C#:通过异构字典公开类型安全 API [英] C#: Exposing type safe API over heterogeneous dictionary
问题描述
我想通过特定的 JSON 格式公开类型安全的 API.到目前为止,这基本上是我所拥有的:
I'd like to expose a type safe API over a particular JSON format. Here is basically what I have so far:
public class JsonDictionary
{
Dictionary<string, Type> _keyTypes = new Dictionary<string, Type> {
{ "FOO", typeof(int) },
{ "BAR", typeof(string) },
};
IDictionary<string, object> _data;
public JsonDictionary()
{
_data = new Dictionary<string, object>();
}
public void Set<T>(string key, T obj)
{
if (typeof(T) != _keyTypes[key])
throw new Exception($"Invalid type: {typeof(T)} vs {_keyTypes[key]}");
_data[key] = obj;
}
public dynamic Get(string key)
{
var value = _data[key];
if (value.GetType() != _keyTypes[key])
throw new Exception($"Invalid type: {value.GetType()} vs {_keyTypes[key]}");
return value;
}
}
可以很好地用作:
JsonDictionary d = new JsonDictionary();
d.Set("FOO", 42);
d.Set("BAR", "value");
但是读取值有点令人失望,并且依赖于后期绑定:
However reading the value is a little disapointing and rely on late binding:
var i = d.Get("FOO");
var s = d.Get("BAR");
Assert.Equal(42, i);
Assert.Equal("value", s);
是否有一些 C# 魔法可以用来实现类型安全的泛型 Get<T>
而不是在这里依赖 dynamic
(理想情况下应该在编译时间)?我还想使用 Set
的模式,以便 d.Set("BAR", 56);
触发编译警告.
Is there some C# magic that I can use to implement a type-safe generic Get<T>
instead of relying on dynamic
here (ideally type should be checked at compilation time) ? I'd like to also use the pattern for Set<T>
so that d.Set("BAR", 56);
triggers a compilation warning.
字典<字符串,类型>如果需要,可以将 _keyTypes
设为 static
.以上只是正在进行中.
Dictionary<string, Type> _keyTypes
can be made static
if needed. The above is just work in progress.
推荐答案
我正在使用类似的解决方案:
I was using solution similar to this:
public class JsonDictionary
{
public static readonly Key<int> Foo = new Key<int> { Name = "FOO" };
public static readonly Key<string> Bar = new Key<string> { Name = "BAR" };
IDictionary<string, object> _data;
public JsonDictionary()
{
_data = new Dictionary<string, object>();
}
public void Set<T>(Key<T> key, T obj)
{
_data[key.Name] = obj;
}
public T Get<T>(Key<T> key)
{
return (T)_data[key.Name];
}
public sealed class Key<T>
{
public string Name { get; init; }
}
}
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