Tutorial: Write a custom string interpolation handler – couple of small mistakes

[deep-outcome]

# 1

[InterpolatedStringHandler]
public ref struct LogInterpolatedStringHandler
{
    …
    // Add the receiver argument:
    …

I guess // Add the receiver argument: is forgotten since Improved Interpolated Strings discusses declaratively receiver term.

# 2

public LogInterpolatedStringHandler(int literalLength, int formattedCount, LogLevel level, Logger logger, out bool isEnabled)
{
    enabled = logger.EnabledLevel >= level;
    Console.WriteLine($"\tliteral length: {literalLength}, formattedCount: {formattedCount}");
    if (enabled)
    {
        builder = new StringBuilder(literalLength);
    }
    isEnabled = enabled;
}

In fact there are 2 failures:

• logger and level parameters are switched so declaration [InterpolatedStringHandlerArgument("", "level")] LogInterpolatedStringHandler builder does not work with it.
• LogInterpolatedStringHandler is declared as struct so builder must be definitely assigned when .ctor returns. So either it must be changed to class or used something like builder = enabled ? new () : null;.

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Document Details

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• ID: 99599c47-14ba-6e35-9b63-daa928f764bb
• Version Independent ID: e80a06d-bfbc-29f1-1cca-248460e523d3
• Content: Explore string interpolation handlers
• Content Source: docs/csharp/whats-new/tutorials/interpolated-string-handler.md
• Product: dotnet-csharp
• Technology: csharp-whats-new
• GitHub Login: @BillWagner
• Microsoft Alias: wiwagn

[BillWagner]

I'll leave this open to inviestigate.

For #1, that's a stray comment in the initial sample and should be removed.

For #2, the code compiles in the samples repo, so I'll have to look at where the text disagrees with the sample code.

[deep-outcome]

For #2, the code compiles in the samples repo, so I'll have to look at where the text disagrees with the sample code.

Yes, it gets compiled since call site in snippets specified correctly [InterpolatedStringHandlerArgument("level", "")] LogInterpolatedStringHandler builder) but this implementation is not used on page.