GNU/Emacs mode that setup local Go playground for code snippets like play.golang.org or even better :)

Last update: Dec 15, 2022

Comments: 10

Local Golang playground

The simple mode for GNU/Emacs for setting up local Go language playground with features similar (and with help of go-mode even outperform!) service at play.golang.org. You may treat it like the simple REPL for Go. This is not a wrapper for working with play.golang.org from Emacs (it is already did by original go-mode), this is complete alternative for setting local playground inside Emacs without using browser for experiments with code snippets.

Web playground at play.golang.org is a nice idea. It has not require setup and it executes your code in a restricted environment where you can't damage you system. But it brings many restrictions too especially when you want use additional helpers for working with your code: formatters, code completers etc. Emacs offers many such tools for Go development so it is the most comfortable play with snippets inside Emacs instead of rude webeditor. Of course local playground requres you to setup Go environment but if you developing in Go (or you want to do it) you are anyway would need to setup go-mode and helper tools for working with code in a comfortable way.

Features

it works under go-mode with all you plugins installed (like autocompletion, linters and so on)
the playground files saved in the subdirectory under GOPATH that helps you keep library of useful snippets
it could split the code into arbitrary number of files
it could import any external packages from your GOPATH
uses vendored packages in your snippet dir
could be used with modules with the latest Go versions

Install

Firstly install go-mode and gotest — these are mandatory. Setup any additional tools you want for Golang (see Emacs Wiki for guides or google for "emacs+golang"). Personally I recommend use goimports for automatically add import clauses to your snippets. Because usually when you test some ideas you want get working code as fast as possible. And goimports helps with it.

Install go-playground from MELPA:

M-x package-install RET go-playground

If you want share snippets use go-play-buffer from go-mode. Install gist-buffer from MELPA if you want publish gists on github.com.

The mirror repository of the project: https://notabug.org/grafov/go-playground. I really not think that this small project need the mirror but I just would like advertise a nice git hosting for FOSS. Try notabug.org for your projects! :)

Usage

Quick start

From any mode run M-x go-playground for start a new playground buffer filled with basic template for main package (see the picture below).
Add your code then press Ctl-Return (it bound to go-playground-exec command). It will save, compile and exec the snippet code.
When you played enough with this snippet just run M-x go-playground-rm. It will remove the current snippet with its directory and all files.

Mode not offers default bindings except Ctl-Return. It just lefts the space for you.

For easy running the template declares main package with defined main() function. Each snippet saved to its own directory (named by timestamp by default). Remember go-playground runs the compiler as go run *.go so any sources from the snippet directory will be included.

List of interactive functions

Function name	Description
`go-playground`	Create a new playground buffer with basic template for the `main` package.
`go-playground-download`	Download the snippet from the URL at play.golang.org.
`go-playground-exec`	Save, compile and run the code of the snippet.
`go-playground-cmd`	Save the code then prompts for the command (compile-mode used).
`go-playground-upload`	Upload the buffer to play.golang.org and return the short URL.
`go-playground-rm`	Remove the snippet with its directory with all files.

List of customizable variables

Function name	Description
`go-playground-ask-filename`	Ask for the snippet filename on a new playground creation. By default it got name `snippet.go`.
`go-playground-basedir`	Default directory where snippets dirs will placed. Each new snippet got a new dir under this. It has sense place the default directory under GOPATH. Var introduced in the release 1.1.
`go-playground-confirm-deletion`	Ask for confirmation before snippet deletion. It may be annoying so you can switch confirmations off. Var introduced in the release 1.2.
`go-playground-go-command`	Set a custom path to go command, possibly with environment (example: "CGO_ENABLED=0 /opt/bin/go").
`go-playground-init-command`	Setup shell command that will be run once when a new snippet just created.
`go-playground-compiler-args`	That arguments should be passed for the compiler.

Example screen after creation of a new snippet:

Using with go modules

By default the playground runs go-command as it defined in settings of go-mode. You could use special customized compiler path with go-playground-go-command. For using with modules it could be used such way:

Set go-playground-go-command to "GO111MODULE=on".
Set go-playground-init-command to "go mod init".

Similar projects

Try go-scratch it even simplier than go-playground. But it prevents you from using many of tools because it not keeps code in files.
gorepl-mode is REPL for Go, helpful for interactive research of code.

Licence

Under terms of GPL v3. See LICENSE file.

Future plans and accepting contributions

I don't want to make this package much complex. Most of go-playground functions depends on other packages around go-mode. And it is good way. But one thing I want to add is snippet list buffer where you can easily find and edit/delete snippets of your library. Bugfixes and small features accepted as well.

