reflect

package
v0.9.9 Latest Latest
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 Go to latest Published: Dec 31, 2024 License: Apache-2.0 Imports: 10 Imported by: 0

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Constants

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const Ptr = Pointer

Ptr is the old name for the Pointer kind.

Variables

This section is empty.

Functions

This section is empty.

Types

type ChanDir 

type ChanDir int

ChanDir represents a channel type's direction. 

const (
	RecvDir ChanDir             = 1 << iota // <-chan
	SendDir                                 // chan<-
	BothDir = RecvDir | SendDir             // chan
)

type Kind 

type Kind uint

A Kind represents the specific kind of type that a Type represents. The zero Kind is not a valid kind. 

const (
	Invalid Kind = iota
	Bool
	Int
	Int8
	Int16
	Int32
	Int64
	Uint
	Uint8
	Uint16
	Uint32
	Uint64
	Uintptr
	Float32
	Float64
	Complex64
	Complex128
	Array
	Chan
	Func
	Interface
	Map
	Pointer
	Slice
	String
	Struct
	UnsafePointer
)

func (Kind) String 

func (k Kind) String() string

String returns the name of k.

type MapIter added in v0.9.8 

type MapIter struct {
	// contains filtered or unexported fields
}

A MapIter is an iterator for ranging over a map. See Value.MapRange.

func (*MapIter) Key added in v0.9.8 

func (iter *MapIter) Key() Value

Key returns the key of iter's current map entry.

func (*MapIter) Next added in v0.9.8 

func (iter *MapIter) Next() bool

Next advances the map iterator and reports whether there is another entry. It returns false when iter is exhausted; subsequent calls to Key, Value, or Next will panic.

func (*MapIter) Reset added in v0.9.8 

func (iter *MapIter) Reset(v Value)

Reset modifies iter to iterate over v. It panics if v's Kind is not Map and v is not the zero Value. Reset(Value{}) causes iter to not to refer to any map, which may allow the previously iterated-over map to be garbage collected.

func (*MapIter) Value added in v0.9.8 

func (iter *MapIter) Value() Value

Value returns the value of iter's current map entry.

type Method 

type Method struct {
	// Name is the method name.
	Name string

	// PkgPath is the package path that qualifies a lower case (unexported)
	// method name. It is empty for upper case (exported) method names.
	// The combination of PkgPath and Name uniquely identifies a method
	// in a method set.
	// See https://golang.org/ref/spec#Uniqueness_of_identifiers
	PkgPath string

	Type  Type  // method type
	Func  Value // func with receiver as first argument
	Index int   // index for Type.Method
}

Method represents a single method.

func (Method) IsExported 

func (m Method) IsExported() bool

IsExported reports whether the method is exported.

type StructField 

type StructField struct {
	// Name is the field name.
	Name string

	// PkgPath is the package path that qualifies a lower case (unexported)
	// field name. It is empty for upper case (exported) field names.
	// See https://golang.org/ref/spec#Uniqueness_of_identifiers
	PkgPath string

	Type      Type      // field type
	Tag       StructTag // field tag string
	Offset    uintptr   // offset within struct, in bytes
	Index     []int     // index sequence for Type.FieldByIndex
	Anonymous bool      // is an embedded field
}

A StructField describes a single field in a struct.

func (StructField) IsExported 

func (f StructField) IsExported() bool

IsExported reports whether the field is exported.

type StructTag 

type StructTag string

A StructTag is the tag string in a struct field.

