Источник:
http://dev.goshoom.net/en/2020/05/is...h-net-objects/
==============
I recently ran into an unfortunate limitation of .NET Interop from X++ (in D365FO).
I wanted to check if an X++ object is of a given type, nevertheless the type used for the variable declaration was a .NET interface. Here is an example:
using Microsoft.Dynamics.ApplicationSuite.FinancialManagement.Currency.Framework; void demo(IExchangeRateProvider _provider){ if (_provider is ExchangeRateProviderCBOE) {}}
Exchange rate providers are X++ classing implementing
IExchangeRateProvider interface and I wanted to check if the object I received was a particular provider (namely
ExchangeRateProviderCBOE class or its child). Unfortunately this ended up with a compilation error:
The operand on the left side of the ‘is’ or ‘as’ operator must be a table, class, or form.
As I tested, neither managed interfaces nor managed classes (such as
System.Object) can be used on the left side of ‘is’ and ‘as’ operators.
I solved the problem by using
Type.IsAssignableFrom() method. Simply using the ‘is’ operator would be nicer, but this does the job too.
void demo(IExchangeRateProvider _provider){ System.Object providerObj = _provider; if (providerObj.GetType().IsAssignableFrom(new ExchangeRateProviderCBOE().GetType())) {}}
Note that the problem is only with the left side of the operators, e.g. when you want to check whether a managed type is this or that. Using the ‘is’ operator to check if an instance of an X++ class implements a managed interface works without problems.
Object obj = new ExchangeRateProviderCBOE();if (obj is IExchangeRateProvider) {}
Источник:
http://dev.goshoom.net/en/2020/05/is...h-net-objects/