request: switch all request types to value receivers and value returns

All New*Request()/Make*Request() constructors now return values instead
of pointers. All methods on request types use value receivers and return
values, enabling immutable builder-style chaining.

Removed intermediate spaceRequest, spaceIndexRequest types from the
tarantool package and spaceRequest from the crud package — space and
index fields are inlined directly into each request struct.

Converted all constructors to composite literal style.

Applied the same pattern to arrow/ and settings/ packages.

In the box/ subpackage, request types no longer embed
tarantool.CallRequest. They store it as a private field via
baseCallRequest and implement their own Context() method returning the
wrapper type.

Author: bigbes

CHANGELOG.md

@@ -26,6 +26,12 @@ Versioning](http://semver.org/spec/v2.0.0.html) except to the first release.
 
 ### Changed
 
+* All top-level `New*Request()` constructors now return values instead of
+  pointers. All methods on request types use value receivers and return
+  values, enabling immutable builder-style chaining.
+* Removed intermediate `spaceRequest`, `spaceIndexRequest` types — `space`
+  and `index` fields are now inlined directly into each request struct.
+  The same flattening was applied to `crud.spaceRequest`.
 * Required Go version is `1.24` now (#456).
 * `box.New` returns an error instead of panic (#448).
 * Now cases of `<-ctx.Done()` returns wrapped error provided by `ctx.Cause()`.

MIGRATION.md

@@ -36,6 +36,37 @@ TODO
 * `ConnectionPool.Close()` returns a single error value, combining multiple errors using errors.Join()
 * `Future.Release()` call could be used to free resources allocated for the
   `Future` object created by a `Connection` object.
+* All request types (`PingRequest`, `SelectRequest`, `CallRequest`, etc.) now
+  use value receivers and constructors return values instead of pointers.
+  Builder methods return modified copies instead of mutating in place.
+
+  **Breaking**: calling a builder method without using its return value silently
+  discards the change:
+  ```Go
+  // Before (pointer receivers, mutation in place):
+  req := NewSelectRequest("space")
+  req.Index("idx")           // mutated req directly
+  conn.Do(req)
+
+  // After (value receivers, must use return value):
+  req := NewSelectRequest("space")
+  req = req.Index("idx")     // must reassign
+  conn.Do(req)
+
+  // Or chain directly:
+  conn.Do(NewSelectRequest("space").Index("idx"))
+  ```
+
+  The same value-receiver pattern was applied to `arrow.InsertRequest` and
+  `settings.SetRequest`/`settings.GetRequest`.
+
+  In the `box` subpackage, request types (`InfoRequest`, `UserExistsRequest`,
+  `UserCreateRequest`, `SessionSuRequest`, etc.) no longer embed
+  `tarantool.CallRequest`. They store it as a private field and implement
+  their own `Context()` method returning the wrapper type. Usage stays clean:
+  ```Go
+  req := box.NewUserExistsRequest(username).Context(ctx)
+  ```
 
 ## Migration from v1.x.x to v2.x.x
 

arrow/request.go

@@ -19,25 +19,25 @@ type InsertRequest struct {
 }
 
 // NewInsertRequest returns a new InsertRequest.
-func NewInsertRequest(space interface{}, arrow Arrow) *InsertRequest {
-	return &InsertRequest{
+func NewInsertRequest(space interface{}, arrow Arrow) InsertRequest {
+	return InsertRequest{
 		space: space,
 		arrow: arrow,
 	}
 }
 
 // Type returns a IPROTO_INSERT_ARROW type for the request.
-func (r *InsertRequest) Type() iproto.Type {
+func (r InsertRequest) Type() iproto.Type {
 	return iproto.IPROTO_INSERT_ARROW
 }
 
 // Async returns false to the request return a response.
-func (r *InsertRequest) Async() bool {
+func (r InsertRequest) Async() bool {
 	return false
 }
 
 // Ctx returns a context of the request.
-func (r *InsertRequest) Ctx() context.Context {
+func (r InsertRequest) Ctx() context.Context {
 	return r.ctx
 }
 