By convention, tag strings are a concatenation of optionally space-separated key:"value" pairs. Each key is a non-empty string consisting of non-control characters other than space (U+0020 ' '), quote (U+0022 '"'), and colon (U+003A ':'). Each value is quoted using U+0022 '"' characters and Go string literal syntax.

func (StructTag) Get 

func (tag StructTag) Get(key string) string

Get returns the value associated with key in the tag string. If there is no such key in the tag, Get returns the empty string. If the tag does not have the conventional format, the value returned by Get is unspecified. To determine whether a tag is explicitly set to the empty string, use Lookup.

func (StructTag) Lookup 

func (tag StructTag) Lookup(key string) (value string, ok bool)

Lookup returns the value associated with key in the tag string. If the key is present in the tag the value (which may be empty) is returned. Otherwise the returned value will be the empty string. The ok return value reports whether the value was explicitly set in the tag string. If the tag does not have the conventional format, the value returned by Lookup is unspecified.

type Type 

type Type interface {

	// Align returns the alignment in bytes of a value of
	// this type when allocated in memory.
	Align() int

	// FieldAlign returns the alignment in bytes of a value of
	// this type when used as a field in a struct.
	FieldAlign() int

	// Method returns the i'th method in the type's method set.
	// It panics if i is not in the range [0, NumMethod()).
	//
	// For a non-interface type T or *T, the returned Method's Type and Func
	// fields describe a function whose first argument is the receiver,
	// and only exported methods are accessible.
	//
	// For an interface type, the returned Method's Type field gives the
	// method signature, without a receiver, and the Func field is nil.
	//
	// Methods are sorted in lexicographic order.
	Method(int) Method

	// MethodByName returns the method with that name in the type's
	// method set and a boolean indicating if the method was found.
	//
	// For a non-interface type T or *T, the returned Method's Type and Func
	// fields describe a function whose first argument is the receiver.
	//
	// For an interface type, the returned Method's Type field gives the
	// method signature, without a receiver, and the Func field is nil.
	MethodByName(string) (Method, bool)

	// NumMethod returns the number of methods accessible using Method.
	//
	// For a non-interface type, it returns the number of exported methods.
	//
	// For an interface type, it returns the number of exported and unexported methods.
	NumMethod() int

	// Name returns the type's name within its package for a defined type.
	// For other (non-defined) types it returns the empty string.
	Name() string

	// PkgPath returns a defined type's package path, that is, the import path
	// that uniquely identifies the package, such as "encoding/base64".
	// If the type was predeclared (string, error) or not defined (*T, struct{},
	// []int, or A where A is an alias for a non-defined type), the package path
	// will be the empty string.
	PkgPath() string

	// Size returns the number of bytes needed to store
	// a value of the given type; it is analogous to unsafe.Sizeof.
	Size() uintptr

	// String returns a string representation of the type.
	// The string representation may use shortened package names
	// (e.g., base64 instead of "encoding/base64") and is not
	// guaranteed to be unique among types. To test for type identity,
	// compare the Types directly.
	String() string

	// Kind returns the specific kind of this type.
	Kind() Kind

	// Implements reports whether the type implements the interface type u.
	Implements(u Type) bool

	// AssignableTo reports whether a value of the type is assignable to type u.
	AssignableTo(u Type) bool

	// ConvertibleTo reports whether a value of the type is convertible to type u.
	// Even if ConvertibleTo returns true, the conversion may still panic.
	// For example, a slice of type []T is convertible to *[N]T,
	// but the conversion will panic if its length is less than N.
	ConvertibleTo(u Type) bool

	// Comparable reports whether values of this type are comparable.
	// Even if Comparable returns true, the comparison may still panic.
	// For example, values of interface type are comparable,
	// but the comparison will panic if their dynamic type is not comparable.
	Comparable() bool

	// Bits returns the size of the type in bits.
	// It panics if the type's Kind is not one of the
	// sized or unsized Int, Uint, Float, or Complex kinds.
	Bits() int

	// ChanDir returns a channel type's direction.
	// It panics if the type's Kind is not Chan.
	ChanDir() ChanDir

