Add mp_length slot for .NET classes implementing ICollection/ICollection<T> #994
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- Checks if the object implement ICollection or ICollection<T> - Adds tests for explicit and non-explicit interface implementation
lostmsu
reviewed
Nov 21, 2019
Codecov Report
@@ Coverage Diff @@
## master #994 +/- ##
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Coverage 86.71% 86.71%
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Files 1 1
Lines 301 301
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Hits 261 261
Misses 40 40
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amos402
reviewed
Nov 21, 2019
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| // now look for things that implement ICollection<T> directly (non-explicitly) | ||
| PropertyInfo p = clrType.GetProperty("Count"); | ||
| if (p != null && clrType.GetInterfaces().Any(x => x.IsGenericType && x.GetGenericTypeDefinition() == typeof(ICollection<>))) |
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Too many reflections every times, you can try like this.
class Program
{
interface ICountGetter
{
int GetCount(object obj);
}
class CountGetter<Cls, T> : ICountGetter
{
private Func<Cls, int> _getter;
public CountGetter(Func<Cls, int> getter)
{
_getter = getter;
}
public int GetCount(object obj)
{
return _getter((Cls)obj);
}
}
static void Main(string[] args)
{
var obj = new MyClass();
var type = obj.GetType();
var declType = type.GetInterfaces().FirstOrDefault(
t => t.IsGenericType
&& t.GetGenericTypeDefinition() == typeof(ICollection<>));
if (declType == null)
{
// set error and return
}
var pi = declType.GetProperty("Count");
var elemType = declType.GenericTypeArguments[0];
var getterType = typeof(CountGetter<,>).MakeGenericType(declType, elemType);
var getterFuncType = typeof(Func<,>).MakeGenericType(declType, typeof(int));
var getterFunc = Delegate.CreateDelegate(getterFuncType, pi.GetMethod);
var getter = (ICountGetter)Activator.CreateInstance(getterType, getterFunc);
// You should cache the ([decltype] = getter), it makes you no reflection costs when you call GetCount next time.
int count = getter.GetCount(obj);
Console.WriteLine(count);
}
}There was a problem hiding this comment.
I agree, but I feel like it would be good to have feature + tests first. It can be optimized later.
lostmsu
requested changes
Nov 23, 2019
lostmsu
approved these changes
Nov 25, 2019
|
Thanks a lot for your contribution :) |
AlexCatarino
pushed a commit
to QuantConnect/pythonnet
that referenced
this pull request
Jun 27, 2020
…ion<T> (pythonnet#994) - Add mp_length slot implementation for .NET types - Check if the object implement ICollection or ICollection<T> - Add tests for explicit and non-explicit interface implementation
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What does this implement/fix? Explain your changes.
Implements the mp_length slot for .NET classes that implement ICollection or ICollection, either explicitly or non-explicitly.
Does this close any currently open issues?
There are no open issues relating to this as far as I know.
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Check all those that are applicable and complete.
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