Creating a struct that contains list types in go

-2

I have created a struct, this struct has contains two list types within it. When I try to instantiate my struct I receive the error

cannot use list.New() (type *list.List) as type list.List in field value

I am using the golang playground

The struct

type myStruct struct {

    name string

    messages list.List

    users list.List

    lastUsed time.Time

}

Instantiating the struct

var myVar = myStruct{"hello", list.New(), list.New(), time.Now()}

asked Jan 2 at 8:50

Jacob

70324

The error message is pretty clear: You're trying to assign a pointer to a concrete value.

– Flimzy
Jan 2 at 9:17

@Flimzy The error message doesn't mention a pointer or a concrete value, so it wasn't clear to me. I understand now that the * means pointer, but it's been a few years since I've worked with pointers.

– Jacob
Jan 2 at 9:19

1

Well, it does mention those. *list.List means pointer, list.List means concrete value. If these concepts are new to you, you should start with A Tour of Go.

– Flimzy
Jan 2 at 9:21

@Flimzy They are not new, I am just rusty using them, I've already done that tour.

– Jacob
Jan 2 at 9:23

add a comment |

-2

I have created a struct, this struct has contains two list types within it. When I try to instantiate my struct I receive the error

cannot use list.New() (type *list.List) as type list.List in field value

I am using the golang playground

The struct

type myStruct struct {

    name string

    messages list.List

    users list.List

    lastUsed time.Time

}

Instantiating the struct

var myVar = myStruct{"hello", list.New(), list.New(), time.Now()}

asked Jan 2 at 8:50

Jacob

70324

The error message is pretty clear: You're trying to assign a pointer to a concrete value.

– Flimzy
Jan 2 at 9:17

@Flimzy The error message doesn't mention a pointer or a concrete value, so it wasn't clear to me. I understand now that the * means pointer, but it's been a few years since I've worked with pointers.

– Jacob
Jan 2 at 9:19

1

Well, it does mention those. *list.List means pointer, list.List means concrete value. If these concepts are new to you, you should start with A Tour of Go.

– Flimzy
Jan 2 at 9:21

@Flimzy They are not new, I am just rusty using them, I've already done that tour.

– Jacob
Jan 2 at 9:23

add a comment |

-2

I have created a struct, this struct has contains two list types within it. When I try to instantiate my struct I receive the error

cannot use list.New() (type *list.List) as type list.List in field value

I am using the golang playground

The struct

type myStruct struct {

    name string

    messages list.List

    users list.List

    lastUsed time.Time

}

Instantiating the struct

var myVar = myStruct{"hello", list.New(), list.New(), time.Now()}

asked Jan 2 at 8:50

Jacob

70324

I have created a struct, this struct has contains two list types within it. When I try to instantiate my struct I receive the error

cannot use list.New() (type *list.List) as type list.List in field value

I am using the golang playground

The struct

type myStruct struct {

    name string

    messages list.List

    users list.List

    lastUsed time.Time

}

Instantiating the struct

var myVar = myStruct{"hello", list.New(), list.New(), time.Now()}

list go struct

asked Jan 2 at 8:50

Jacob

70324

asked Jan 2 at 8:50

Jacob

70324

asked Jan 2 at 8:50

Jacob

70324

asked Jan 2 at 8:50

Jacob

70324

asked Jan 2 at 8:50

Jacob

70324

The error message is pretty clear: You're trying to assign a pointer to a concrete value.

– Flimzy
Jan 2 at 9:17

@Flimzy The error message doesn't mention a pointer or a concrete value, so it wasn't clear to me. I understand now that the * means pointer, but it's been a few years since I've worked with pointers.

– Jacob
Jan 2 at 9:19

1

Well, it does mention those. *list.List means pointer, list.List means concrete value. If these concepts are new to you, you should start with A Tour of Go.

– Flimzy
Jan 2 at 9:21

@Flimzy They are not new, I am just rusty using them, I've already done that tour.

