I'm writing my first Go code which among other things, sends an email. After finding out that the package net/smtp only supports Plain Auth (but some providers like outlook doesn't support it), I asked for a solution and got pointed out to https://gist.github.com/andelf/5118732.
That code works like a charm, but as it's not something written by myself, I would like to add it in a separate file and just reference it in my main.go.
What's the right approach to have multiple files in the same package? I don't want to create a different package just for that code, first because it's not mine, and secondly, because I think it's an "overkill" approach, isn't it?
I thought that as long as the files are in the same directory, I could have many *.go files, but it seems it's not working out. If I just create a file with the content of that gist, the compiler fails because expected package, found import. If I add something like package auth, then it fails because found packages auth (auth.go) and main (main.go)
So, what's the general practice in this situations? Just create packages for everything?
You can have only one package in a directory, and it looks like you don't need a package for this addition, so you can simply put that in a separate file, and add package main at the top. Having a main package and putting everything under it works up to a point. As things get larger, you have to break it up into self-contained packages.
If your current working directory is in GOPATH, then you can just add new go file with same package name main.
If your current working directory is not in GOPATH, you can still put them in multiple go files and when you run the program, you should use go run *.go instead of just go run main.go.
There are also other options which you can refer Run code with multiple files in the same main package in GoLang for detail.
Related
I have the following situation, where I can't use romanNumerals in romanserver, inside a folder in my module directory.
go run romanserver/main.go
romanserver/main.go:13:2: no required module provides package github.com/BuddhiLW/roman/romanNumerals; to add it:
go get github.com/BuddhiLW/roman/romanNumerals
I want to upload the roman project to GitHub containing both romanNumerals and romanserver. Of course, I would like to export variables from one another.
I'm still confused about how that is done in Go.
EDIT: I deleted go.mod in both romanNumerals and romanserver, and now everything is working, just like
Cerise Limón pointed out.
I am building a web application in Go and as part of it I have several middelware functions defined. Right now they all live in "my/middleware" package. That namespace is becoming very cluttered by all the different functions I've defined so I decided to put them all in their own subdirectories, e.g. "my/middleware/gzip". When I do this I get the error:
no buildable Go source files my/middleware
I don't want all of these functions in the same namespace, but it seems my only option is to create a placeholder .go file in the my/middleware directory with an empty init function or something. That sounds terrible so I'd like suggestions on how to achieve my goal to group a similar class of packages when there isn't any shared/common code to live in the parent package.
You are actually taking the right decision by splitting the files into different subfolders. It is not different than what is done here
https://golang.org/pkg/compress/
This allows for the clients of your framework to take only what they need. The idea is to avoid dependency bloating. Go is all about being lean.
The error you receive is because you try to build a package that doesn't exist. Think of that folder as a logical grouping mechanism, you need to build the packages given by the child folders individually.
I'm playing with golang and made a tool for password generation. Initially it was intended to be used as a command line tool. I later separated the generation logic into a separate package (still same github repository) and left the main function in the root of the project. Now I also want to add a simple web frontend (nothing fancy), but I don't know how to structure the packages.
Am I supposed to put both the command line entry point as well as the web UI into their own packages in the same project (which leaves the root empty). Or maybe I should move the actual generation library to the root and the UIs in separate packages. I guess the other option is to have the UIs in separate projects on github, but they are only going to be used for this library, so it does not seem like a good idea.
I remember seeing in some projects packages named cmd for example, but never have I encountered one, with multiple front ends. Is there a go(-gettable-)way for doing this?
I agree that there's not much point in making separate projects/repositories if they're only going to be used for this library. I would just have a cmd directory with a subdirectory for each executable you're building.
Something like this:
github.com/user/project
generation
cmd
cmdline
main.go
web
main.go
The main.go files can use the functionality that you've broken out into your "generation" package.
The name of the executables produced by go build will be the name of the parent directory, so cmdline and web in this example (you would want to choose better names).
Note: you don't actually have a package cmdline or web. The files in those directories would all be in [their own separate] package main.
I'm developing a small tool with Go. And recently, I noticed that the tool needs to be invoked from a shell script, because it's using shell function.
Assume my tool is called atool. So, go build generates a binary atool, and my tool has a Go structure as github.com/myaccount/atool. Now, i want to build atool-cli binary with go build, and invoke it from shell script atool. How can I achieve this?
The only way coming in my mind is change go structure as github.com/myaccuont/atool-cli. But I don't want to do this because the already announced, and also, the path seems a bit funny name.
Just to make my comment "official":
go build -o atool-cli github.com/you/atool
One way packages structure themselves as a library, and provide main packages is to put their main entrypoints in subdirectories.
You can have a main package in github.com/myaccount/atool/atool-cli, which imports github.com/myaccount/atool and implements func main(). Some packages with multiple commands even have a /cmd/ directory with multiple cli tools that can be built (see camlistore as an example)
I would like to use signatures for a program that I am writing in Go, but I can't figure out the documentation, which is here. In particular, I would like to use the SignPKCS1v15 and VerifyPKCS1v15 functions, but I'm not sure exactly what I have to pass as arguments. I would greatly benefit from some example code of these two functions. Thanks.
Note: The message that I would like to send is a struct that I defined.
I think the src\pkg\crypto\rsa\pkcs1v15_test.go file in the Go source tree should be a good start.
An update striving provide more context… Go source contains many tests for the code in its standard library (and the crypto/rsa package is a part of it), so whenever you have no idea how to use a standard package (or, actually, any other Go package), a good place to start is to look at the tests involving that package as testing code naturally uses the package! Tests are kept in files ending in _test.go, usually have meaningful names and are located in the same directories actual code implementing a particular package is kept.
So in your particular case you could do this:
Download the Go source package of the version matching your compiler (what go version shows) and unpack it somewhere.
Navigate to the directory matching the package of interest. Code for standard Go packages is located in the "pkg" directory under the "src" top-level directory, so if you're interested in the crypto/rsa package, you need the src/pkg/crypto/rsa directory.