I'm trying to write a basic go program that calls a function on a different file, but a part of the same package. However, it returns:
undefined: NewEmployee
Here is the source code:
main.go:
package main
func main() {
emp := NewEmployee()
}
employee.go:
package main
type Employee struct {
name string
age int
}
func NewEmployee() *Employee {
p := &Employee{}
return p
}
func PrintEmployee (p *Employee) {
return "Hello world!"
}
Please read "How to Write Go Code".
Use go build or go install within the package directory, or supply an import path for the package. Do not use file arguments for build or install.
While you can use file arguments for go run, you should build a package instead, usually with go run ., though you should almost always use go install, or go build.
go run . - the period being "this directory"
go run *.go is a bad idea, because it will break if you have any build constraints or test files.I just had the same problem in GoLand (which is Intellij IDEA for Go) and worked out a solution. You need to change the Run kind from File to Package or Directory. You can choose this from a drop-down if you go into Run/Edit Configurations.
Eg: for package ~/go/src/a_package, use a Package path of a_package and a Directory of ~/go/src/a_package and Run kind of Package or Directory.
Run -> Run... -> Edit Configuration... and you will see the Run kind. For me the Directory solved the issue. The Package gave me other errors, thanks.If you're using go run, do go run *.go. It will automatically find all go files in the current working directory, compile and then run your main function.
go run !(*_test).go -- Golang: run all .go files within current directory through the command line (multi file package)
! to negate the expansion of the glob requires extglob to be set (shopt -s extglob).go run . will run all of your files. The entry point is the function main() which has to be unique to the main package.
Another option is to build the binary with go build and run it.
You can try one of the following:
Method 1:
MyProjectgo build./MyProjectYou can do both steps at once by typing go build && ./MyProject. Go files of the package main are compiled to an executable.
Method 2:
go run *.go. It won't create any executable but it runs.If you want to call a function from another go file and you are using Goland, then find the option 'Edit configuration' from the Run menu and change the run kind from File to Directory. It clears all the errors and allows you to call functions from other go files.
I had a nasty import "C" in one of my go files.
you should use go modules now, if you are not following How to write go code
With go module you don't have to put the code in the $GOPATH/src. it can live in any other location as well.
You can move the code to different directory like /employee, To make it work Just under employee directory initialise the go module
go mod init example.com/employee
I also encountered this problem when using goland.
Need to run as a package
The following two ways can be solved.
I ran into the same issue with Go11, just wanted to share how I did solve it for helping others just in case they run into the same issue.
I had my Go project outside $GOPATH, so I had to turned on GO111MODULE=on without this option turned on, it will give you this issue; even if you you try to build or test the whole package or directory it won't be solved without GO111MODULE=on
While this doesn't directly address the OP's specific issue, I thought I'd chime in with the solution to my "undefined" error: the file with the undefined method had a build constraint (build tag).
More specifically, I accidentally included a build constraint to remove testing files from my deployed application binary in a utility function file used by my deployed binary. So in the OP's example - if employee.go had a build constraints their go build command would need to include a -tags flag matching the constraint in in order to have the file included.
For more info read this blog post: https://dave.cheney.net/tag/build-constraints
Took a while to drill down my own MRE for this, so hopefully it will help others, despite being brief:
This can also occur if your functions / structs are defined in a file that has import "C", which will be silently ignored if CGO_ENABLED=0 is in your go environment, leading to you staring at a two file package that somehow is unable to share between themselves.
In GoLand,
If you right clic a file, it shows you commands to run, debug, test that file.
If you right clic a directory, it will be the same for that "package", expecting a main.go file inside the directory
If your source folder is structured /go/src/blog (assuming the name of your source folder is blog).
That should run all of your files at the same time, instead of you having to list the files manually or "bashing" a method on the command line.
package x, also your main package typically only contains a single file, then imports the other pieces it needsgo run? (and see golang.org/doc/code.html)main.goandemployee.go? Because all go files are supposed to have a package statement, and I don't see any in yours. See: golang.org/doc/code.html#PackageNamesgotool.