	// IsVariadic reports whether a function type's final input parameter
	// is a "..." parameter. If so, t.In(t.NumIn() - 1) returns the parameter's
	// implicit actual type []T.
	//
	// For concreteness, if t represents func(x int, y ... float64), then
	//
	//	t.NumIn() == 2
	//	t.In(0) is the reflect.Type for "int"
	//	t.In(1) is the reflect.Type for "[]float64"
	//	t.IsVariadic() == true
	//
	// IsVariadic panics if the type's Kind is not Func.
	IsVariadic() bool

	// Elem returns a type's element type.
	// It panics if the type's Kind is not Array, Chan, Map, Pointer, or Slice.
	Elem() Type

	// Field returns a struct type's i'th field.
	// It panics if the type's Kind is not Struct.
	// It panics if i is not in the range [0, NumField()).
	Field(i int) StructField

	// FieldByIndex returns the nested field corresponding
	// to the index sequence. It is equivalent to calling Field
	// successively for each index i.
	// It panics if the type's Kind is not Struct.
	FieldByIndex(index []int) StructField

	// FieldByName returns the struct field with the given name
	// and a boolean indicating if the field was found.
	FieldByName(name string) (StructField, bool)

	// FieldByNameFunc returns the struct field with a name
	// that satisfies the match function and a boolean indicating if
	// the field was found.
	//
	// FieldByNameFunc considers the fields in the struct itself
	// and then the fields in any embedded structs, in breadth first order,
	// stopping at the shallowest nesting depth containing one or more
	// fields satisfying the match function. If multiple fields at that depth
	// satisfy the match function, they cancel each other
	// and FieldByNameFunc returns no match.
	// This behavior mirrors Go's handling of name lookup in
	// structs containing embedded fields.
	FieldByNameFunc(match func(string) bool) (StructField, bool)

	// In returns the type of a function type's i'th input parameter.
	// It panics if the type's Kind is not Func.
	// It panics if i is not in the range [0, NumIn()).
	In(i int) Type

	// Key returns a map type's key type.
	// It panics if the type's Kind is not Map.
	Key() Type

	// Len returns an array type's length.
	// It panics if the type's Kind is not Array.
	Len() int

	// NumField returns a struct type's field count.
	// It panics if the type's Kind is not Struct.
	NumField() int

	// NumIn returns a function type's input parameter count.
	// It panics if the type's Kind is not Func.
	NumIn() int

	// NumOut returns a function type's output parameter count.
	// It panics if the type's Kind is not Func.
	NumOut() int

	// Out returns the type of a function type's i'th output parameter.
	// It panics if the type's Kind is not Func.
	// It panics if i is not in the range [0, NumOut()).
	Out(i int) Type
	// contains filtered or unexported methods
}

Type is the representation of a Go type.

Not all methods apply to all kinds of types. Restrictions, if any, are noted in the documentation for each method. Use the Kind method to find out the kind of type before calling kind-specific methods. Calling a method inappropriate to the kind of type causes a run-time panic.

Type values are comparable, such as with the == operator, so they can be used as map keys. Two Type values are equal if they represent identical types.

func FuncOf added in v0.9.8 

func FuncOf(in, out []Type, variadic bool) Type

FuncOf returns the function type with the given argument and result types. For example if k represents int and e represents string, FuncOf([]Type{k}, []Type{e}, false) represents func(int) string.

The variadic argument controls whether the function is variadic. FuncOf panics if the in[len(in)-1] does not represent a slice and variadic is true.

func MapOf added in v0.9.8 

func MapOf(key, elem Type) Type

MapOf returns the map type with the given key and element types. For example, if k represents int and e represents string, MapOf(k, e) represents map[int]string.

If the key type is not a valid map key type (that is, if it does not implement Go's == operator), MapOf panics.

func PointerTo 

func PointerTo(t Type) Type

PointerTo returns the pointer type with element t. For example, if t represents type Foo, PointerTo(t) represents *Foo.

func PtrTo 

func PtrTo(t Type) Type

PtrTo returns the pointer type with element t. For example, if t represents type Foo, PtrTo(t) represents *Foo.

