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Enhance documentation for @typeChangedFrom and @returnTypeChangedFrom decorators #9563

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50 changes: 40 additions & 10 deletions packages/versioning/README.md
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Expand Up @@ -214,7 +214,12 @@ op newName(): void;

#### `@returnTypeChangedFrom`

Identifies when the target type changed.
Declares that the return type of an operation has changed starting at a given version,
while keeping earlier versions consistent with the previous return type.

This decorator is used to track return type changes across API versions. When applied,
the operation will return `oldType` in versions before the specified `version`,
and the current return type definition in the specified version and later.

```typespec
@TypeSpec.Versioning.returnTypeChangedFrom(version: EnumMember, oldType: unknown)
Expand All @@ -226,14 +231,28 @@ Identifies when the target type changed.

##### Parameters

| Name | Type | Description |
| ------- | ------------ | -------------------------------------------- |
| version | `EnumMember` | The version that the target type changed in. |
| oldType | `unknown` | The previous type of the target. |
| Name | Type | Description |
| ------- | ------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| version | `EnumMember` | The version when the return type change takes effect. The new return type applies<br />from this version onwards, while the old return type applies to earlier versions. |
| oldType | `unknown` | The previous return type used before the specified version. |

##### Examples

```tsp
// In v1: returns a string
// In v2+: returns an int32
@returnTypeChangedFrom(Versions.v2, string)
op getUserId(): int32;
```

#### `@typeChangedFrom`

Identifies when the target type changed.
Declares that the type of a model property has changed starting at a given version,
while keeping earlier versions consistent with the previous type.

This decorator is used to track type changes across API versions. When applied,
the property will use `oldType` in versions before the specified `version`,
and the current type definition in the specified version and later.

```typespec
@TypeSpec.Versioning.typeChangedFrom(version: EnumMember, oldType: unknown)
Expand All @@ -245,10 +264,21 @@ Identifies when the target type changed.

##### Parameters

| Name | Type | Description |
| ------- | ------------ | -------------------------------------------- |
| version | `EnumMember` | The version that the target type changed in. |
| oldType | `unknown` | The previous type of the target. |
| Name | Type | Description |
| ------- | ------------ | --------------------------------------------------------------------------------------------------------------------------------------------------- |
| version | `EnumMember` | The version when the type change takes effect. The new type applies<br />from this version onwards, while the old type applies to earlier versions. |
| oldType | `unknown` | The previous type used before the specified version. |

##### Examples

```tsp
model Foo {
// In v1: id is a string
// In v2+: id is an int32
@typeChangedFrom(Versions.v2, string)
id: int32;
}
```

#### `@useDependency`

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40 changes: 34 additions & 6 deletions packages/versioning/generated-defs/TypeSpec.Versioning.ts
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Expand Up @@ -202,10 +202,25 @@ export type MadeRequiredDecorator = (
) => DecoratorValidatorCallbacks | void;

/**
* Identifies when the target type changed.
* Declares that the type of a model property has changed starting at a given version,
* while keeping earlier versions consistent with the previous type.
*
* @param version The version that the target type changed in.
* @param oldType The previous type of the target.
* This decorator is used to track type changes across API versions. When applied,
* the property will use `oldType` in versions before the specified `version`,
* and the current type definition in the specified version and later.
*
* @param version The version when the type change takes effect. The new type applies
* from this version onwards, while the old type applies to earlier versions.
* @param oldType The previous type used before the specified version.
* @example
* ```tsp
* model Foo {
* // In v1: id is a string
* // In v2+: id is an int32
* @typeChangedFrom(Versions.v2, string)
* id: int32;
* }
* ```
*/
export type TypeChangedFromDecorator = (
context: DecoratorContext,
Expand All @@ -215,10 +230,23 @@ export type TypeChangedFromDecorator = (
) => DecoratorValidatorCallbacks | void;

/**
* Identifies when the target type changed.
* Declares that the return type of an operation has changed starting at a given version,
* while keeping earlier versions consistent with the previous return type.
*
* This decorator is used to track return type changes across API versions. When applied,
* the operation will return `oldType` in versions before the specified `version`,
* and the current return type definition in the specified version and later.
*
* @param version The version that the target type changed in.
* @param oldType The previous type of the target.
* @param version The version when the return type change takes effect. The new return type applies
* from this version onwards, while the old return type applies to earlier versions.
* @param oldType The previous return type used before the specified version.
* @example
* ```tsp
* // In v1: returns a string
* // In v2+: returns an int32
* @returnTypeChangedFrom(Versions.v2, string)
* op getUserId(): int32;
* ```
*/
export type ReturnTypeChangedFromDecorator = (
context: DecoratorContext,
Expand Down
46 changes: 40 additions & 6 deletions packages/versioning/lib/decorators.tsp
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Expand Up @@ -178,15 +178,49 @@ extern dec madeOptional(target: ModelProperty, version: EnumMember);
extern dec madeRequired(target: ModelProperty, version: EnumMember);

