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c#extension-methods
MiBol
MiBol

Reputation: 2125

C# How create a extension without parentheses

I have a weird question about C#.

I have a static class to store methods as extensions. Then, I have the following extension:

public static bool fwHasData(this DataTable table)
{
    return (table == null || table.Rows.Count == 0) ? true : false;
}

My question is: exists some way to avoid use the parentheses when I try to use the extension in my code?

Usage:

bool vHasData = MyDataTable.fwHasData(); // Works fine!

Expected usage:

bool vHasData = MyDataTable.fwHasData; // Removing the parentheses

Thanks a lot!

Upvotes: 4

Views: 1271

Answers (4)

Riegardt Steyn
Riegardt Steyn

Reputation: 5701

Well, I just accidentally did this (I was so surprised, I googled it and that led me here):

Func<IEnumerable<IPlanHeader>> test = header.AsEnumerable;

With this extension method:

public static class ExtendGenericType
{
    public static IEnumerable<T> AsEnumerable<T>(this T entity)
    {
        yield return entity;
    }
}

...and lo-and-behold, no parenthesis! So please try this, and let me know:

Func<bool> vHasData = MyDataTable.fwHasData;

EDIT - Look, ultimately you will still need to convert the Func<bool> to bool using parenthesis at some point:

bool hasData = vHasData();

Upvotes: 1

Manish Basantani
Manish Basantani

Reputation: 17509

As suggested by others, the limitation is you can not have an extension property!

but, for the sake of achieving what you want. You can create a class deriving from DataTable (DataTable class is not sealed) and use this derived version in all your code.

Then you can extend DataTable with as many properties as you want!

Example:

public class DataTableEx : DataTable
    {
        public bool fwHasData
        {
            get
            {
                return (Rows.Count == 0) ? true : false;
            }
        }
    }

Upvotes: 0

BradleyDotNET
BradleyDotNET

Reputation: 61349

No, this is not possible. Trying to call a method without parentheses doesn't make sense in C#.

You declared an extension method so of course you would need to call it as such (using the parenthesis).

You are accessing it as if it is an extension property which do not yet exist in C#. Regardless, you didn't declare it like a property, so even if they did exist you would still need to call it as a method.

Upvotes: 0

Reed Copsey
Reed Copsey

Reputation: 564433

This is not possible in C#. It would require some form of "extension property" syntax, which is not available in C#. It has been suggested in the past, but doesn't exist in the C# language today, nor in the upcoming C# 6 suggestions.

Upvotes: 10

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