C# Get Access Properties

Question

I would like to call function attribute (and also type) by it's name.

In python this goes something like this:

import time

method_to_call = getattr(time, 'clock') #  time.clock()
result = method_to_call()
print(result)

But what about C# and types? I want to use sizeof on converted ITEM_STRING_TO_TYPE. Is it even possible in C#?

List<string> mainList = new List<string>(new string[]
{
    "bool",
    "byte",
    "char",
    "decimal",
    "double",
    "float",
    "int",
    "long",
    "sbyte",
    "short",
    "uint",
    "ulong",
    "ushort"
});
foreach (string item in mainList)
{
    Console.WriteLine("Size of {0} : {1}", item, sizeof(ITEM_STRING_TO_TYPE));
    // like this
    Console.WriteLine("Size of int: {0}", sizeof(int));
}

In C# it is called reflection, I try to avoid it because of performance issue. Can't you do it by calling the method directly and passing arguments as it needs! — Burim Hajrizaj, Feb 12 '19 at 14:24

score 3 · Accepted Answer · answered Feb 12 '19 at 14:29

if by ITEM_STRING_TO_TYPE, you mean a Type, then there are a few problems here:

the .NET API is mostly .NET-based; int, long etc are not .NET names - they are C# aliases (and .NET targets multiple languages); this means that you'd need a language-specific map between the alias and a Type (the .NET names here are System.Int32 and System.Int64 respectively)
sizeof cannot be used with a Type; there is Unsafe.SizeOf<T>(), but that also cannot be used directly with a Type - it requires generics, so you'd need reflection via MakeGenericMethod
put those together, and it really won't be worth it - you'd do better to just hard-code the values; or just use a tuple array:

List<(string name, int size)> mainList = new List<(string,int)>(new []
    {
        ("bool", sizeof(bool)), 
        // ...
        ("ushort", sizeof(ushort)), 
    });

then you can use:

foreach (var item in mainList)
{
    Console.WriteLine("Size of {0} : {1}", item.name,  item.size);
}

or:

foreach ((var name, var size) in mainList)
{
    Console.WriteLine("Size of {0} : {1}", name, size);
}

Since the list is hard-coded, the OP's approach initializing the list with an array seems over complicated. I would directly initialize the list with collection initializer or simply use an array (as it's unlikely that its size will change). — Olivier Jacot-Descombes, Feb 12 '19 at 14:38
@OlivierJacot-Descombes yeah, agreed; it could just be `var mainList = new[] {...};` — Marc Gravell, Feb 12 '19 at 14:40

C# Get Access Properties

1 Answers1