– Jacob
Jan 2 at 9:23

add a comment |

The error message is pretty clear: You're trying to assign a pointer to a concrete value.

– Flimzy
Jan 2 at 9:17

@Flimzy The error message doesn't mention a pointer or a concrete value, so it wasn't clear to me. I understand now that the * means pointer, but it's been a few years since I've worked with pointers.

– Jacob
Jan 2 at 9:19

1

Well, it does mention those. *list.List means pointer, list.List means concrete value. If these concepts are new to you, you should start with A Tour of Go.

– Flimzy
Jan 2 at 9:21

@Flimzy They are not new, I am just rusty using them, I've already done that tour.

– Jacob
Jan 2 at 9:23

The error message is pretty clear: You're trying to assign a pointer to a concrete value.

– Flimzy
Jan 2 at 9:17

@Flimzy The error message doesn't mention a pointer or a concrete value, so it wasn't clear to me. I understand now that the * means pointer, but it's been a few years since I've worked with pointers.

– Jacob
Jan 2 at 9:19

Well, it does mention those. *list.List means pointer, list.List means concrete value. If these concepts are new to you, you should start with A Tour of Go.

– Flimzy
Jan 2 at 9:21

@Flimzy They are not new, I am just rusty using them, I've already done that tour.

– Jacob
Jan 2 at 9:23

add a comment |

2 Answers
2

active

oldest

votes

list.New() returns a pointer *List, while myStruct announce its fields as List.

func New() *List

messages and users should be *list.List

type myStruct struct {

    name string

    messages *list.List

    users *list.List

    lastUsed time.Time

}

Another approach according to your need, u can just initialize the struct as below:

var myVar = myStruct{"hello", *list.New(), *list.New(), time.Now()}

edited Jan 2 at 9:20

answered Jan 2 at 9:08

Bob Fred

2015

Thanks, will using pointers to lists cause any problems? My original intention was to just use a list and not use a pointer. Is there a way to pass a new list to the struct instead of passing a pointer?

– Jacob
Jan 2 at 9:15

1

@Jacob edited answer.

– Bob Fred
Jan 2 at 9:26

So now your dereferencing the list.New() when you create it, so that you pass the actual list into the struct, is that correct?

– Jacob
Jan 2 at 10:41

You have to remove the '*' from the struct if you add it in the function call. I'm not sure which one I should be using. The struct is going to be a chatroom, that holds a list of messages and a list of users. I'm adding these chatrooms to a global list in my program. Would I want the struct to have pointers to lists, or concrete lists.

– Jacob
Jan 2 at 10:50

@Jacob see pointers vs values

– Bob Fred
Jan 2 at 11:37

add a comment |

You are creating wrong struct because go, according to list package New() method returns pointer type of list and you created list in struct without pointer.

func New() *List

So, according to doc you need to created your struct like below:

type myStruct struct {

    name string

    messages *list.List

    users *list.List

    lastUsed time.Time

}

Go Playground

answered Jan 2 at 9:11

saddam

693521

Thanks, will using pointers to lists cause any problems? My original intention was to just use a list and not use a pointer. Is there a way to pass a new list to the struct instead of passing a pointer?

– Jacob
Jan 2 at 9:16

add a comment |

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

list.New() returns a pointer *List, while myStruct announce its fields as List.

func New() *List

messages and users should be *list.List

type myStruct struct {

    name string

    messages *list.List

    users *list.List

    lastUsed time.Time

}

Another approach according to your need, u can just initialize the struct as below:

var myVar = myStruct{"hello", *list.New(), *list.New(), time.Now()}

edited Jan 2 at 9:20

answered Jan 2 at 9:08

Bob Fred

2015

Thanks, will using pointers to lists cause any problems? My original intention was to just use a list and not use a pointer. Is there a way to pass a new list to the struct instead of passing a pointer?

– Jacob
Jan 2 at 9:15

1

@Jacob edited answer.

