c# - Why can't I use System.ValueType as a generics constraint? -

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  • क्यों मैं की एक बाधा का उपयोग नहीं कर सकता जहां टी: System.ValueType ?
  • माइक्रोसॉफ्ट इस प्रकार से एक प्रतिबंध से क्यों रोकता है?

उदाहरण:

क्यों 'निम्न मैं क्या करूँ?'

<पूर्व> // एक। नेट वर्ग सार्वजनिक शून्य बार में परिभाषित & lt; T & gt; (टी ए) जहां टी: ValueType {...} // मेरी कक्षा में परिभाषित सार्वजनिक शून्य foo & lt; T & gt; (टी ए) जहां टी: मान टाईप {बार & lt; T & gt; (ए); }

ValueType पर स्ट्रैट का उपयोग करने में क्या अंतर है? 

  // मेरी कक्षा सार्वजनिक void foo में परिभाषित & lt; T & gt; (टी ए) जहां टी : संरचना {बार & lt; T & gt; (ए);

का उपयोग करने के बीच दो अंतर हैं 

  जहां टी: स्ट्रक्चर

और 

  जहां T: ValueType
  • बाद वाला हो <टी> हो T हो, जो कि एक संदर्भ प्रकार है।
  • बाद में T को एक नल योग्य मूल्य प्रकार

इन अंतरों में से सबसे पहले आप क्या चाहते हैं, लगभग कभी नहीं। दूसरा कभी-कभी उपयोगी हो सकता है; Nullable & lt; T & gt; में थोड़ा अजीब है, यह न तो जहां टी: struct और जहां T: class बाधा है

P> अधिक उपयोगी होगा constraint 

  जहां टी: struct, System.Enum

जो C # द्वारा कोई अच्छा कारण नहीं है कि मैं बता सकता है के लिए निषिद्ध है । इस पर अधिक देखें और इसके लिए।


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