/**
* Identifies when the target type changed.
* @param version The version that the target type changed in.
* @param oldType The previous type of the target.
* Declares that the type of a model property has changed starting at a given version,
* while keeping earlier versions consistent with the previous type.
*
* This decorator is used to track type changes across API versions. When applied,
* the property will use `oldType` in versions before the specified `version`,
* and the current type definition in the specified version and later.
*
* @param version The version when the type change takes effect. The new type applies
* from this version onwards, while the old type applies to earlier versions.
* @param oldType The previous type used before the specified version.
*
* @example
*
* ```tsp
* model Foo {
* // In v1: id is a string
* // In v2+: id is an int32
* @typeChangedFrom(Versions.v2, string)
* id: int32;
* }
* ```
*/
extern dec typeChangedFrom(target: ModelProperty, version: EnumMember, oldType: unknown);

/**
* Identifies when the target type changed.
* @param version The version that the target type changed in.
* @param oldType The previous type of the target.
* Declares that the return type of an operation has changed starting at a given version,
* while keeping earlier versions consistent with the previous return type.
*
* This decorator is used to track return type changes across API versions. When applied,
* the operation will return `oldType` in versions before the specified `version`,
* and the current return type definition in the specified version and later.
*
* @param version The version when the return type change takes effect. The new return type applies
* from this version onwards, while the old return type applies to earlier versions.
* @param oldType The previous return type used before the specified version.
*
* @example
*
* ```tsp
* // In v1: returns a string
* // In v2+: returns an int32
* @returnTypeChangedFrom(Versions.v2, string)
* op getUserId(): int32;
* ```
*/
extern dec returnTypeChangedFrom(target: Operation, version: EnumMember, oldType: unknown);
50 changes: 40 additions & 10 deletions website/src/content/docs/docs/libraries/versioning/reference/decorators.md
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Expand Up @@ -164,7 +164,12 @@ op newName(): void;

### `@returnTypeChangedFrom` {#@TypeSpec.Versioning.returnTypeChangedFrom}

Identifies when the target type changed.
Declares that the return type of an operation has changed starting at a given version,
while keeping earlier versions consistent with the previous return type.

This decorator is used to track return type changes across API versions. When applied,
the operation will return `oldType` in versions before the specified `version`,
and the current return type definition in the specified version and later.

```typespec
@TypeSpec.Versioning.returnTypeChangedFrom(version: EnumMember, oldType: unknown)
Expand All @@ -176,14 +181,28 @@ Identifies when the target type changed.

#### Parameters

| Name | Type | Description |
| ------- | ------------ | -------------------------------------------- |
| version | `EnumMember` | The version that the target type changed in. |
| oldType | `unknown` | The previous type of the target. |
| Name | Type | Description |
| ------- | ------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| version | `EnumMember` | The version when the return type change takes effect. The new return type applies<br />from this version onwards, while the old return type applies to earlier versions. |
| oldType | `unknown` | The previous return type used before the specified version. |

#### Examples

```tsp
// In v1: returns a string
// In v2+: returns an int32
@returnTypeChangedFrom(Versions.v2, string)
op getUserId(): int32;
```

### `@typeChangedFrom` {#@TypeSpec.Versioning.typeChangedFrom}

Identifies when the target type changed.
Declares that the type of a model property has changed starting at a given version,
while keeping earlier versions consistent with the previous type.

This decorator is used to track type changes across API versions. When applied,
the property will use `oldType` in versions before the specified `version`,
and the current type definition in the specified version and later.

```typespec
@TypeSpec.Versioning.typeChangedFrom(version: EnumMember, oldType: unknown)
Expand All @@ -195,10 +214,21 @@ Identifies when the target type changed.

#### Parameters

| Name | Type | Description |
| ------- | ------------ | -------------------------------------------- |
| version | `EnumMember` | The version that the target type changed in. |
| oldType | `unknown` | The previous type of the target. |
| Name | Type | Description |
| ------- | ------------ | --------------------------------------------------------------------------------------------------------------------------------------------------- |
| version | `EnumMember` | The version when the type change takes effect. The new type applies<br />from this version onwards, while the old type applies to earlier versions. |
| oldType | `unknown` | The previous type used before the specified version. |

#### Examples

```tsp
model Foo {
// In v1: id is a string
// In v2+: id is an int32
@typeChangedFrom(Versions.v2, string)
id: int32;
}
```

### `@useDependency` {#@TypeSpec.Versioning.useDependency}

Expand Down