– Bob Fred
Jan 2 at 9:26

So now your dereferencing the list.New() when you create it, so that you pass the actual list into the struct, is that correct?

– Jacob
Jan 2 at 10:41

You have to remove the '*' from the struct if you add it in the function call. I'm not sure which one I should be using. The struct is going to be a chatroom, that holds a list of messages and a list of users. I'm adding these chatrooms to a global list in my program. Would I want the struct to have pointers to lists, or concrete lists.

– Jacob
Jan 2 at 10:50

@Jacob see pointers vs values

– Bob Fred
Jan 2 at 11:37

add a comment |

list.New() returns a pointer *List, while myStruct announce its fields as List.

func New() *List

messages and users should be *list.List

type myStruct struct {

    name string

    messages *list.List

    users *list.List

    lastUsed time.Time

}

Another approach according to your need, u can just initialize the struct as below:

var myVar = myStruct{"hello", *list.New(), *list.New(), time.Now()}

edited Jan 2 at 9:20

answered Jan 2 at 9:08

Bob Fred

2015

Thanks, will using pointers to lists cause any problems? My original intention was to just use a list and not use a pointer. Is there a way to pass a new list to the struct instead of passing a pointer?

– Jacob
Jan 2 at 9:15

1

@Jacob edited answer.

– Bob Fred
Jan 2 at 9:26

So now your dereferencing the list.New() when you create it, so that you pass the actual list into the struct, is that correct?

– Jacob
Jan 2 at 10:41

You have to remove the '*' from the struct if you add it in the function call. I'm not sure which one I should be using. The struct is going to be a chatroom, that holds a list of messages and a list of users. I'm adding these chatrooms to a global list in my program. Would I want the struct to have pointers to lists, or concrete lists.

– Jacob
Jan 2 at 10:50

@Jacob see pointers vs values

– Bob Fred
Jan 2 at 11:37

add a comment |

list.New() returns a pointer *List, while myStruct announce its fields as List.

func New() *List

messages and users should be *list.List

type myStruct struct {

    name string

    messages *list.List

    users *list.List

    lastUsed time.Time

}

Another approach according to your need, u can just initialize the struct as below:

var myVar = myStruct{"hello", *list.New(), *list.New(), time.Now()}

edited Jan 2 at 9:20

answered Jan 2 at 9:08

Bob Fred

2015

list.New() returns a pointer *List, while myStruct announce its fields as List.

func New() *List

messages and users should be *list.List

type myStruct struct {

    name string

    messages *list.List

    users *list.List

    lastUsed time.Time

}

Another approach according to your need, u can just initialize the struct as below:

var myVar = myStruct{"hello", *list.New(), *list.New(), time.Now()}

edited Jan 2 at 9:20

answered Jan 2 at 9:08

Bob Fred

2015

edited Jan 2 at 9:20

answered Jan 2 at 9:08

Bob Fred

2015

answered Jan 2 at 9:08

Bob Fred

2015

answered Jan 2 at 9:08

Bob Fred

2015

Thanks, will using pointers to lists cause any problems? My original intention was to just use a list and not use a pointer. Is there a way to pass a new list to the struct instead of passing a pointer?

– Jacob
Jan 2 at 9:15

1

@Jacob edited answer.

– Bob Fred
Jan 2 at 9:26

So now your dereferencing the list.New() when you create it, so that you pass the actual list into the struct, is that correct?

– Jacob
Jan 2 at 10:41

You have to remove the '*' from the struct if you add it in the function call. I'm not sure which one I should be using. The struct is going to be a chatroom, that holds a list of messages and a list of users. I'm adding these chatrooms to a global list in my program. Would I want the struct to have pointers to lists, or concrete lists.

– Jacob
Jan 2 at 10:50

@Jacob see pointers vs values

– Bob Fred
Jan 2 at 11:37

add a comment |

Thanks, will using pointers to lists cause any problems? My original intention was to just use a list and not use a pointer. Is there a way to pass a new list to the struct instead of passing a pointer?

