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Intercept provided values #409

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6 changes: 6 additions & 0 deletions callback.go
Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,8 @@

package dig

import "reflect"

// CallbackInfo contains information about a provided function or decorator
// called by Dig, and is passed to a [Callback] registered with
// [WithProviderCallback] or [WithDecoratorCallback].
Expand All @@ -32,6 +34,10 @@ type CallbackInfo struct {
// function, if any. When used in conjunction with [RecoverFromPanics],
// this will be set to a [PanicError] when the function panics.
Error error

// Values contains all values constructed by the [Callback]'s
// associated function.
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Given the discussion, let's add some explicit documentation here that mentions the undefined results of modifying these values.

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I updated the comment!

Values []reflect.Value
}

// Callback is a function that can be registered with a provided function
Expand Down
10 changes: 8 additions & 2 deletions constructor.go
Original file line number Diff line number Diff line change
Expand Up @@ -160,12 +160,15 @@ func (n *constructorNode) Call(c containerStore) (err error) {
}
}

var values []reflect.Value

if n.callback != nil {
// Wrap in separate func to include PanicErrors
defer func() {
n.callback(CallbackInfo{
Name: fmt.Sprintf("%v.%v", n.location.Package, n.location.Name),
Error: err,
Name: fmt.Sprintf("%v.%v", n.location.Package, n.location.Name),
Error: err,
Values: values,
})
}()
}
Expand All @@ -192,6 +195,9 @@ func (n *constructorNode) Call(c containerStore) (err error) {
// the rest of the graph to instantiate the dependencies of this
// container.
receiver.Commit(n.s)

values = n.resultList.Values(results)

n.called = true
return nil
}
Expand Down
9 changes: 7 additions & 2 deletions decorate.go
Original file line number Diff line number Diff line change
Expand Up @@ -121,12 +121,15 @@ func (n *decoratorNode) Call(s containerStore) (err error) {
}
}

var values []reflect.Value

if n.callback != nil {
// Wrap in separate func to include PanicErrors
defer func() {
n.callback(CallbackInfo{
Name: fmt.Sprintf("%v.%v", n.location.Package, n.location.Name),
Error: err,
Name: fmt.Sprintf("%v.%v", n.location.Package, n.location.Name),
Error: err,
Values: values,
})
}()
}
Expand All @@ -146,6 +149,8 @@ func (n *decoratorNode) Call(s containerStore) (err error) {
if err = n.results.ExtractList(n.s, true /* decorated */, results); err != nil {
return err
}
values = n.results.Values(results)

n.state = decoratorCalled
return nil
}
Expand Down
191 changes: 191 additions & 0 deletions dig_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -1685,6 +1685,14 @@ func TestRecoverFromPanic(t *testing.T) {

func giveInt() int { return 5 }

type providedInterface interface {
Start()
}

type providedStruct struct{}

func (providedStruct) Start() {}

func TestCallback(t *testing.T) {
t.Run("no errors", func(t *testing.T) {
var (
Expand All @@ -1698,6 +1706,9 @@ func TestCallback(t *testing.T) {
dig.WithProviderCallback(func(ci dig.CallbackInfo) {
assert.Equal(t, "go.uber.org/dig_test.giveInt", ci.Name)
assert.NoError(t, ci.Error)
assert.Len(t, ci.Values, 1)
assert.True(t, ci.Values[0].CanInt())
assert.EqualValues(t, 5, ci.Values[0].Int())
provideCallbackCalled = true
}),
)
Expand All @@ -1706,6 +1717,9 @@ func TestCallback(t *testing.T) {
dig.WithDecoratorCallback(func(ci dig.CallbackInfo) {
assert.Equal(t, "go.uber.org/dig_test.TestCallback.func1.2", ci.Name)
assert.NoError(t, ci.Error)
assert.Len(t, ci.Values, 1)
assert.True(t, ci.Values[0].CanInt())
assert.EqualValues(t, 10, ci.Values[0].Int())
decorateCallbackCalled = true
}),
)
Expand All @@ -1727,6 +1741,7 @@ func TestCallback(t *testing.T) {
dig.WithProviderCallback(func(ci dig.CallbackInfo) {
assert.Equal(t, "go.uber.org/dig_test.TestCallback.func2.1", ci.Name)
assert.ErrorContains(t, ci.Error, "terrible callback sadness")
assert.Nil(t, ci.Values)
called = true
}),
)
Expand All @@ -1747,6 +1762,7 @@ func TestCallback(t *testing.T) {
dig.WithDecoratorCallback(func(ci dig.CallbackInfo) {
assert.Equal(t, "go.uber.org/dig_test.TestCallback.func3.1", ci.Name)
assert.ErrorContains(t, ci.Error, "terrible callback sadness")
assert.Nil(t, ci.Values)
called = true
}),
)
Expand All @@ -1766,6 +1782,7 @@ func TestCallback(t *testing.T) {
var pe dig.PanicError
assert.True(t, errors.As(ci.Error, &pe))
assert.ErrorContains(t, ci.Error, "panic: \"unreal misfortune\"")
assert.Nil(t, ci.Values)
called = true
}),
)
Expand All @@ -1786,6 +1803,7 @@ func TestCallback(t *testing.T) {
var pe dig.PanicError
assert.True(t, errors.As(ci.Error, &pe))
assert.ErrorContains(t, ci.Error, "panic: \"unreal misfortune\"")
assert.Nil(t, ci.Values)

