Lap

Don't write your code, and rbs types! Write the rbs types first, then generate a template to fill in with business logic.

A lapidary (or lapidist) is someone who cuts, polishes, or engraves precious stones.

Usage

$ lap sig/file.rbs # outputs to stdout
$ lap sig/file.rbs > lib/file.rb # output into a file

Example

0. Plan your project/module/class by writing some blueprints:

# sig/lib/bank/account.rbsmoduleBankclassAccountattr_readerinterest_rate: Floatattr_readerowner: Bank::Customerattr_readerbalance: Floatdefinitialize: (Bank::Customerowner,Floatinterest_rate, ?Floatbalance) -> voidtypedate_or_dt=Date | DateTime# can optionally specify when the transaction should take placedefdeposit: (Floatamount, ?when: date_or_dt) -> Float# can optionally specify when the transaction should take placedefwithdraw: (Floatamount, ?when: date_or_dt) -> Float# must filter results by specifying `to` and `from` paramsdeftransactions: (from: date_or_dt,to: date_or_dt)->Array[Bank::Transaction]endend

1. Generate your ruby templates

$ lap sig/lib/bank/account.rbs > lib/bank/account.rb

(Generates lib/bank/account.rb)

moduleBankclassAccountattr_reader:interest_rateattr_reader:ownerattr_reader:balancedefinitialize(owner,interest_rate,balance=nil)# returns voidend# can optionally specify when the transaction should take placedefdeposit(amount,when: nil)# TODO: return Floatend# can optionally specify when the transaction should take placedefwithdraw(amount,when: nil)# TODO: return Floatend# must filter results by specifying `to` and `from` paramsdeftransactions(to:,from:)# TODO: return Arrayendendend

2. Fill in your business logic!

moduleBankclassAccountattr_reader:interest_rateattr_reader:ownerattr_reader:balancedefinitialize(owner,interest_rate,balance=0)@owner=owner@interest_rate=interest_rate@balance=balanceend# can optionally specify when the transaction should take placedefdeposit(amount,when: nil)@balance += amountend# can optionally specify when the transaction should take placedefwithdraw(amount,when: nil)@balance -= amountend# must filter results by specifying `to` and `from` paramsdeftransactions(to:,from:)Transaction.where("created_at BETWEEN ? AND ?",from,to)endendend

From here, you now have some ruby code which you can type check!

Experimental:

There is an experimental feature which allows you to specify some ruby logic within your rbs files for your methods. You specify it between @!begin and @!end, eg.:

# take some moeny out of the customers account# @!begin# @balance -= amount# @!enddefwithdraw(Floatamount)->Float

This would produce:

# take some moeny out of the customers accountdefwithdraw(amount)@balance -= amountend

Installation

Add this line to your application's Gemfile:

gem'lap'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install lap

Configuration

You can specify preferences in a .lap.yml file in your project directory. Example

indent: 4# default is 2frozen_string_literals: false # add 'frozen_string_literal: true' to top of file; default is true# preferred line length in characters; default is 100. Note "preferred" - not always a guaranteepreferred_line_length: 80

Coverage

Currently not every feature of RBS is supported - yet! (contributions welcome!)

Feature	Coverage
classes (includes nested)	✅
modules (includes nested)	✅
class methods	✅
instance methods	✅
required positional arguments	✅
optional positional arguments	✅
required keyword arguments	✅
optional keyword arguments	✅
method comments	✅
access modifiers	✅
attr_reader	✅
attr_writer	✅
attr_accessor	✅
include	✅
extend	✅
methods with blocks	✅
method overloading	⚠️
procs	⚠️
constants	⚠️
interfaces	⚠️

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/johansenja/lap.

License

The gem is available as open source under the terms of the MIT License.