How
are Generics of C# (C Sharp) Different from C++ Templates
C# Generics
and C++ Templates share a commonality that they deal with types that are
parameterized. You need not define the type readily; it can be determined
and supplied at a later point of time. Though their intension is same,
they both have a couple of differences as well. This article will give
you an overview on the differences between C# generics and C++ templates.
Given below
is a chart highlighting the difference between C# generics and C++ templates.
The chart contains list of tasks. If the task is applicable to either
C++ templates or C# Generics, a tick mark is shown in the appropriate
column. If the task is not applicable, then a cross mark is shown.
Task C++
Templates C# Generics
Usage of Operators (Both Arithmetic and User Defined) ? X
Explicit Specialization ? X
Partial Specialization ? X
Default Types Associated with Parameterized Type ? X
Define and Use Template Parameters ? X
Define and Use Non-template Parameters ? X
Use Lazy Structural Constraints ? X
Directly Inherit From Type Parameter ? X
Use Reflection to Provide Run Time Support X ?
Strong Type Checking X ?
Define and Enforce Constraints on Parameterized Type X ?
Mention Valid Operations at the Time of Definition X ?
Display of Better Error Messages X ?
Option to Specify Parameterized Type to Implement a Specific Interface
X ?
Flexibility to Use in a Cross Library and Cross Language Fashion X ?
Other
Differences:
C++ Templates
C# Generics
Instantiation is done at compile time. Instantiation is done at run time.
In C++ templates, each type associated with the template will have an
individual class definition irrespective of whether it is an object type
or value type. At the time of compilation, all the object types share
a single class definition and an independent class definition is provided
for each of the value type.
When you instantiate C++ template, during compilation time entire content
of the template will be copied in the place of instantiation. If ten instances
of the template are used in different places of code, then ten copies
of the template code will be pasted in those places. No such textual expansion
happens.
You cannot create any dll or reusable component containing these templates
which can be reused at a later point of time. You can create generic dll
containing generic class. This generic dll can be used across various
projects.
C++ templates are similar to macros. Both undergo textual expansion during
compilation. C# Generics are similar to classes except that generics accept
parameterized types whereas classes don’t.
Type identity of specialization is unique for each assembly. C# Generics
provide globally unique type identity of specialization.
Name lookup is done at the time of specialization. Name lookup is done
at the time of definition.Binding to type. Binding to constraints.