called = true
}),
Expand All @@ -1794,6 +1812,179 @@ func TestCallback(t *testing.T) {
c.Invoke(func(int) {})
assert.True(t, called)
})
t.Run("callback receives primitives", func(t *testing.T) {
var providerCallbackCalled bool

c := digtest.New(t)

c.RequireProvide(giveInt, dig.WithProviderCallback(func(ci dig.CallbackInfo) {
assert.Equal(t, "go.uber.org/dig_test.giveInt", ci.Name)
assert.Nil(t, ci.Error)
assert.Len(t, ci.Values, 1)
assert.True(t, ci.Values[0].CanInt())
assert.EqualValues(t, 5, ci.Values[0].Int())
providerCallbackCalled = true
}))

c.RequireInvoke(func(a int) {
assert.Equal(t, 5, a)
})

assert.True(t, providerCallbackCalled)
})

t.Run("callback works with value groups", func(t *testing.T) {
var providerCallbackCalledTimes int

c := digtest.New(t)

c.RequireProvide(giveInt, dig.Group("test"), dig.WithProviderCallback(func(ci dig.CallbackInfo) {
assert.NotEmpty(t, ci.Name)
assert.Nil(t, ci.Error)
assert.Len(t, ci.Values, 1)
assert.True(t, ci.Values[0].CanInt())
assert.EqualValues(t, 5, ci.Values[0].Int())
providerCallbackCalledTimes++
}))
c.RequireProvide(func() int { return 6 }, dig.Group("test"), dig.WithProviderCallback(func(ci dig.CallbackInfo) {
assert.NotEmpty(t, ci.Name)
assert.Nil(t, ci.Error)
assert.Len(t, ci.Values, 1)
assert.True(t, ci.Values[0].CanInt())
assert.EqualValues(t, 6, ci.Values[0].Int())
providerCallbackCalledTimes++
}))

type params struct {
dig.In

Value []int `group:"test"`
}

c.RequireInvoke(func(a params) {
assert.ElementsMatch(t, []int{5, 6}, a.Value)
})

assert.Equal(t, 2, providerCallbackCalledTimes)
})

t.Run("callback works with interfaces", func(t *testing.T) {
var providerCallbackCalled bool

var gave providedInterface

c := digtest.New(t)

c.RequireProvide(
func() providedInterface {
gave = &providedStruct{}
return gave
},
dig.WithProviderCallback(func(ci dig.CallbackInfo) {
assert.NotEmpty(t, ci.Name)
assert.Nil(t, ci.Error)
assert.Len(t, ci.Values, 1)
assert.True(t, ci.Values[0].CanInterface())
_, ok := ci.Values[0].Interface().(providedInterface)
assert.True(t, ok)
providerCallbackCalled = true
}),
)

c.RequireInvoke(func(got providedInterface) {
assert.Equal(t, gave, got)
})

assert.True(t, providerCallbackCalled)
})

t.Run("callback works with provider returning multiple values", func(t *testing.T) {
var providerCallbackCalled bool

c := digtest.New(t)

