[chore] [pdata] Update comments for Value methods (#9038)

Resolves
#9025

Author: dmitryax

pdata/pcommon/value.go

@@ -129,6 +129,8 @@ func (v Value) getState() *internal.State {
 	return internal.GetValueState(internal.Value(v))
 }
 
+// FromRaw sets the value from the given raw value.
+// Calling this function on zero-initialized Value will cause a panic.
 func (v Value) FromRaw(iv any) error {
 	switch tv := iv.(type) {
 	case nil:
@@ -198,37 +200,31 @@ func (v Value) Type() ValueType {
 // Str returns the string value associated with this Value.
 // The shorter name is used instead of String to avoid implementing fmt.Stringer interface.
 // If the Type() is not ValueTypeStr then returns empty string.
-// Calling this function on zero-initialized Value will cause a panic.
 func (v Value) Str() string {
 	return v.getOrig().GetStringValue()
 }
 
 // Int returns the int64 value associated with this Value.
 // If the Type() is not ValueTypeInt then returns int64(0).
-// Calling this function on zero-initialized Value will cause a panic.
 func (v Value) Int() int64 {
 	return v.getOrig().GetIntValue()
 }
 
 // Double returns the float64 value associated with this Value.
 // If the Type() is not ValueTypeDouble then returns float64(0).
-// Calling this function on zero-initialized Value will cause a panic.
 func (v Value) Double() float64 {
 	return v.getOrig().GetDoubleValue()
 }
 
 // Bool returns the bool value associated with this Value.
 // If the Type() is not ValueTypeBool then returns false.
-// Calling this function on zero-initialized Value will cause a panic.
 func (v Value) Bool() bool {
 	return v.getOrig().GetBoolValue()
 }
 
 // Map returns the map value associated with this Value.
-// If the Type() is not ValueTypeMap then returns an invalid map. Note that using
-// such map can cause panic.
-//
-// Calling this function on zero-initialized Value will cause a panic.
+// If the function is called on zero-initialized Value or if the Type() is not ValueTypeMap
+// then it returns an invalid map. Note that using such map can cause panic.
 func (v Value) Map() Map {
 	kvlist := v.getOrig().GetKvlistValue()
 	if kvlist == nil {
@@ -238,10 +234,8 @@ func (v Value) Map() Map {
 }
 
 // Slice returns the slice value associated with this Value.
-// If the Type() is not ValueTypeSlice then returns an invalid slice. Note that using
-// such slice can cause panic.
-//
-// Calling this function on zero-initialized Value will cause a panic.
+// If the function is called on zero-initialized Value or if the Type() is not ValueTypeSlice
+// then returns an invalid slice. Note that using such slice can cause panic.
 func (v Value) Slice() Slice {
 	arr := v.getOrig().GetArrayValue()
 	if arr == nil {
@@ -251,10 +245,8 @@ func (v Value) Slice() Slice {
 }
 
 // Bytes returns the ByteSlice value associated with this Value.
-// If the Type() is not ValueTypeBytes then returns an invalid ByteSlice object. Note that using
-// such slice can cause panic.
-//
-// Calling this function on zero-initialized Value will cause a panic.
+// If the function is called on zero-initialized Value or if the Type() is not ValueTypeBytes
+// then returns an invalid ByteSlice object. Note that using such slice can cause panic.
 func (v Value) Bytes() ByteSlice {
 	bv, ok := v.getOrig().GetValue().(*otlpcommon.AnyValue_BytesValue)
 	if !ok {
@@ -325,6 +317,7 @@ func (v Value) SetEmptySlice() Slice {
 }
 
 // CopyTo copies the Value instance overriding the destination.
+// Calling this function on zero-initialized Value will cause a panic.
 func (v Value) CopyTo(dest Value) {
 	dest.getState().AssertMutable()
 	destOrig := dest.getOrig()
@@ -370,6 +363,7 @@ func (v Value) CopyTo(dest Value) {
 // AsString converts an OTLP Value object of any type to its equivalent string
 // representation. This differs from Str which only returns a non-empty value
 // if the ValueType is ValueTypeStr.
+// Calling this function on zero-initialized Value will cause a panic.
 func (v Value) AsString() string {
 	switch v.Type() {
 	case ValueTypeEmpty:

pdata/pcommon/value_test.go

@@ -556,6 +556,29 @@ func TestNewValueFromRawInvalid(t *testing.T) {
 	assert.EqualError(t, actual.FromRaw(ValueTypeDouble), "<Invalid value type pcommon.ValueType>")
 }
 
+func TestInvalidValue(t *testing.T) {
+	v := Value{}
+	assert.Equal(t, false, v.Bool())
+	assert.Equal(t, int64(0), v.Int())
+	assert.Equal(t, float64(0), v.Double())
+	assert.Equal(t, "", v.Str())
+	assert.Equal(t, ByteSlice{}, v.Bytes())
+	assert.Equal(t, Map{}, v.Map())
+	assert.Equal(t, Slice{}, v.Slice())
+	assert.Panics(t, func() { v.AsString() })
+	assert.Panics(t, func() { v.AsRaw() })
+	assert.Panics(t, func() { _ = v.FromRaw(1) })
+	assert.Panics(t, func() { v.Type() })
+	assert.Panics(t, func() { v.SetStr("") })
+	assert.Panics(t, func() { v.SetInt(0) })
+	assert.Panics(t, func() { v.SetDouble(0) })
+	assert.Panics(t, func() { v.SetBool(false) })
+	assert.Panics(t, func() { v.SetEmptyBytes() })
+	assert.Panics(t, func() { v.SetEmptyMap() })
+	assert.Panics(t, func() { v.SetEmptySlice() })
+	assert.Panics(t, func() { v.CopyTo(NewValueEmpty()) })
+}
+
 func generateTestValueMap() Value {
 	ret := NewValueMap()
 	attrMap := ret.Map()