Owner

Alexander I.Grafov

I am high skilled master of useless code with a specialization on the architecture of perpetuum mobile engines and cloud castles. I code just because I can.

https://github.com/grafov/go-playground

Comments

Please delete only playground files...

Here is what just happened:

I called go-playground-rm when I'm working on an regular file accidentally(it's the last command I just run), and the whole directory containing this file was deleted, without confirmation...
playground-exec doesn't work under windows.

windows CMD doesn't automatically expand *, and go run doesn't either, so M-x compile go run *.go doesn't work, giving this error

CreateFile *.go: The filename, directory name, or volume label syntax is incorrect.

which is the same as running go run *.go under CMD or Powershell. Though saving the file and then running M-x eshell go run *.go works fine, of course, as a stopgap work around.

I suspect *.go needs to get expanded before being passed to M-x compile, or some other method used to run the playground.
Fix a bug where starting a playground would change current directory

When starting a new playground, before executing the playground initialistaion command, the current directory would be changed to the snippet directory. This would have the side-effect of setting the current directory of whatever buffer the user was in previously, which could cause unexpected behaviour with other commands.

Instead of changing directory, locally bind default-directory so that the initialisation command will be executed from the snippet directory without an side effects.
add autoload to minor mode definition

It can be useful for open old snippets from previous sessions. For now if I try to open snippet from previous sessions I see message Ignoring unknown mode ‘go-playground-mode’
Prompt for git passphrase
This is probably an issue with my environment rather than a bug with go-playground, but I was wondering if you had any insights on this:

-*- mode: compilation; default-directory: "~/.go/src/playground/at-2019-06-13-150529/" -*- Compilation started at Thu Jun 13 15:15:09 go run *.go Enter passphrase for key '/home/user/.ssh/github':

In the snippet, I'm importing a package that's not in the standard library.

If I run the snippet in a shell with go run the snippet compiles and runs correctly. There's no request for the github key.

I'm on go1.12.5 linux/amd64 and GNU Emacs 26.2 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.8) of 2019-04-12.

By the way -- thanks for making this -- I use it almost every day.
fix: go-playground-upload not working in playground snippet buffers

This fixes the condition in the go-playground-upload function, so it runs go-play-buffer within go-playground snippet file buffers only. Previously it would run it in any buffer, except snippet buffers.

I also removed the cursor movement and insertion of the result from go-play-upload, as default behavior of go-play-buffer and go-play-region is to place the URL on the killring, and can be customized setting the go-play-browse-function variable.

Multi-file support

Go playground has a multi-file support, like https://play.golang.org/p/rq4J90MxTKJ

package main

import (
	"play.ground/foo"
)

func main() {
	foo.Bar()
}

-- go.mod --
module play.ground

-- foo/foo.go --
package foo

import "fmt"

func Bar() {
	fmt.Println("This function lives in an another file!")
}

Is there any way to execute similar snippet in go-playground?

Improve snippet template comment

Just print commands for snippet removing and uploading as elisp commands in braces. So you could move to end of command and press C-x-e for fastly execute the command without key binding. Usability rules! :)
Update go-playground.el

go-playground-init-command doesn't work for me, because go mod init needs a package namespace base (i.e: github.com/grafov/) and the current package name.

Added a template variable to go-playground-init-command to achieve this, so for example you could then do :

(setq go-playground-init-command "go mod init github.com/grafov/%file-sans")

and %file-sans would expand to the local filename sans extension....

imported those function from the multi-compile package https://github.com/ffevotte/multi-compile since well it was already there so may as well use them.
Add command for reusing the latest snippet
Store the path to the latest created snippet to the variable

Add command go-playground-latest that would open that snippet instead of creating a new one

Maybe also track the paths for the N latest created snippets and offer the way to reuse them.

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GNU/Emacs mode that setup local Go playground for code snippets like play.golang.org or even better :)

Local Golang playground

Features

Install

Usage

Quick start

List of interactive functions

List of customizable variables

Using with go modules

Similar projects

Licence

Future plans and accepting contributions

Owner

Alexander I.Grafov

Comments

Please delete only playground files...

playground-exec doesn't work under windows.

Fix a bug where starting a playground would change current directory

add autoload to minor mode definition

Prompt for git passphrase

fix: go-playground-upload not working in playground snippet buffers

Multi-file support

Improve snippet template comment

Update go-playground.el

Add command for reusing the latest snippet

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