Default condition in Inline If statement

Question

I am fetching a database row inside my c# code. Row contains 3 different flags (3 columns with true or false values). Only one of these columns will be true and that will determine the type of that object. How can i determine the type of that object in one line of code. If all three flags are false then i need to have a default type.

var myObject = this.unitOfWork.myRepository.GetMeObject();

 var objectType = myObject .IsA == true
                              ? "A"
                              : myObject .IsB == true
                                    ? "B"
                                    : myObject .IsC == true
                                          ? "C"
                                          : "D";

If none of the condition is valid then ObjectType should be D

Any suggestion will be much appreciated.

Thanks

Apart from the readability, what's wrong with what you already have? — musefan, Jul 12 '13 at 09:51
`myObject.GetType().ToString()`? or did you want Activator.CreateInstance(myObject.GetType()); — Sayse, Jul 12 '13 at 09:51
Why do you need to know the type? Can they not share a common interface that lets you perform the operation you need to perform? — Fenton, Jul 12 '13 at 09:53
@Sayse and Steve, have you not read the question? OP has a database row, with different columns that determine the type — musefan, Jul 12 '13 at 09:54

musefan · Accepted Answer · 2013-07-12T10:07:43.877

5

Personally, I would be tempted to create an extension method for your database object. Something like this:

public static string GetObjectTypeOrDefault(this MyObject myObject)
{
    if(myObject.IsA) return "A";
    if(myObject.IsB) return "B";
    if(myObject.IsC) return "C";
    return "D";
}

Then you would use it like this:

MyObject myObject = this.unitOfWork.myRepository.GetMeObject();
string objectType = myObject.GetObjectTypeOrDefault();

You can even check for null objects with this method

If you still just want a single line, then you original attempt will work fine, but could be cleaned up a bit:

var objectType = myObject.IsA ? "A" : myObject.IsB ? "B" : myObject.IsC ? "C" : "D";

edited Jul 12 '13 at 10:07

answered Jul 12 '13 at 10:01

musefan

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it definitely *is* good practice, what would you do instead when you need a split in your code execution? – Sayse Jul 12 '13 at 10:12
@Sayse see this http://stackoverflow.com/questions/12685675/is-it-good-practice-use-more-that-one-return-statement-in-a-method – sangram parmar Jul 12 '13 at 10:16
1

@sangramparmar: The accepted answer that you posted specifically says it is fine in short examples. Also, this is one person's opinion - where is the evidence as to why it is bad practice? – musefan Jul 12 '13 at 10:18
@musefan - He is suggesting that you should assign a variable and then return that variable.. Half understand that. But at the same time, I believe your code here to be more efficient as you are performing multiple checks that will be redundant if object `IsA`. I prefer efficiency, if developers are going to get confused, you can add a comment to your method. – Sayse Jul 12 '13 at 10:21
ok see this http://stackoverflow.com/questions/708675/why-is-it-good-practice-to-return-at-the-end-of-a-method – sangram parmar Jul 12 '13 at 10:26
1

@sangramparmar: Again, the most upvoted answer says they don't support the view and will use which ever approach is right for the job. Fact is, I don't live my life by blindy following one rule I read somewhere back in the day. I will evaluate each problem for what it is, and choose what I believe to be the best solution. I know what you are suggesting to fix my method, and I would use a "result" variable in many case where the code flow is more complex. But in this instance my approach is much simpler. Can you honestly tell me one disadvantage of what I have done here? – musefan Jul 12 '13 at 10:29
1

@sangramparmar: Also, 489 voters agree with [this answer](http://stackoverflow.com/a/36714/838807). In fact, most of the answers on that thread say how acceptable multiple return points are. Including [this example](http://stackoverflow.com/a/36839/838807) of why blindly following such a silly rule can make code hard to read – musefan Jul 12 '13 at 10:33
@musefan - The only thing I found to support his point was [this](http://programmers.stackexchange.com/a/118717) but this does not apply to C#, SEME pattern for me – Sayse Jul 12 '13 at 10:42
@Sayse: While I agree that is an example of poor use of an early return. I would say the rule there is more "make sure you clean up" rather than "early returns are bad". An example in C# where this might occur is if we open a DB connection, and return before closing it. But that is just bad decision making on the coders part. Of course we can overcome this with the `using` block. However, I would never return early while I have a connection, or stream, or something else open. I think the overall point is, the so called rule has been created to reduce the amount of bugs that bad coders create – musefan Jul 12 '13 at 10:56
@musefan - I agree, that article just points out that programming languages can evolve faster than the programmer – Sayse Jul 12 '13 at 11:03

Adrian Wragg · Answer 2 · 2013-07-12T10:07:08.077

0

Not quite the same, as I'm aiming here for readability rather than efficiency; this may be easier to follow for future developers of your system:

var myObject = this.unitOfWork.myRepository.GetMeObject();

string objectType = (myObject.IsA ? "A" : "") +
                    (myObject.IsB ? "B" : "") +
                    (myObject.IsC ? "C" : "");

objectType = (objectType == "") ? "D" : objectType;

Or, as a slight less readable single-line version,

var myObject = this.unitOfWork.myRepository.GetMeObject();

string objectType = (myObject.IsA ? "A" : "") +
                    (myObject.IsB ? "B" : "") +
                    (myObject.IsC ? "C" : "") +
                    ((myObject.IsA || myObject.IsB || myObject.IsC) ? "" : "D");

edited Jul 12 '13 at 10:07

answered Jul 12 '13 at 09:56

Adrian Wragg

7,311
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This is exponentially less efficient – Sayse Jul 12 '13 at 09:59
Yes; it's posted here as an example of how the functionality could be made readable, which I felt was an issue with the other answer at the time this was written. – Adrian Wragg Jul 12 '13 at 10:02

sangram parmar · Answer 3 · 2013-07-12T10:03:15.687

-1

try this

            var objectType = ((myObject.IsA)
                                    ? "A"
                                    : ((myObject.IsB)
                                                    ? "B"
                                                    : ((myObject.IsC)
                                                                ? "C"
                                                                : "D")));

edited Jul 12 '13 at 10:03

answered Jul 12 '13 at 09:56

sangram parmar

8,462
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-1: Same logic that the OP already has, except you have made it harder to read. And you still kept the pointless `== true` checks – musefan Jul 12 '13 at 09:57
WIll this Return 'D' if none of the conditions is true? – InTheWorldOfCodingApplications Jul 12 '13 at 10:01
@user1711287: Your current code with return "D" if none of the condition is true already – musefan Jul 12 '13 at 10:02
working fine...if none of the condition true It will return D..@musefan – sangram parmar Jul 12 '13 at 10:03

Default condition in Inline If statement

3 Answers3