Emacs Solidity Mode

A simple language mode for the Solidity language. It is a constant work in progress as the language itself also progresses. For information about Solidity check the Tutorial and the Features wiki pages.

Installation

You can simply load the file in your emacs but the recommended way to install it is either via el-get or MELPA.

El-get

If you don’t know how to use el-get you can find more information on its webpage. First install el-get and then (in emacs), press Alt+x (this is in emacs notation written as M-x ) and then type el-get-install. This will prompt you for a package, type solidity-mode and hit enter, this should install all you need.

Melpa

You can also obtain solidity-mode from Melpa as can be seen here.

1. Install melpa and make sure emacs is started with it.
2. Press Alt+x (this is in emacs notation written as M-x ) and then type package-refresh-contents.
3. Press Alt+x and then type package-install. This will prompt you for a package.
4. type solidity-mode and hit enter, this should install all you need.

Configuration

By default solidity-mode associates itself with any files ending in .sol.

If using el-get then you should have a specific package initializing lisp file. If not then you can put these anywhere in your init.el.

Generic configuration

Regardless of where you installed solidity mode from, you need to require the package:

(require 'solidity-mode)

(append that line to your ~/.emacs file)

You can also set the way the comments are inserted by emacs with commands like comment-region. The default is /* .. */ and you can turn it to using // instead by putting the following into your emacs config:

(setq solidity-comment-style 'slash)
;; or
(setq solidity-comment-style 'star) ;; this is the default

Keymap

You can modify the default keybindings of the solidity mode keymap by adding a new key combination for each command you want to change. For example

(define-key solidity-mode-map (kbd "C-c C-g") 'solidity-estimate-gas-at-point)

Interface with linters

Provide path to solc binary

The solc binary is assumed to be part of the PATH. Wherever that is not the case you would have to manually set the location of the binary like below:

(setq solidity-solc-path "/home/lefteris/ew/cpp-ethereum/build/solc/solc")

Note: This better be set before requiring solidity mode.

Provide path to solium binary

The solium binary is assumed to be part of the user’s PATH. If this is not the case then set its location like below:

(setq solidity-solium-path "/home/lefteris/.npm-global/bin/solium")

[Optional] Flycheck interface

Solidity mode can also interface with flycheck if you have it. Make sure to download and install the flycheck package. Then configure it to either work on all modes or enable it only for solidity mode.

Flycheck can interface with solc and/or with solium. We only support integration with solium >= v0.2.0

You have to specifically set the path to both executables and activate the checker integration by setting the following:

To activate flycheck you need the solidity-flycheck package and to add this in your emacs file:

(require 'solidity-flycheck)

To activate solc checker

(setq solidity-flycheck-solc-checker-active t)

To activate solium checker

(setq solidity-flycheck-solium-checker-active t)

Keep in mind that you need to provide the path to either solc or solium unless emacs can already find it in your environment’s PATH. Even if you can call it from the command line it does not mean that EMACS can see it as emacs may be started by systemd at which point PATH is not fully populated.

Configuring solc checker

You can configure flycheck’s solc invocation with the following arguments

std contracts

By default this is false. If you want to include the standard contracts just add the following to your emacs init file

(setq flycheck-solidity-solc-addstd-contracts t)

Configuring solium checker

You can configure flycheck’s solium incocation with the following arguments

solium RC file

By default solium looks at the current directory of the file you are editing in order to find .soliumrc.json. Having this file is required. But you can point to an external configuration file by putting the following anywhere in your emacs init file.

(setq flycheck-solidity-solium-soliumrcfile "/home/path/to/common/.soliumrc.json")

Chaining both checkers

If you enable both checkers then their results are chained. The variable solidity-flycheck-chaining-error-level controls how they are chained. Its value can be either t, error, warning or info and that controls the maximum error level of the solc checker after which solium will not run. If t is given solium will always run. The default is warning, so if anything over than a warning is found in solc solium will not run.

[Optional] Autocompletion

To achieve solidity autcompletion you will need the company-solidity package, a simple company-mode back-end for Solidity. To use it make sure that company-mode is installed and then:

(require 'company-solidity)

What it does

Give completion suggestions for Solidity keywords, global variables, and address methods.

What it isn’t

Smart. The completion suggestions are not context dependent.

Something to watch out for

company-mode treats . as the end of a word, and will cut off compeletion suggestions when you type a .. So, when you’ve typed msg you will get msg.sender, msg.value etc. as completion suggestions. However, as soon as you type msg., the suggestions will disappear.

Local Variables

If you want autocomplete suggestions to include local variables, in addition to Solidity keywords, add the following to your init.el:

(add-hook 'solidity-mode-hook
	(lambda ()
	(set (make-local-variable 'company-backends)
		(append '((company-solidity company-capf company-dabbrev-code))
			company-backends))))

Commands

Gas estimate of function under point

You can get an estimate of the function under the cursor, by placing the curson on top of the function name and typing C-c C-g.

This will call solidity-estimate-gas-at-point and provide a max gas estimate, if possible, for the function.

Features

• Syntax highlighting
• Autocompletion
• Indentation
• On the fly syntax checking with flycheck
• Gas estimation for function under point