code sexiness question

[Richard Deeming]

If you're using VS2019 or 2022, you can still use that construct in .NET 4.7.2; you just need to manually edit your project file to enable C# 9. :) If you already have a <LangVersion> element in the file, change it to <LangVersion>9.0</LangVersion>. Otherwise, add that element next to the <TargetFramework> element. Quite a few C# 8/9/10 features will work in .NET Framework projects: Using C# 9 outside .NET 5 · Discussion #47701 · dotnet/roslyn · GitHub[^]

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"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

[Richard Deeming]

switch expression - C# reference | Microsoft Docs[^] Pattern matching overview - C# guide | Microsoft Docs[^] :)

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"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

[OriginalGriff]

I'd use the first version - that way if SelectedObject is changed (by another thread for example) the non-null value is preserved and the app doesn't crash. It's the way I handle event raising - my standard template code is:

    /// /// Event to indicate Description
    /// 
    public event EventHandler Name;
    /// /// Called to signal to subscribers that Description
    /// 
    /// 
    protected virtual void OnName(EventArgs e)
        {
        EventHandler eh = Name;
        if (eh != null)
            {
            eh(this, e);
            }
        }

That way, in the (unlikely) event that the last handler is removed from the c=hain, the app doesn't crash and does something sensible.

"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt AntiTwitter: @DalekDave is now a follower!

[Super Lloyd]

Interesting... Though in our case there is some sort of build system, which is still mysterious to me, that generate the .csproj files.. so I would need to get familiar with that first! :laugh: In fact... I really ought to become more familiar with this particular system.... :sigh:

A new .NET Serializer All in one Menu-Ribbon Bar Taking over the world since 1371!

[Richard Deeming]

Two obvious alternatives to that:

public event EventHandler Name = delegate { };

protected virtual void OnName(EventArgs e)
{
Name(this, e); // Name can never be null
}

public event EventHandler Name;

protected virtual void OnName(EventArgs e)
{
Name?.Invoke(this, e);
}

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"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

[honey the codewitch]

Understandable. I can't stand code reviews myself, because I have some different philosophies about how code needs to be written than a lot of people I have worked with. However, when I am in a position where I am in charge of code reviews, I tend to go easy and stick to enforcing in-shop style guidelines more than anything. I don't care about fast for bizdev unless something is slow enough you want to get out and push. I would have accepted either version of your code. I think both are readable *enough* - and this is one of the areas where I differ with a lot of people. I don't spend as much time chasing readability as other coders. I like to look at cognitive load more than readability, because I feel like readability can be had by reading the complicated parts of a function more than once. The trick is in *understanding* what you've read. That's the part where I care, but also the part I'm not great at. One of the reasons I write here is to try to improve my skillset in terms of making my code understandable. My functions are too long, but that's due to some cognitive issues I have myself, and it's part of how I've adapted to them.

Real programmers use butterflies

[OriginalGriff]

The first relies on the empty delegate: if someone else sees the code and removes it as it clearly does nothing then you are back to a potential failure. Unlikely, yes - but I don't like app failures. :D The second is .NET version dependant: the null conditional operator was introduced at C# 6, and some of my code predates that.

"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt AntiTwitter: @DalekDave is now a follower!

[11917640 Member]

Very good good code review result. Absolutely meaningless and harmless change. You and code reviewer, and of course, managers, are happy. BTW, after native optimizations both versions may be absolutely identical. But don't tell about this to your manager.

[snorkie]

Are we coding in C# or Perl? I always felt like C# was a nice balance between COBOL and Perl. But the recent changes have it trending towards Perl. I hear the excuse "it saves typing" as if we aren't on a message board or slack typing all day long.

Hogan

[Lost User]

I have problems with both. "var" is a coding shortcut when you're too lazy to type, and should be replaced with the actual type when it resolves (before release); so the next guy doesn't have to "intelli-sense" it. "Object" seems more appropriate in this case. I dislike "long" if's and would have "if not null return x" instead of (if null etc.) Even though it works, I don't declare properties "after" the method that references them. The return "assign" is "different". Then there are the if's with bracketed blocks and some without. Saving keystrokes? etc.

