Pointer to Struct in Interface, Syntax Error? WTF?

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1

Anyone know why I am getting syntax error in this file? I have done this in other files for Phone, Email, Person, etc and its fine. But for some reason this file will not take a pointer to a struct.

package interfaces

//Go library for decoding generic map values into native Go structures.
//github.com/mitchellh/mapstructure
//Utilities for Go structs
//github.com/fatih/structs
//TODO: Create new Public repo and Combine required source from each of these two
//repos. We need to same for Struct and interface and Convert to/from each as well
//as the methods for getting / working with the field, values list, etc.
/*
func (s *struct) ToMap() Map{interface}
func (Map{interface}) FromMap() *struct

func (s *struct) FillInterface(m Map{Interface})
func (Map{interface}) FillStruct(s *struct)

..Incomplete ...

*/

/******************************************************************************************
 * Base Interface Definition															  *
 ******************************************************************************************/

//BaseStruct is only used for building/testing the base interface and will be removed.
 type BaseStruct struct {
	testInt int
	testBool bool
	testString string
	testByte []byte
	testFloat float64
	testComplex complex128
}

//BaseInterface contains the support methods required for interacting with a structure
type BaseInterface interface {

	//IsStructValid returns true|false if the current struct data is in valid and complete format
	IsStructValid() bool

	//IsStringValid returns true|false if the passed in string value is in valid and complete format
	IsStringValid(s string) bool

	//Get returns the current {model}Struct for the interface
	Get()

	//Set is given all inteface properties and they are assigned to the {model}Struct
	Set()

	//Parse takes a string and parses it to find and assign the individual struct properties of
	//the interfaces parent
	Parse(s string)

	//Format returns a formatted string for the interface
	Format()

	//ToMap Converts {model}Struct to a map[string]interface{}
	ToMap()

	//FromMap converts map[string]interface{} to {model}Struct
	FromMap()

	//ToJSON converts (model}Struct to a JSON and returns it
	ToJSON()

	//FromJSON takes a JSON and converts it to {model}Struct
	FromJSON()
}

//TestBaseInterface is only used for building/testing the base interface and will be removed.
type TestBaseInterface interface {
	*BaseStruct  //<-- Syntax Error: unexpected *, expecting method or interface name? WTF?
	BaseInterface
}

//IsStructValid returns true|false if the current struct data is in valid and complete format
func (p *BaseStruct) IsStructValid() bool {}

//IsStringValid returns true|false if the passed in string value is in valid and complete format
func (p *BaseStruct) IsStringValid(s string) {}

//Get returns the current {model}Struct for the interface
func (p *BaseStruct) Get() {}

//Set is given all inteface properties and they are assigned to the {model}Struct
func (p *BaseStruct) Set() {}

//Parse takes a string and parses it to find and assign the individual struct properties of
//the interfaces parent
func (p *BaseStruct) Parse(s string) {}

//Format returns a formatted string for the interface
func (p *BaseStruct) Format() {}

//ToMap Converts {model}Struct to a map[string]interface{}
func (p *BaseStruct) ToMap() {}

//FromMap converts map[string]interface{} to {model}Struct
func (p *BaseStruct) FromMap() {}

//ToJSON converts (model}Struct to a JSON and returns it
func (p *BaseStruct) ToJSON() {}

//FromJSON takes a JSON and converts it to {model}Struct
func (p *BaseStruct) FromJSON() {}

What am I missing here?

2

Interfaces are composed from functions and other interfaces. Not from pointers to those. So pointers are not allowed in an interface definition.

3

OK, So why is this one not giving the same error?

//EmailStruct contains a breakdown of a email
//TODO: Update to use/integrate "net/mail" and Address
type EmailStruct struct {
	Name   string //bob1234
	Domain string //gmail.com
}

//Email contains the methods for interacting with Emails (EmailStruct)
type Email interface {
	*EmailStruct
	intf.BaseInterface
	intf.DGraphInterface
	intf.BadgerInterface
	intf.FileInterface
	intf.JSONInterface
	intf.ViewInterface
}

And what would be the proper way in Golang for me to have a Struct for the “Properties” and standard interfaces for working with those properties?