c.RequireProvide(
func() (string, int) {
return "five", 5
},
dig.WithProviderCallback(func(ci dig.CallbackInfo) {
assert.NotEmpty(t, ci.Name)
assert.Nil(t, ci.Error)
assert.Len(t, ci.Values, 2)
assert.EqualValues(t, "five", ci.Values[0].String())
assert.EqualValues(t, 5, ci.Values[1].Int())
providerCallbackCalled = true
}),
)

c.RequireInvoke(func(s string, i int) {
assert.Equal(t, "five", s)
assert.Equal(t, 5, i)
})

assert.True(t, providerCallbackCalled)
})

t.Run("callback does not receive nil error value with providers that can fail", func(t *testing.T) {
var providerCallbackCalled bool

c := digtest.New(t)

c.RequireProvide(
func() (string, int, error) {
return "five", 5, nil
},
dig.WithProviderCallback(func(ci dig.CallbackInfo) {
assert.NotEmpty(t, ci.Name)
assert.Nil(t, ci.Error)
assert.Len(t, ci.Values, 2)
assert.EqualValues(t, "five", ci.Values[0].String())
assert.EqualValues(t, 5, ci.Values[1].Int())
providerCallbackCalled = true
}),
)

c.RequireInvoke(func(s string, i int) {
assert.Equal(t, "five", s)
assert.Equal(t, 5, i)
})

assert.True(t, providerCallbackCalled)
})

t.Run("object values are exploded into single values", func(t *testing.T) {
var containerCallbackCalled bool

c := digtest.New(t)

type out struct {
dig.Out

String string
Int int
}

c.RequireProvide(
func() (out, error) {
return out{String: "five", Int: 5}, nil
},
dig.WithProviderCallback(func(ci dig.CallbackInfo) {
assert.NotEmpty(t, ci.Name)
assert.Nil(t, ci.Error)
assert.Len(t, ci.Values, 2)
assert.EqualValues(t, "five", ci.Values[0].String())
assert.EqualValues(t, 5, ci.Values[1].Int())
containerCallbackCalled = true
}),
)

c.RequireInvoke(func(s string, i int) {
assert.Equal(t, "five", s)
assert.Equal(t, 5, i)
})

assert.True(t, containerCallbackCalled)
})
}

func TestProvideConstructorErrors(t *testing.T) {
Expand Down
34 changes: 34 additions & 0 deletions result.go
Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,9 @@
// This MAY panic if the result does not consume a single value.
Extract(containerWriter, bool, reflect.Value)

// GetValues returns all values contained in a result.
GetValues(reflect.Value) []reflect.Value

// DotResult returns a slice of dot.Result(s).
DotResult() []*dot.Result
}
Expand Down Expand Up @@ -259,6 +262,21 @@
return nil
}

func (rl resultList) GetValues(values reflect.Value) []reflect.Value {
digerror.BugPanicf("resultList.GetValues() must never be called")
panic("") // Unreachable, as BugPanicf above will panic.

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}

func (rl resultList) Values(values []reflect.Value) []reflect.Value {
result := make([]reflect.Value, 0)
for i, v := range values {
if resultIdx := rl.resultIndexes[i]; resultIdx >= 0 {
result = append(result, rl.Results[resultIdx].GetValues(v)...)
}
}
return result
}

// resultSingle is an explicit value produced by a constructor, optionally
// with a name.
//
Expand Down Expand Up @@ -336,6 +354,10 @@
}
}

func (rs resultSingle) GetValues(v reflect.Value) []reflect.Value {
return []reflect.Value{v}
}

// resultObject is a dig.Out struct where each field is another result.
//
// This object is not added to the graph. Its fields are interpreted as
Expand Down Expand Up @@ -388,6 +410,14 @@
}
}

func (ro resultObject) GetValues(v reflect.Value) []reflect.Value {
res := make([]reflect.Value, 0)
for _, f := range ro.Fields {
res = append(res, v.Field(f.FieldIndex))
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}
return res
}

// resultObjectField is a single field inside a dig.Out struct.
type resultObjectField struct {
// Name of the field in the struct.
Expand Down Expand Up @@ -533,3 +563,7 @@
cw.submitGroupedValue(rt.Group, rt.Type, v.Index(i))
}
}

func (rt resultGrouped) GetValues(v reflect.Value) []reflect.Value {
return []reflect.Value{v}
}
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