It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it. ― Confucian Analects: Rules of Confucius about his food

[Gary R Wheeler]

I would have done things this way:

private IMultipleComponentHandler SelectionHandler
{
get
{
if (m_selectionHandler == null)
{
if (SelectedObject is IMultipleComponentHandler handler)
{
m_selectionHandler = handler;
}

        else
        {
            object\[\] collection;
            
            if (SelectedObject is IEnumerable e
                && !SelectedObject.GetAttributes().Any())
            {
                collection = e as object\[\] ?? e.Cast().ToArray();
            }
            else if (SelectedObject != null)
            {
                collection = new\[\] { SelectedObject };
            }
            else
            {
                collection = Array.Empty();
            }

            m\_selectionHandler = new InspectorMultipleComponentHandler(collection);
        }
    }
    
    return m\_selectionHandler;
}

}
private IMultipleComponentHandler m_selectionHandler;I'm an old fart who prefers single-exit :-D .

Software Zen: delete this;

[Fueled By Decaff]

I would be tempted to extract the contents of the if statement as a function, like this:

    public IMultipleComponentHandler SelectionHandler
    {
        get
        {
            if (m\_selectionHandler == null)
            {
                m\_selectionHandler = InitialiseSelectionHandler(SelectedObject);
            }
            return m\_selectionHandler;
        }
    }

    private IMultipleComponentHandler InitialiseSelectionHandler(object selectedObject)
    {
        if (selectedObject is IMultipleComponentHandler handler)
            return m\_selectionHandler = handler;

        object\[\] collection;
        if (selectedObject is IEnumerable e
            && !selectedObject.GetAttributes().Any())
        {
            collection = e as object\[\] ?? e.Cast().ToArray();
        }
        else if (selectedObject != null)
        {
            collection = new\[\] { selectedObject };
        }
        else
        {
            collection = Array.Empty();
        }
        return new InspectorMultipleComponentHandler(collection);
    }

    private IMultipleComponentHandler m\_selectionHandler;

This hides the issue of using a temporary variable, snapshots the SelectedObject so the value being used can not change while updating the handler and the getter property for SelectionHandler becomes easier to read.

An added bonus is if SelectedObject changes you can update the handler by calling InitialiseSelectionHandler.

[Daniele Rota Nodari]

This is way cleaner.. It is a sort of lazy initialization.. and usually it is split exactly that way: a backing field, a property that lazily initializes the field, and a method that performs the initialization. This also highlight a possible race condition after the very first null check, that can be avoided by a double-checked locking inside the property get accessor; and the InitialiseSelectionHandler method would remain untouched. I'd just keep the backing field close to the property (I usually keep the field immediately before the property).

[Andre_Prellwitz]

It’s unlikely the compiler knows that no other thread may change the SelectedObject during the getter body. One should acknowledge that fact by capturing its value, not for speed or readability, but for correctness. That so many people find it trivial or overly optimizing is really scary. Pragmatically it may be a non-issue, but it’s a time-bomb and there’s arguably no justification for the “simpler” syntax. Concurrency is hard.

[Andre_Prellwitz]

You’re not wrong, but you’re also not necessarily right. Coding preferences should be agreed upon, codified, and automated to avoid debate. The important thing is that there’s consistency. Calling a coding practice “lazy” (like the use of ‘var’) is condescending, at best, and smells of arrogance. It’s also associated with narrow-mindedness, and quite frankly, can date you in a bad way. I’m sure the intent was a call for action, but your reasoning and diction could be improved. Very simply, the guidance on the use of ‘var’ states that it should be used only if the type is repeated or obvious (without IntelliSense) on the right side of the equals sign; this simultaneously makes it easier to spot variable declarations while respecting the intelligence of the reader, who may not really care what the type is up front, especially if the name is well-chosen or the type name is long. A similar logic can be applied, per your preference, for the implicit new() operator, though I tend to see those used mostly on field initializers. Having said that, the Framework Design Guidelines recommends *against* the use of var, except when using ‘new’, ‘as’, or a hard cast, in which cases it is *permissible*.

[englebart]

Careful with the double checked locking… I suspect C# might fall under the Java or C++ umbrella. [The "Double-Checked Locking is Broken" Declaration](https://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html)