Is this the proper way?

package interfaces

//Go library for decoding generic map values into native Go structures.
//github.com/mitchellh/mapstructure
//Utilities for Go structs
//github.com/fatih/structs
//TODO: Create new Public repo and Combine required source from each of these two
//repos. We need to same for Struct and interface and Convert to/from each as well
//as the methods for getting / working with the field, values list, etc.
/*
func (s *struct) ToMap() Map{interface}
func (Map{interface}) FromMap() *struct

func (s *struct) FillInterface(m Map{Interface})
func (Map{interface}) FillStruct(s *struct)

..Incomplete ...

*/

/******************************************************************************************
 * Base Interface Definition															  *
 ******************************************************************************************/

//BaseStruct is only used for building/testing the base interface and will be removed.
type BaseStruct struct {
	testInt     int
	testBool    bool
	testString  string
	testByte    []byte
	testFloat   float64
	testComplex complex128
}

//BaseInterface contains the support methods required for interacting with a structure
type BaseInterface interface {

	//IsStructValid returns true|false if the current struct data is in valid and complete format
	IsStructValid() bool

	//IsStringValid returns true|false if the passed in string value is in valid and complete format
	IsStringValid(s string) bool

	//Get returns the current {model}Struct for the interface
	Get()

	//Set is given all inteface properties and they are assigned to the {model}Struct
	Set()

	//Parse takes a string and parses it to find and assign the individual struct properties of
	//the interfaces parent
	Parse(s string)

	//Format returns a formatted string for the interface
	Format()

	//ToMap Converts {model}Struct to a map[string]interface{}
	ToMap()

	//FromMap converts map[string]interface{} to {model}Struct
	FromMap()

	//ToJSON converts (model}Struct to a JSON and returns it
	ToJSON()

	//FromJSON takes a JSON and converts it to {model}Struct
	FromJSON()
}

//TestBaseInterface is only used for building/testing the base interface and will be removed.
type TestBaseInterface struct {
	//*BaseStruct properties for this interface
	*BaseStruct

	//BaseInterface forces implementation of all methods
	BaseInterface
}

//IsStructValid returns true|false if the current struct data is in valid and complete format
func (p *BaseStruct) IsStructValid() bool { return false }

//IsStringValid returns true|false if the passed in string value is in valid and complete format
func (p *BaseStruct) IsStringValid(s string) {}

//Get returns the current {model}Struct for the interface
func (p *BaseStruct) Get() {}

//Set is given all inteface properties and they are assigned to the {model}Struct
func (p *BaseStruct) Set() {}

//Parse takes a string and parses it to find and assign the individual struct properties of
//the interfaces parent
func (p *BaseStruct) Parse(s string) {}

//Format returns a formatted string for the interface
func (p *BaseStruct) Format() {}

//ToMap Converts {model}Struct to a map[string]interface{}
func (p *BaseStruct) ToMap() {}

//FromMap converts map[string]interface{} to {model}Struct
func (p *BaseStruct) FromMap() {}

//ToJSON converts (model}Struct to a JSON and returns it
func (p *BaseStruct) ToJSON() {}

//FromJSON takes a JSON and converts it to {model}Struct
func (p *BaseStruct) FromJSON() {}
4

Not to have that kind of coupling…

type Aging interface {
  SetAge(int)
  GetAge() int
}

Then the actual implementor has to decide how to store the necessary state.

type foo int

func (f *foo) SetAge(age int) {
  f = age
}

func (f *foo) GetAge() int {
  return int(*f)
}

Also, your second example gives the same syntax error on the playground than the example from your original post…

edit

PS: My example code from above is untested and semi-pseudo code, but it should show the idea.

5

Its fine I get the idea thanks.
Actually the email one way wrong as well. it was Interface instead of struct like the others. I dont know why it was not showing syntax error but basically BaseTestInterface needs to be a struct that implements a pointer to the struct and whatever interfaces. think I got it now.

6

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