PtrTo is the old spelling of PointerTo. The two functions behave identically.

func SliceOf 

func SliceOf(t Type) Type

SliceOf returns the slice type with element type t. For example, if t represents int, SliceOf(t) represents []int.

func TypeOf 

func TypeOf(i any) Type

TypeOf returns the reflection Type that represents the dynamic type of i. If i is a nil interface value, TypeOf returns nil.

type Value 

type Value struct {
	// contains filtered or unexported fields
}

Value is the reflection interface to a Go value.

Not all methods apply to all kinds of values. Restrictions, if any, are noted in the documentation for each method. Use the Kind method to find out the kind of value before calling kind-specific methods. Calling a method inappropriate to the kind of type causes a run time panic.

The zero Value represents no value. Its IsValid method returns false, its Kind method returns Invalid, its String method returns "<invalid Value>", and all other methods panic. Most functions and methods never return an invalid value. If one does, its documentation states the conditions explicitly.

A Value can be used concurrently by multiple goroutines provided that the underlying Go value can be used concurrently for the equivalent direct operations.

To compare two Values, compare the results of the Interface method. Using == on two Values does not compare the underlying values they represent.

func Append 

func Append(s Value, x ...Value) Value

Append appends the values x to a slice s and returns the resulting slice. As in Go, each x's value must be assignable to the slice's element type.

func AppendSlice 

func AppendSlice(s, t Value) Value

AppendSlice appends a slice t to a slice s and returns the resulting slice. The slices s and t must have the same element type.

func MakeMap added in v0.9.8 

func MakeMap(typ Type) Value

MakeMap creates a new map with the specified type.

func MakeMapWithSize added in v0.9.8 

func MakeMapWithSize(typ Type, n int) Value

MakeMapWithSize creates a new map with the specified type and initial space for approximately n elements.

func MakeSlice added in v0.9.8 

func MakeSlice(typ Type, len, cap int) Value

MakeSlice creates a new zero-initialized slice value for the specified slice type, length, and capacity.

func New 

func New(typ Type) Value

New returns a Value representing a pointer to a new zero value for the specified type. That is, the returned Value's Type is PointerTo(typ).

func NewAt 

func NewAt(typ Type, p unsafe.Pointer) Value

NewAt returns a Value representing a pointer to a value of the specified type, using p as that pointer.

func ValueOf 

func ValueOf(i any) Value

ValueOf returns a new Value initialized to the concrete value stored in the interface i. ValueOf(nil) returns the zero Value.

func Zero 

func Zero(typ Type) Value

Zero returns a Value representing the zero value for the specified type. The result is different from the zero value of the Value struct, which represents no value at all. For example, Zero(TypeOf(42)) returns a Value with Kind Int and value 0. The returned value is neither addressable nor settable.

func (Value) Addr 

func (v Value) Addr() Value

Addr returns a pointer value representing the address of v. It panics if CanAddr() returns false. Addr is typically used to obtain a pointer to a struct field or slice element in order to call a method that requires a pointer receiver.

func (Value) Bool 

func (v Value) Bool() bool

Bool returns v's underlying value. It panics if v's kind is not Bool.

func (Value) Bytes 

func (v Value) Bytes() []byte

Bytes returns v's underlying value. It panics if v's underlying value is not a slice of bytes or an addressable array of bytes.

func (Value) Call added in v0.9.8 

func (v Value) Call(in []Value) []Value

Call calls the function v with the input arguments in. For example, if len(in) == 3, v.Call(in) represents the Go call v(in[0], in[1], in[2]). Call panics if v's Kind is not Func. It returns the output results as Values. As in Go, each input argument must be assignable to the type of the function's corresponding input parameter. If v is a variadic function, Call creates the variadic slice parameter itself, copying in the corresponding values.

