I still think the "var" in C# is a really bad idea

[dazfuller]

Agreed, in a typed language what's the point of not defining the type? If you don't want to define the type then use Python

[Stuart Dootson]

The specification of MyMath.Add is part of the code, right? So read that bit... And whatever you do, don't use a language like Haskell or Ocaml, which does real, powerful type deduction - it'll blow your mind...

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p CodeProject MVP for 2010 - who'd'a thunk it!

[Adriaan Davel]

I like var because it takes focus off the type, and places it on the variable name. With a good variable name var actually improves your code if you were to change the type later. Consider: int customerBalance = GetCustomerBalance();, which has to be changed to decimal customerBalance = GetCustomerBalance(); after the function return is changed, where var customerBalance = GetCustomerBalance(); would have worked both ways. If you have enough dicipline in variable names one wouldn't need to look at the types (mostly), and var promotes this (to a degree).

____________________________________________________________ Be brave little warrior, be VERY brave

[Henk Nicolai]

Agreed... So why don't we have some kind of Visual Studio option that does all the type-inference and replaces all those 'var's with actual inferred types? I thought the main purpose of 'var' was to increase productivity... Or, maybe the following syntax should be allowed: Dictionary<string> myDictionary = new(StringComparer.OrdinalIgnoreCase); (E.g. no extra type declaration if selecting a constructor from the same class. Not very readable though if you're not used to it.) - DerHenker

[Alexander DiMauro]

.jpg wrote:

var num = MyMath.Add( 123, 789 );

Once again, your example is a perfect example of PEBKAC, and not an example of a problem with var. If used as intended, 'var' is extremely useful. Your example is NOT an intended use. While it can be done, you are absolutely correct. You don't know what the return value will be. But, when used with LINQ, it is EXTREMELY useful, and that was really its intended purpose. It can also help in situations like this: SomeInsanelyLongNameThatNeverEnds<LongLongName, SuperLongNameAgain> someVar = new...you get the picture. Throw a var in there and it shortens it considerably without losing any information. That is really, IMHO, the only time to use var outside of LINQ, when you don't lose any information. The final point is...get ReSharper. If you are unsure of return values, but want to display them, type in 'var', and then select 'specify type explicitly' in ReSharper, and it puts the return type in there for you. VERY useful! I use that one all the time.

[Filip Duyck]

Code is written once and read many times. Why force the reader to read the same information twice? On top of that, using 'var' somewhat forces people to pick more meaningful names, and it makes refactoring easier. Of course, that is only my opinion. You're entitled to yours, and I'm sure many people would agree with you.

[Lost User]

Let's name it DIM!

I are Troll :suss:

[Fabio Franco]

I think its a really bad idea too. It opens the doors to all kind of bad/lazy code. Poor testers, reafactores, inheritors... It's even worse with the introduction of dynamic keyword, which flushes type safety down the toiled. I see .net going downhill. :~

[Lost User]

Marc Clifton wrote:

I still don't see the purpose of var except for Linq and/or lambda expressions.

Then don't use it. -Max

[Marc Clifton]

Max Peck wrote:

Then don't use it.

I don't. :) But somewhere in this morass of opinions, there ought to be some actual way of determining best practices, and that's what I keep trying to figure out. Marc

[Ed K]

Because there are still those using Re-factor who right click and change all to 'var' as a first step to obfuscating their code.

ed ~"Watch your thoughts; they become your words. Watch your words they become your actions. Watch your actions; they become your habits. Watch your habits; they become your character. Watch your character; it becomes your destiny." -Frank Outlaw.

[Lost User]

Marc, Best practices? From this group? Are you nuts? :laugh: You'll definitely get some good input from the guys here but "best practices" is something I've never even see an organized company maintain without great difficulty let alone a forum of rogue programmers like us! Don't tell me you don't still use GOTO. ;-) -Max

[martinluch]

Some times you dont want to create a class to expose only a couple of properties. What do you think about this code...

// Build an anonymous type
var anon1 = new { number = 4, square = 4 * 4 };
// Do something with it
Console.WriteLine(string.Format("Square of {0} is {1}", anon1.number, anon1.square));

or...

List<object> myList = new List<object>(); // Build a new collection
for (int i = 0; i < 5; i++)
{
var anon = new { number = i , square = i * i }; // Build an anonymous type
myList.Add(anon); // Start adding anonymous types to it
}

foreach (var anonymousType in myList)
{
PropertyInfo[] MyProperties = anonymousType.GetType().GetProperties(); // Reflect the type

    foreach (var Property in MyProperties) 
    {
    	Console.WriteLine(Property.GetValue(anonymousType, null).ToString()); // Do what you want with the property
    }

}

Useful or not? Up to you...

[John Oxley]

But you still have to type in the type the first time round. Plus the line is longer and more cumbersome to read.

[Marc Clifton]

John Oxley wrote:

Plus the line is longer and more cumbersome to read.

I must read code differently from other people. I've never noticed that the "old" style is cumbersome! Marc

[John Oxley]

var does compile time inference of the type. It looks at the right hand side of the equals and says, ah that's a string therefore that's what I shall be. Not an int. Not a double. Not even shall I pretend to be a DateTime. The day that someone tries to made me a TcpClient, I shall have my trusty compiler beat thee with a stick.

var transaction = repository.GetTransaction(id);

I'm guessing that transaction is going to be of the type AKittyLitter. Yes that makes sense. Oh and id is the name of my CEO's pet gerbil. (If you use Notepad / vim / anything else stupid, I'm not talking to you) You're working in Visual Studio, not nano. Use it.

var x = y.Foo();

The bloke who actually has that in his release project should be shot. I agree with a previous poster that your variable names and method names should mean something. If repository.GetTransaction doesn't return a Transaction object, then I've designed my code stupidly. If Transaction doesn't have a decimal Amount property on it, well, then Visual Studio will tell you before the 3rd letter. Go read this: http://omergertel.com/2010/07/04/how-to-read-code/[^]

[dazfuller]

What's more useful though is if a maintainer can do read-the-code time inference of the type. If y.Foo() returned a NappySack object then they can go have a look at that type and figure out what it can do. With a var they'd have to go and look at the y.Foo() to figure out what is returned and then figure it out from there. And I don't want my compiler having to figure this out, it takes it long enough as it is already to do anything useful and I can only spend so much of my day making cups of coffee!

[AspDotNetDev]

Pft, why even specify a type? Check out what this person has to say.

[Forum Guidelines]

[Todd Smith]

Ed K wrote:

Because there are still those using Re-factor who right click and change all to 'var' as a first step to obfuscating their code.

I guess that's their problem then isn't it :)

Todd Smith