Consolidated the C# nullable value types articles #15676
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pkulikov
requested review from
BillWagner,
KathleenDollard,
stevestein and
Thraka
as code owners
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This is great work @pkulikov
I had one question and a couple suggestions. Let me know your thoughts.
| @@ -22,7 +22,7 @@ Available in C# 8.0 and later, the null-coalescing assignment operator `??=` ass | |||
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| The left-hand operand of the `??=` operator must be a variable, a [property](../../programming-guide/classes-and-structs/properties.md), or an [indexer](../../programming-guide/indexers/index.md) element. | |||
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| In C# 7.3 and earlier, the type of the left-hand operand of the `??` operator must be either a reference type or a [nullable value type](../../programming-guide/nullable-types/index.md). Beginning with C# 8.0, that requirement is replaced with the following: the type of the left-hand operand of the `??` and `??=` operators cannot be a non-nullable value type. In particular, beginning with C# 8.0, you can use the null-coalescing operators with unconstrained type parameters: | |||
| In C# 7.3 and earlier, the type of the left-hand operand of the `??` operator must be either a [reference type](../keywords/reference-types.md) or a [nullable value type](../builtin-types/nullable-value-types.md). Beginning with C# 8.0, that requirement is replaced with the following: the type of the left-hand operand of the `??` and `??=` operators cannot be a non-nullable value type. In particular, beginning with C# 8.0, you can use the null-coalescing operators with unconstrained type parameters: | |||
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nit: I'd add the quotes to make it clear where the text from the spec ends:
| In C# 7.3 and earlier, the type of the left-hand operand of the `??` operator must be either a [reference type](../keywords/reference-types.md) or a [nullable value type](../builtin-types/nullable-value-types.md). Beginning with C# 8.0, that requirement is replaced with the following: the type of the left-hand operand of the `??` and `??=` operators cannot be a non-nullable value type. In particular, beginning with C# 8.0, you can use the null-coalescing operators with unconstrained type parameters: | |
| In C# 7.3 and earlier, the type of the left-hand operand of the `??` operator must be either a [reference type](../keywords/reference-types.md) or a [nullable value type](../builtin-types/nullable-value-types.md). Beginning with C# 8.0, that requirement is replaced with the following: "the type of the left-hand operand of the `??` and `??=` operators cannot be a non-nullable value type." In particular, beginning with C# 8.0, you can use the null-coalescing operators with unconstrained type parameters: |
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@BillWagner would it be fine to quote not direct spec text? The updated spec text (check the end of the linked section) reads:
If A exists and is a non-nullable value type, a compile-time error occurs.
where A - is the type of the left-hand operand.
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| [!code-csharp-interactive[?? operator](~/samples/csharp/language-reference/builtin-types/NullableValueTypes.cs#NullCoalescing)] | ||
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| Use the <xref:System.Nullable%601.GetValueOrDefault?displayProperty=nameWithType> method if the value to be used when a value of a nullable value type is `null` should be the [default](../keywords/default-values-table.md) value of the underlying value type. |
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This sentence read very awkward for me. How about this version:
| Use the <xref:System.Nullable%601.GetValueOrDefault?displayProperty=nameWithType> method if the value to be used when a value of a nullable value type is `null` should be the [default](../keywords/default-values-table.md) value of the underlying value type. | |
| Often, you want to use the [default](../keywords/default-values-table.md) value of the underlying value type in place | |
| of the `null` of a nullable value type. The <xref:System.Nullable%601.GetValueOrDefault?displayProperty=nameWithType> method accomplishes this. |
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@BillWagner I like your wording more, thanks. I've edited it a bit and also tried to apply it to the paragraph above.
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| [!code-csharp-interactive[boxing and unboxing](~/samples/csharp/language-reference/builtin-types/NullableValueTypes.cs#Boxing)] | ||
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| ## How to identify a nullable value type |
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Should this section include an "Important" note that these operations do not apply for nullable reference types. ( know that you've been very careful to include "value" in "nullable value type" throughout the article. That makes me think it would be redundant. On the other hand, the syntax would seem to imply that there are similarities between int? and string?. That's a bad assumption.
What are your thoughts?
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@BillWagner I've added the note to the end of the section. Though being redundant, I think it doesn't hurt.
Also, after this article is published, should the issue #9662 be "redirected" to the new article?
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@BillWagner I've addressed your feedback with one item waiting for your response. |
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This looks great @pkulikov I'll |
now.
Fixes #14726
Supported by dotnet/samples#1694
Contributes to #13421