func (Value) CallSlice added in v0.9.8 

func (v Value) CallSlice(in []Value) []Value

CallSlice calls the variadic function v with the input arguments in, assigning the slice in[len(in)-1] to v's final variadic argument. For example, if len(in) == 3, v.CallSlice(in) represents the Go call v(in[0], in[1], in[2]...). CallSlice panics if v's Kind is not Func or if v is not variadic. It returns the output results as Values. As in Go, each input argument must be assignable to the type of the function's corresponding input parameter.

func (Value) CanAddr added in v0.9.0 

func (v Value) CanAddr() bool

CanAddr reports whether the value's address can be obtained with Addr. Such values are called addressable. A value is addressable if it is an element of a slice, an element of an addressable array, a field of an addressable struct, or the result of dereferencing a pointer. If CanAddr returns false, calling Addr will panic.

func (Value) CanComplex added in v0.9.0 

func (v Value) CanComplex() bool

CanComplex reports whether Complex can be used without panicking.

func (Value) CanFloat 

func (v Value) CanFloat() bool

CanFloat reports whether Float can be used without panicking.

func (Value) CanInt 

func (v Value) CanInt() bool

CanInt reports whether Int can be used without panicking.

func (Value) CanInterface 

func (v Value) CanInterface() bool

CanInterface reports whether Interface can be used without panicking.

func (Value) CanSet added in v0.9.0 

func (v Value) CanSet() bool

CanSet reports whether the value of v can be changed. A Value can be changed only if it is addressable and was not obtained by the use of unexported struct fields. If CanSet returns false, calling Set or any type-specific setter (e.g., SetBool, SetInt) will panic.

func (Value) CanUint added in v0.9.0 

func (v Value) CanUint() bool

CanUint reports whether Uint can be used without panicking.

func (Value) Cap added in v0.9.0 

func (v Value) Cap() int

Cap returns v's capacity. It panics if v's Kind is not Array, Chan, Slice or pointer to Array.

func (Value) Close added in v0.9.0 

func (v Value) Close()

Close closes the channel v. It panics if v's Kind is not Chan.

func (Value) Complex added in v0.9.0 

func (v Value) Complex() complex128

Complex returns v's underlying value, as a complex128. It panics if v's Kind is not Complex64 or Complex128

func (Value) Elem added in v0.9.0 

func (v Value) Elem() Value

Elem returns the value that the interface v contains or that the pointer v points to. It panics if v's Kind is not Interface or Pointer. It returns the zero Value if v is nil.

func (Value) Field added in v0.9.0 

func (v Value) Field(i int) Value

Field returns the i'th field of the struct v. It panics if v's Kind is not Struct or i is out of range.

func (Value) FieldByIndex added in v0.9.0 

func (v Value) FieldByIndex(index []int) Value

FieldByIndex returns the nested field corresponding to index. It panics if evaluation requires stepping through a nil pointer or a field that is not a struct.

func (Value) FieldByIndexErr added in v0.9.0 

func (v Value) FieldByIndexErr(index []int) (Value, error)

FieldByIndexErr returns the nested field corresponding to index. It returns an error if evaluation requires stepping through a nil pointer, but panics if it must step through a field that is not a struct.

func (Value) FieldByName added in v0.9.0 

func (v Value) FieldByName(name string) Value

FieldByName returns the struct field with the given name. It returns the zero Value if no field was found. It panics if v's Kind is not struct.

func (Value) FieldByNameFunc added in v0.9.0 

func (v Value) FieldByNameFunc(match func(string) bool) Value

FieldByNameFunc returns the struct field with a name that satisfies the match function. It panics if v's Kind is not struct. It returns the zero Value if no field was found.

func (Value) Float 

func (v Value) Float() float64

Float returns v's underlying value, as a float64. It panics if v's Kind is not Float32 or Float64

func (Value) Grow 

func (v Value) Grow(n int)

Grow increases the slice's capacity, if necessary, to guarantee space for another n elements. After Grow(n), at least n elements can be appended to the slice without another allocation.