@@ -47,20 +47,20 @@ func (r *InsertRequest) Ctx() context.Context {
 // the timeout option for Connection does not affect the lifetime
 // of the request. For those purposes use context.WithTimeout() as
 // the root context.
-func (r *InsertRequest) Context(ctx context.Context) *InsertRequest {
+func (r InsertRequest) Context(ctx context.Context) InsertRequest {
 	r.ctx = ctx
 	return r
 }
 
 // Arrow sets the arrow for insertion the insert arrow request.
 // Note: default value is nil.
-func (r *InsertRequest) Arrow(arrow Arrow) *InsertRequest {
+func (r InsertRequest) Arrow(arrow Arrow) InsertRequest {
 	r.arrow = arrow
 	return r
 }
 
 // Body fills an msgpack.Encoder with the insert arrow request body.
-func (r *InsertRequest) Body(res tarantool.SchemaResolver, enc *msgpack.Encoder) error {
+func (r InsertRequest) Body(res tarantool.SchemaResolver, enc *msgpack.Encoder) error {
 	if err := enc.EncodeMapLen(2); err != nil {
 		return err
 	}
@@ -74,7 +74,7 @@ func (r *InsertRequest) Body(res tarantool.SchemaResolver, enc *msgpack.Encoder)
 }
 
 // Response creates a response for the InsertRequest.
-func (r *InsertRequest) Response(
+func (r InsertRequest) Response(
 	header tarantool.Header,
 	body io.Reader,
 ) (tarantool.Response, error) {

box/info.go

@@ -1,14 +1,15 @@
 package box
 
 import (
+	"context"
 	"fmt"
 
 	"github.com/vmihailenco/msgpack/v5"
 
 	"github.com/tarantool/go-tarantool/v3"
 )
 
-var _ tarantool.Request = (*InfoRequest)(nil)
+var _ tarantool.Request = InfoRequest{}
 
 // Info represents detailed information about the Tarantool instance.
 // It includes version, node ID, read-only status, process ID, cluster information, and more.
@@ -112,14 +113,20 @@ func (ir *InfoResponse) DecodeMsgpack(d *msgpack.Decoder) error {
 // InfoRequest represents a request to retrieve information about the Tarantool instance.
 // It implements the tarantool.Request interface.
 type InfoRequest struct {
-	*tarantool.CallRequest // Underlying Tarantool call request.
+	baseCallRequest
 }
 
 // NewInfoRequest returns a new empty info request.
 func NewInfoRequest() InfoRequest {
-	callReq := tarantool.NewCallRequest("box.info")
-
 	return InfoRequest{
-		callReq,
+		baseCallRequest: baseCallRequest{
+			call: tarantool.NewCallRequest("box.info"),
+		},
 	}
 }
+
+// Context sets a passed context to the request.
+func (req InfoRequest) Context(ctx context.Context) InfoRequest {
+	req.call = req.call.Context(ctx)
+	return req
+}

box/request.go

@@ -0,0 +1,44 @@
+package box
+
+import (
+	"context"
+	"io"
+
+	"github.com/tarantool/go-iproto"
+	"github.com/vmihailenco/msgpack/v5"
+
+	"github.com/tarantool/go-tarantool/v3"
+)
+
+// baseCallRequest wraps a tarantool.CallRequest and implements
+// the tarantool.Request interface by delegation.
+type baseCallRequest struct {
+	call tarantool.CallRequest
+}
+
+// Type returns IPROTO type for the request.
+func (req baseCallRequest) Type() iproto.Type {
+	return req.call.Type()
+}
+
+// Body fills an encoder with the request body.
+func (req baseCallRequest) Body(res tarantool.SchemaResolver,
+	enc *msgpack.Encoder) error {
+	return req.call.Body(res, enc)
+}
+
+// Ctx returns a context of the request.
+func (req baseCallRequest) Ctx() context.Context {
+	return req.call.Ctx()
+}
+
+// Async returns whether the request expects a response.
+func (req baseCallRequest) Async() bool {
+	return req.call.Async()
+}
+
+// Response creates a response for the request.
+func (req baseCallRequest) Response(header tarantool.Header,
+	body io.Reader) (tarantool.Response, error) {
+	return req.call.Response(header, body)
+}