Nuklear GUI演示未运行

Question

I am trying to run demo file at https://github.com/golang-ui/nuklear/blob/master/cmd/nk-example-sdl2/main.go but I am getting following error:

# command-line-arguments
./nk_nuclear_gui.go:72: undefined: MustAsset
./nk_nuclear_gui.go:126: undefined: flag
./nk_nuclear_gui.go:129: undefined: flag

I believe MustAsset is part of Reckon package which I installed, but error persists. Where is the problem and how can I solve it?

Edit: Both commands go build main.go and go run main.go give this error. Even go build without any filename is also giving this error as discussed in comments.

I had encountered this problem while installing nuklear package.

I am running following version on Debian Stable Linux:

go version go1.7.4 linux/amd64

I installed latest version (go version go1.10.3 linux/amd64) from https://golang.org/doc/install but the error persists.

Edit: The directory structure of go directory is as follows:

$ tree -d
.
├── pkg
│   └── linux_amd64
│       └── github.com
│           ├── golang-ui
│           │   └── nuklear
│           └── xlab
└── src
    └── github.com
        ├── go-gl
        │   ├── gl
        │   │   ├── all-core
        │   │   │   └── gl
        │   │   ├── v2.1
        │   │   │   └── gl
        │   │   ├── v3.1
        │   │   │   └── gles2
        │   │   ├── v3.2-compatibility
        │   │   │   └── gl
        │   │   ├── v3.2-core
        │   │   │   └── gl
        │   │   ├── v3.3-compatibility
        │   │   │   └── gl
        │   │   ├── v3.3-core
        │   │   │   └── gl
        │   │   ├── v4.1-compatibility
        │   │   │   └── gl
        │   │   ├── v4.1-core
        │   │   │   └── gl
        │   │   ├── v4.2-compatibility
        │   │   │   └── gl
        │   │   ├── v4.2-core
        │   │   │   └── gl
        │   │   ├── v4.3-compatibility
        │   │   │   └── gl
        │   │   ├── v4.3-core
        │   │   │   └── gl
        │   │   ├── v4.4-compatibility
        │   │   │   └── gl
        │   │   ├── v4.4-core
        │   │   │   └── gl
        │   │   ├── v4.5-compatibility
        │   │   │   └── gl
        │   │   ├── v4.5-core
        │   │   │   └── gl
        │   │   ├── v4.6-compatibility
        │   │   │   └── gl
        │   │   └── v4.6-core
        │   │       └── gl
        │   └── glfw
        │       ├── scripts
        │       ├── v3.0
        │       │   └── glfw
        │       ├── v3.1
        │       │   └── glfw
        │       │       └── glfw
        │       │           ├── deps
        │       │           │   ├── EGL
        │       │           │   ├── GL
        │       │           │   ├── glad
        │       │           │   └── KHR
        │       │           ├── include
        │       │           │   └── GLFW
        │       │           └── src
        │       └── v3.2
        │           └── glfw
        │               └── glfw
        │                   ├── deps
        │                   │   ├── glad
        │                   │   ├── KHR
        │                   │   ├── mingw
        │                   │   └── vulkan
        │                   ├── include
        │                   │   └── GLFW
        │                   └── src
        ├── golang-ui
        │   └── nuklear
        │       ├── assets
        │       ├── cmd
        │       │   ├── nk-android
        │       │   │   ├── android
        │       │   │   │   └── jni
        │       │   │   └── assets
        │       │   ├── nk-example
        │       │   │   └── assets
        │       │   └── nk-example-sdl2
        │       │       └── assets
        │       └── nk
        └── xlab
            └── closer
                └── cmd
                    ├── example
                    ├── example-error
                    ├── example-fatalln
                    └── example-panic

Answer 1

In Go, programs (and package) are based on directory. So very often, multiple source files complement each other. In this case, the MustAsset is defined in bindata.go. Therefore isolating main.go raises an error. You can read more about Go's source file organization here: https://golang.org/doc/code.html