Question: Single statement `if` formatting

[jacobcarpenter]

Looking at System.Threading.Tasks.Dataflow (amazing library by the way), I see three different variations of formatting of single-statement if statements. In one method.

From DataflowBlock.OutputAvailableAsync

One line:

if (source == null) throw new ArgumentNullException("source");

Two lines:

if (cancellationToken.IsCancellationRequested)
    return Common.CreateTaskFromCancellation<bool>(cancellationToken);

With braces:

if (target.Task.IsCompleted)
{
    return target.Task;
}

Are the guidelines for formatting these more nuanced than I'm able to see, or is this just inconsistent formatting? Is this kind of inconsistent formatting normal and acceptable? Is there a preference for how new code should be formatted?

[kiranprabhu]

One here in System.IO.FileInfo
public override String Name
{
get { return _name; } //single line
}

[weshaggard]

We don't have an explicit guideline around this and personally I'm fine with any of them depending on the situation. My general preference would be the "Two lines" version for most cases unless you are nesting in lots of scopes then I would use the "With braces" version to ensure things don't accidentally go in an unintended scope.

[jacobcarpenter]

Thanks! That sounds great.

I'm happy to have this issue closed, unless you want further discussion about extending the C# Coding Style with some guidance for this situation.

[mellinoe]

I would imagine the difference between the first vs. the second (one-line vs. two-line) is just the length of the line; we probably didn't want to have such a long single line for the second example, for readability, etc.

Also, in general (although there are still exceptions...) you may see that parameter validation checks are generally on one or two lines without braces, and parts of the main body logic are more likely to have braces. These aren't really "rules", and they definitely aren't written down anywhere.

[paulomorgado]

There are a few horror stories about using the two lines style. Ask Apple.

[terrajobst]

My gut feel tells me that we should settle on a specific convention.

/cc @jaredpar and @Priya91

[jaredpar]

I think we should go with the two line version.

The goal of the style guidelines is to have consistency within the code base. As others have pointed out the single line version isn't always realistic because of line length. Given that I'd go with the two line version.

[sharwell]

I use the following rule:

• Never use the single-line form
• Without braces
  • Only allowed if the body of every block associated with an if/else if/.../else compound statement is placed on a single line.
• With braces
  • Always acceptable
  • If any block of an if/else if/.../else compound statement uses braces, then all blocks in the compound statement use braces
  • If a single statement body spans multiple lines (e.g. if it is split to keep a line from being too long), then braces must be used

[terrajobst]

My personal preference is identical to what @sharwell wrote.

[jaredpar]

I think that is a very sensible set of rules.

On Saturday, January 10, 2015, Immo Landwerth notifications@github.com
wrote:

My personal preference is identical to what @sharwell
https://github.com/sharwell wrote.

—
Reply to this email directly or view it on GitHub
https://github.com/dotnet/corefx/issues/381#issuecomment-69475130.

Jared Parsons
http://blog.paranoidcoding.com/
http://twitter.com/jaredpar

[weshaggard]

I agree. I tried to summarize it in our code guideline wiki as:

A single line statement block can go without braces but the block must be properly indented on its own line and it must not be nested in other statement blocks that use braces (See issue 381 for examples).

Please let me know if you think the guidance needs further clarification.

Thanks @jacobcarpenter for posing the question and @sharwell for suggesting the guidance, I'm closing this issue now.

[paulomorgado]

Apart the use of goto, for me, one of the causes of Apple's goto fail bug was allowing two line ifs without the braces.

In the extremely rare occasions I use unbraced "blocks" is if they are if the whole statement (or statement segment) is on the same line.

[robinsedlaczek]

I know this issue was closed long time ago, but if you allow, I like to add a thought: we also discussed this topic with our teams when we created our internal guidelines long time ago. And we came to the point, that we always want to use braces. Also for single line statement blocks. So we must not think about and incorrect scoping can not occur accidentally.

[davidsh]

cc: @CIPop

+1. I agree that all if statements should use braces even for single line statements.