– Jacob
Jan 2 at 9:15

1

@Jacob edited answer.

– Bob Fred
Jan 2 at 9:26

So now your dereferencing the list.New() when you create it, so that you pass the actual list into the struct, is that correct?

– Jacob
Jan 2 at 10:41

You have to remove the '*' from the struct if you add it in the function call. I'm not sure which one I should be using. The struct is going to be a chatroom, that holds a list of messages and a list of users. I'm adding these chatrooms to a global list in my program. Would I want the struct to have pointers to lists, or concrete lists.

– Jacob
Jan 2 at 10:50

@Jacob see pointers vs values

– Bob Fred
Jan 2 at 11:37

Thanks, will using pointers to lists cause any problems? My original intention was to just use a list and not use a pointer. Is there a way to pass a new list to the struct instead of passing a pointer?

– Jacob
Jan 2 at 9:15

@Jacob edited answer.

– Bob Fred
Jan 2 at 9:26

So now your dereferencing the list.New() when you create it, so that you pass the actual list into the struct, is that correct?

– Jacob
Jan 2 at 10:41

You have to remove the '*' from the struct if you add it in the function call. I'm not sure which one I should be using. The struct is going to be a chatroom, that holds a list of messages and a list of users. I'm adding these chatrooms to a global list in my program. Would I want the struct to have pointers to lists, or concrete lists.

– Jacob
Jan 2 at 10:50

@Jacob see pointers vs values

– Bob Fred
Jan 2 at 11:37

add a comment |

You are creating wrong struct because go, according to list package New() method returns pointer type of list and you created list in struct without pointer.

func New() *List

So, according to doc you need to created your struct like below:

type myStruct struct {

    name string

    messages *list.List

    users *list.List

    lastUsed time.Time

}

Go Playground

answered Jan 2 at 9:11

saddam

693521

Thanks, will using pointers to lists cause any problems? My original intention was to just use a list and not use a pointer. Is there a way to pass a new list to the struct instead of passing a pointer?

– Jacob
Jan 2 at 9:16

add a comment |

You are creating wrong struct because go, according to list package New() method returns pointer type of list and you created list in struct without pointer.

func New() *List

So, according to doc you need to created your struct like below:

type myStruct struct {

    name string

    messages *list.List

    users *list.List

    lastUsed time.Time

}

Go Playground

answered Jan 2 at 9:11

saddam

693521

Thanks, will using pointers to lists cause any problems? My original intention was to just use a list and not use a pointer. Is there a way to pass a new list to the struct instead of passing a pointer?

– Jacob
Jan 2 at 9:16

add a comment |

You are creating wrong struct because go, according to list package New() method returns pointer type of list and you created list in struct without pointer.

func New() *List

So, according to doc you need to created your struct like below:

type myStruct struct {

    name string

    messages *list.List

    users *list.List

    lastUsed time.Time

}

Go Playground

answered Jan 2 at 9:11

saddam

693521

You are creating wrong struct because go, according to list package New() method returns pointer type of list and you created list in struct without pointer.

func New() *List

So, according to doc you need to created your struct like below:

type myStruct struct {

    name string

    messages *list.List

    users *list.List

    lastUsed time.Time

}

Go Playground

answered Jan 2 at 9:11

saddam

693521

answered Jan 2 at 9:11

saddam

693521

answered Jan 2 at 9:11

saddam

693521

answered Jan 2 at 9:11

saddam

693521

Thanks, will using pointers to lists cause any problems? My original intention was to just use a list and not use a pointer. Is there a way to pass a new list to the struct instead of passing a pointer?

– Jacob
Jan 2 at 9:16

add a comment |

Thanks, will using pointers to lists cause any problems? My original intention was to just use a list and not use a pointer. Is there a way to pass a new list to the struct instead of passing a pointer?

– Jacob
Jan 2 at 9:16

add a comment |

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