It panics if v's Kind is not a Slice or if n is negative or too large to allocate the memory.

func (Value) Index 

func (v Value) Index(i int) Value

Index returns v's i'th element. It panics if v's Kind is not Array, Slice, or String or i is out of range.

func (Value) Int 

func (v Value) Int() int64

Int returns v's underlying value, as an int64. It panics if v's Kind is not Int, Int8, Int16, Int32, or Int64.

func (Value) Interface 

func (v Value) Interface() (i any)

Interface returns v's current value as an interface{}. It is equivalent to: 

var i interface{} = (v's underlying value)

It panics if the Value was obtained by accessing unexported struct fields.

func (Value) InterfaceData deprecated 

func (v Value) InterfaceData() [2]uintptr

InterfaceData returns a pair of unspecified uintptr values. It panics if v's Kind is not Interface.

In earlier versions of Go, this function returned the interface's value as a uintptr pair. As of Go 1.4, the implementation of interface values precludes any defined use of InterfaceData.

Deprecated: The memory representation of interface values is not compatible with InterfaceData.

func (Value) IsNil 

func (v Value) IsNil() bool

IsNil reports whether its argument v is nil. The argument must be a chan, func, interface, map, pointer, or slice value; if it is not, IsNil panics. Note that IsNil is not always equivalent to a regular comparison with nil in Go. For example, if v was created by calling ValueOf with an uninitialized interface variable i, i==nil will be true but v.IsNil will panic as v will be the zero Value.

func (Value) IsValid 

func (v Value) IsValid() bool

IsValid reports whether v represents a value. It returns false if v is the zero Value. If IsValid returns false, all other methods except String panic. Most functions and methods never return an invalid Value. If one does, its documentation states the conditions explicitly.

func (Value) IsZero 

func (v Value) IsZero() bool

IsZero reports whether v is the zero value for its type. It panics if the argument is invalid.

func (Value) Kind 

func (v Value) Kind() Kind

Kind returns v's Kind. If v is the zero Value (IsValid returns false), Kind returns Invalid.

func (Value) Len 

func (v Value) Len() int

Len returns v's length. It panics if v's Kind is not Array, Chan, Map, Slice, String, or pointer to Array.

func (Value) MapIndex added in v0.9.8 

func (v Value) MapIndex(key Value) Value

MapIndex returns the value associated with key in the map v. It panics if v's Kind is not Map. It returns the zero Value if key is not found in the map or if v represents a nil map. As in Go, the key's value must be assignable to the map's key type.

func (Value) MapKeys added in v0.9.8 

func (v Value) MapKeys() []Value

MapKeys returns a slice containing all the keys present in the map, in unspecified order. It panics if v's Kind is not Map. It returns an empty slice if v represents a nil map.

func (Value) MapRange added in v0.9.8 

func (v Value) MapRange() *MapIter

MapRange returns a range iterator for a map. It panics if v's Kind is not Map.

Call Next to advance the iterator, and Key/Value to access each entry. Next returns false when the iterator is exhausted. MapRange follows the same iteration semantics as a range statement.

Example: 

iter := reflect.ValueOf(m).MapRange()
for iter.Next() {
	k := iter.Key()
	v := iter.Value()
	...
}

func (Value) Method added in v0.9.8 

func (v Value) Method(i int) Value

Method returns a function value corresponding to v's i'th method. The arguments to a Call on the returned function should not include a receiver; the returned function will always use v as the receiver. Method panics if i is out of range or if v is a nil interface value.

func (Value) MethodByName added in v0.9.8 

func (v Value) MethodByName(name string) Value

MethodByName returns a function value corresponding to the method of v with the given name. The arguments to a Call on the returned function should not include a receiver; the returned function will always use v as the receiver. It returns the zero Value if no method was found.

func (Value) NumField added in v0.9.8 

func (v Value) NumField() int

NumField returns the number of fields in the struct v. It panics if v's Kind is not Struct.

func (Value) NumMethod added in v0.9.8 

func (v Value) NumMethod() int

NumMethod returns the number of methods in the value's method set.

