Nullable boolean value with property

Question

Our Sonar code analysis server tells me

Boolean literals should not be redundant. Redundant Boolean literals should be removed from expressions to improve readability. Tag: Clumsy

and categorizes it as a minor bug.

Is this an error in the associated Sonar/FXCop C# rule (maybe it cannot handle nullable types?!) or is this really clumsy?

Note: createMissing is a value which comes from a datastore (Edit: in this implementation it is parsed from a XML document) where null is a valid value (because the attribute is not mandatory) and in my business logic null means equals false).

[XmlIgnore]
private bool? createMissing = null;

[XmlAttribute("createMissing")]
public bool CreateMissing
{
    get
    {
        return createMissing.HasValue ? createMissing.Value : false;
    }

    set
    {
        createMissing = value;
    }
}

public bool ShouldSerializeCreateMissing()
{
    return createMissing.HasValue;
}

Nullable<T> has a method called GetValueOrDefault which is the equivalent of your code as false is default(bool). — RobH
– RobH, Commented Feb 15, 2016 at 16:15
This question lacks context. Could you show us where you load the data from the datastore, so that we can better advise you? — 200_success
– 200_success, Commented Feb 15, 2016 at 22:11
I've added the missing context (meta: but was this really worth a downvote?! :D) — seveves
– seveves, Commented Feb 16, 2016 at 6:36

Philip C · Accepted Answer · 2016-02-15 16:08:11Z

5

I don't know about redundant, but this:

return createMissing.HasValue ? createMissing.Value : false;

is equivalent to this:

return createMissing ?? false;

This doesn't look like there's any redundancy to me.

answered Feb 15, 2016 at 16:08

Philip C

7608 silver badges10 bronze badges

\$\begingroup\$ Oh yes thats better. ?? operator is new in C# 6 right? \$\endgroup\$

seveves
– seveves

2016-02-15 16:09:58 +00:00
Commented Feb 15, 2016 at 16:09
1

\$\begingroup\$ @PhilipC - no it's not. The Null Coalescing Operator is ancient. The Null Propagation Operator is the new one. \$\endgroup\$

RobH
– RobH

2016-02-15 18:05:53 +00:00
Commented Feb 15, 2016 at 18:05
\$\begingroup\$ @RobH You're quite right - I was getting it mixed up with the Null Propagation Operator. The Null Coalescing Operator was introduced alongside nullable types in C# 2. I'll get rid of my earlier comment to remove the incorrect information. \$\endgroup\$

Philip C
– Philip C

2016-02-16 07:48:26 +00:00
Commented Feb 16, 2016 at 7:48

Add a comment |

RobH · Accepted Answer · 2016-02-16 08:50:55Z

3

Although Philip C has provided one option, I'd just like to show a couple of others for completeness.

My suggestion from the comments:

public bool CreateMissing
{
    get
    {
        return createMissing.GetValueOrDefault();
    }
    set
    {
        createMissing = value;
    }
}

I personally think this makes the most sense.

Another option would simply be:

return createMissing.HasValue && createMissing.Value;

answered Feb 16, 2016 at 8:50

RobH

17.1k6 gold badges38 silver badges73 bronze badges

Add a comment |

Community · Accepted Answer · 2017-05-23 12:40:59Z

Boolean literals should not be redundant

a redundant statement is something that doesn't add anything. Something like:

if(booleanVariable == true)

or

numericValue + 0

or

numericValue * 1

you get the idea.

In your case, you use the ternary operator:

condition ? value : false;

Notice that condition is evaluated to a boolean value already.

The problem is that the usual solution of simply omitting the redundant stuff doesn't work in your situation. In the above examples, simply remove ==true, + 0 and * 1. In your case there's no such obvious thing to remove.

One could be tempted to simply return the condition part like so:

get
{
    return createMissing;
}

But that doesn't work because bool? cannot be converted to bool implicitly. So what now?

You have to make a decision on what should happen when the value is null. In a way, the ternary operator does this, but (and this is why Sonar tags this as clumsy) in a really clumsy way.

Try something like:

get
{
    return createMissing == true;
}

Wait a second, that's one of the examples of redundant code this answer started with! Wtf?

No, it's not. The difference is subtle, but important: this is not a boolean variable. It's a bool?. It has 3 states, hence checking for equality against true is like checking numericValue == 5, which is perfectly valid.

bool? is like a numeric value of a 2 bit system, except that one of the 4 possible values is not available whatsoever.

Not applicable to your situation, but if you wanted to evaluate both null and true to true, try this code:

get
{
    return createMissing != false;
}

Stack Exchange Network

Nullable boolean value with property

3 Answers 3

You must log in to answer this question.

Hot Network Questions

Nullable boolean value with property

3 Answers 3

You must log in to answer this question.

Related

Hot Network Questions