object Value { get; }
  Type ValueType { get; }
  bool TryGet<T>(out T val);
}

public class Entry<T> : IEntry {
  public string Key { get; set; }
  public T Typed { get; set; }
  public object Value => Typed;
  public Type ValueType => typeof(T);
  public bool TryGet<TOut>(out TOut val) { ... } // use "is" or ChangeType
}

Alternative: keep the raw INI text and offer parsing accessors (e.g., TryGetInt, TryGetBool, TryGet<T> using TypeConverter/Convert.ChangeType). This is simplest for INI-style data and preserves the original string (useful for comments/round‑trips). Covariant interfaces (IKVPair<out T>) are possible but only help for reference types, not value types like int/bool.

Other practical tips: key your storage by section+key (nested dictionary), cache parsed values if parsing cost matters, and prefer Try-patterns to avoid exceptions when parsing fails. This keeps the API ergonomic while preserving type information and encapsulation.

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Member Avatar for Kimpl

Generally you could just do:

List<object> anything = new List<object>();

The issue is you'd need to know what the values are, so that you could cast them as specific types when you need to:

string name = (string)anything[0];

Hope that helps.

Member Avatar for LoLFactor

I don't want to sound pompous, but I was hoping for something more elegant, since casting to a key-value pair outside the file handler class defeats the whole purpose of encapsulating the data into a class.
For some reason this

List<KVPair<object>> something;

doesn't work. In the build errors it sais:
"Cannot convert type 'KVPair<object>' to 'KVPair<string>'"
when I try to add a KVPair<string>.

Member Avatar for Momerath

The user of your class will need to know what type is being returned, or else how are they going to use it? They will have to know to expect a string, boolean, int, etc. Sure, they could assign it to var, but then what good is it? Should you add something to it, or parse it as a string or test the true/false value?

You are going to have to cast (easy way) or use a struct to hold the values and create a 'union' type (like the one in C). is an article about creating a union type for C#.

As for your error, a KVPair<object> is a different type than a KVPair<string>, with no method defined to cast it, so you get an error. Don't be confused by the <object> part, remember it's a KVPair<T>.

You also need to consider that ini files have sections, and it's perfectly fine to have the same key in multiple sections. For example

[Standard]
User=Bob

[Specific]
User=Fred

So a simple dictionary of key/values won't work.

Edited by Momerath because: n/a
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