For a non-interface type, it returns the number of exported methods.

For an interface type, it returns the number of exported and unexported methods.

func (Value) Pointer added in v0.9.0 

func (v Value) Pointer() uintptr

Pointer returns v's value as a uintptr. It panics if v's Kind is not Chan, Func, Map, Pointer, Slice, or UnsafePointer.

If v's Kind is Func, the returned pointer is an underlying code pointer, but not necessarily enough to identify a single function uniquely. The only guarantee is that the result is zero if and only if v is a nil func Value.

If v's Kind is Slice, the returned pointer is to the first element of the slice. If the slice is nil the returned value is 0. If the slice is empty but non-nil the return value is non-zero.

It's preferred to use uintptr(Value.UnsafePointer()) to get the equivalent result.

func (Value) Recv added in v0.9.0 

func (v Value) Recv() (x Value, ok bool)

Recv receives and returns a value from the channel v. It panics if v's Kind is not Chan. The receive blocks until a value is ready. The boolean value ok is true if the value x corresponds to a send on the channel, false if it is a zero value received because the channel is closed.

func (Value) Send added in v0.9.0 

func (v Value) Send(x Value)

Send sends x on the channel v. It panics if v's kind is not Chan or if x's type is not the same type as v's element type. As in Go, x's value must be assignable to the channel's element type.

func (Value) Set 

func (v Value) Set(x Value)

Set assigns x to the value v. It panics if CanSet returns false. As in Go, x's value must be assignable to v's type and must not be derived from an unexported field.

func (Value) SetBool 

func (v Value) SetBool(x bool)

SetBool sets v's underlying value. It panics if v's Kind is not Bool or if CanSet() is false.

func (Value) SetBytes 

func (v Value) SetBytes(x []byte)

SetBytes sets v's underlying value. It panics if v's underlying value is not a slice of bytes.

func (Value) SetCap added in v0.9.0 

func (v Value) SetCap(n int)

SetCap sets v's capacity to n. It panics if v's Kind is not Slice or if n is smaller than the length or greater than the capacity of the slice.

func (Value) SetComplex 

func (v Value) SetComplex(x complex128)

SetComplex sets v's underlying value to x. It panics if v's Kind is not Complex64 or Complex128, or if CanSet() is false.

func (Value) SetFloat 

func (v Value) SetFloat(x float64)

SetFloat sets v's underlying value to x. It panics if v's Kind is not Float32 or Float64, or if CanSet() is false.

func (Value) SetInt 

func (v Value) SetInt(x int64)

SetInt sets v's underlying value to x. It panics if v's Kind is not Int, Int8, Int16, Int32, or Int64, or if CanSet() is false.

func (Value) SetIterKey added in v0.9.8 

func (v Value) SetIterKey(iter *MapIter)

SetIterKey assigns to v the key of iter's current map entry. It is equivalent to v.Set(iter.Key()), but it avoids allocating a new Value. As in Go, the key must be assignable to v's type and must not be derived from an unexported field.

func (Value) SetIterValue added in v0.9.8 

func (v Value) SetIterValue(iter *MapIter)

SetIterValue assigns to v the value of iter's current map entry. It is equivalent to v.Set(iter.Value()), but it avoids allocating a new Value. As in Go, the value must be assignable to v's type and must not be derived from an unexported field.

func (Value) SetLen added in v0.9.0 

func (v Value) SetLen(n int)

SetLen sets v's length to n. It panics if v's Kind is not Slice or if n is negative or greater than the capacity of the slice.

func (Value) SetMapIndex added in v0.9.0 

func (v Value) SetMapIndex(key, elem Value)

SetMapIndex sets the element associated with key in the map v to elem. It panics if v's Kind is not Map. If elem is the zero Value, SetMapIndex deletes the key from the map. Otherwise if v holds a nil map, SetMapIndex will panic. As in Go, key's elem must be assignable to the map's key type, and elem's value must be assignable to the map's elem type.

