Recently had a discussion with a fellow dev regarding the difference between typeof(T).Name and nameof(T).
It is a lot more performant to use nameof keyword if you are just trying to get the string name of type as opposed to typeof(T).Name.
Let's look at an following example.
Given a simple C# console app as follows:
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class Program
{
static void Main(string[] args)
{
Console.WriteLine(typeof(Program).Name);
Console.WriteLine(nameof(Program));
}
}
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The compiler generates the following IL:
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.method private hidebysig static void Main(string[] args) cil managed
{
.entrypoint
.maxstack 8
IL_0000: nop
IL_0001: ldtoken typeof_nameof.Program
IL_0006: call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle(valuetype [mscorlib]System.RuntimeTypeHandle)
IL_000b: callvirt instance string [mscorlib]System.Reflection.MemberInfo::get_Name()
IL_0010: call void [mscorlib]System.Console::WriteLine(string)
IL_0015: nop
IL_0016: ldstr "Program"
IL_001b: call void [mscorlib]System.Console::WriteLine(string)
IL_0020: nop
IL_0021: ret
}
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Notice nameof is turned into a string "Program"? while typeof(Program).Name generated code to execute get_Name(). typeof is definitely a runtime evaluation.
Naturally string literal requires almost zero calculation at runtime therefore it is a more performant one. In conclusion, we should favor it over typeof(T).Name