func (Value) SetPointer added in v0.9.0 

func (v Value) SetPointer(x unsafe.Pointer)

SetPointer sets the unsafe.Pointer value v to x. It panics if v's Kind is not UnsafePointer.

func (Value) SetString added in v0.9.0 

func (v Value) SetString(x string)

SetString sets v's underlying value to x. It panics if v's Kind is not String or if CanSet() is false.

func (Value) SetUint added in v0.9.0 

func (v Value) SetUint(x uint64)

SetUint sets v's underlying value to x. It panics if v's Kind is not Uint, Uintptr, Uint8, Uint16, Uint32, or Uint64, or if CanSet() is false.

func (Value) SetZero 

func (v Value) SetZero()

SetZero sets v to be the zero value of v's type. It panics if CanSet returns false.

func (Value) Slice added in v0.9.0 

func (v Value) Slice(i, j int) Value

Slice returns v[i:j]. It panics if v's Kind is not Array, Slice or String, or if v is an unaddressable array, or if the indexes are out of bounds.

func (Value) Slice3 added in v0.9.0 

func (v Value) Slice3(i, j, k int) Value

Slice3 is the 3-index form of the slice operation: it returns v[i:j:k]. It panics if v's Kind is not Array or Slice, or if v is an unaddressable array, or if the indexes are out of bounds.

func (Value) String added in v0.9.0 

func (v Value) String() string

String returns the string v's underlying value, as a string. String is a special case because of Go's String method convention. Unlike the other getters, it does not panic if v's Kind is not String. Instead, it returns a string of the form "<T value>" where T is v's type. The fmt package treats Values specially. It does not call their String method implicitly but instead prints the concrete values they hold.

func (Value) TryRecv added in v0.9.0 

func (v Value) TryRecv() (x Value, ok bool)

TryRecv attempts to receive a value from the channel v but will not block. It panics if v's Kind is not Chan. If the receive delivers a value, x is the transferred value and ok is true. If the receive cannot finish without blocking, x is the zero Value and ok is false. If the channel is closed, x is the zero value for the channel's element type and ok is false.

func (Value) TrySend added in v0.9.0 

func (v Value) TrySend(x Value) bool

TrySend attempts to send x on the channel v but will not block. It panics if v's Kind is not Chan. It reports whether the value was sent. As in Go, x's value must be assignable to the channel's element type.

func (Value) Type added in v0.9.0 

func (v Value) Type() Type

Type returns v's type.

func (Value) Uint added in v0.9.0 

func (v Value) Uint() uint64

Uint returns v's underlying value, as a uint64. It panics if v's Kind is not Uint, Uintptr, Uint8, Uint16, Uint32, or Uint64.

func (Value) UnsafeAddr added in v0.9.0 

func (v Value) UnsafeAddr() uintptr

UnsafeAddr returns a pointer to v's data, as a uintptr. It panics if v is not addressable.

It's preferred to use uintptr(Value.Addr().UnsafePointer()) to get the equivalent result.

func (Value) UnsafePointer added in v0.9.0 

func (v Value) UnsafePointer() unsafe.Pointer

UnsafePointer returns v's value as a unsafe.Pointer. It panics if v's Kind is not Chan, Func, Map, Pointer, Slice, or UnsafePointer.

If v's Kind is Func, the returned pointer is an underlying code pointer, but not necessarily enough to identify a single function uniquely. The only guarantee is that the result is zero if and only if v is a nil func Value.

If v's Kind is Slice, the returned pointer is to the first element of the slice. If the slice is nil the returned value is nil. If the slice is empty but non-nil the return value is non-nil.

type ValueError 

type ValueError struct {
	Method string
	Kind   Kind
}

A ValueError occurs when a Value method is invoked on a Value that does not support it. Such cases are documented in the description of each method.

func (*ValueError) Error 

func (e *ValueError) Error() string

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