sig: Optional Type Assertions for Ruby methods. ![[version]](https://camo.githubusercontent.com/01f7572bf8343e0f76348c97ffa03442dc6e86794e9204ebd2fd75e33bdf7f25/68747470733a2f2f62616467652e667572792e696f2f72622f7369672e737667)
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This gem adds the sig method that allows you to add signatures to Ruby methods. When you call the method, it will verify that the method's arguments/result fit to the previously defined behavior:
# On main object
sig [:to_i, :to_i], Integer,
def sum(a, b)
a.to_i + b.to_i
end
sum(42, false)
# Sig::ArgumentTypeError:
# - Expected false to respond to :to_i
# In modules
class A
sig [Numeric, Numeric], Numeric,
def mul(a, b)
a * b
end
end
A.new.mul(4,"3")
# Sig::ArgumentTypeError:
# - Expected "3" to be a Numeric, but is a String
# Explicitely define signature for singleton_class
class B
sig_self [:reverse],
def self.rev(object)
object.reverse
end
end
B.rev 42
# Sig::ArgumentTypeError:
# - Expected 42 to respond to :reverseThe first argument is an array that defines the behavior of the method arguments, and the second one the behavior of the method result. Don't forget the trailing comma, because the method definition needs to be the last argument to the sig method.
Features & Design Goals
- Provide an intuitive way to define signatures
- Only do argument/result type checks, nothing else
- Use Ruby's inheritance chain, don't redefine methods
- Encourage duck typing
- Should work with keyword arguments
- Only target Ruby 2.1+
This is not static typing. Ruby is a dynamic language:
Nevertheless, nothing is wrong with ensuring specific behaviour of method arguments when you need it.
Is this better than rubype?
The rubype gem achieves similar things like sig (and inspired the creation of sig). It offers a different syntax and differs in feature & implementation details, so in the end, it is a matter of taste, which gem you prefer.
Setup
Add to your Gemfile:
gem 'sig'Usage
See example at top for basic usage.
Supported Behavior Types
You can use the following behavior types in the signature definition:
| Type | Meaning |
|---|---|
| Symbol | Argument must respond to a method with this name |
| Module | Argument must be of this module |
| Array | Argument can be of any type found in the array |
| true | Argument must be truthy |
| false | Argument must be falsy |
| nil | Wildcard for any argument |
Example Signatures
sig [:to_i], Numeric, # takes any object that responds to :to_i as argument, numeric result
sig [Numeric], String, # one numeric argument, string result
sig [Numeric, Numeric], String, # two numeric arguments, string result
sig [:to_s, :to_s], # two arguments that support :to_s, don't care about result
sig nil, String, # don't care about arguments, as long result is string
sig {keyword: Integer} # keyword argument must be an intieger
sig [:to_f, {keyword: String}], # mixing positional and keyword arguments is possible
sig [[Numeric, NilClass]], Float # one argument that must nil or numeric, result must be float
sig [Numeric, nil, Numeric], # first and third argument must be numeric, don't care about type of secondSee source(https://github.com/janlelis/sig/blob/master/lib/sig.rb) or specs(https://github.com/janlelis/sig/blob/master/spec/sig_spec.rb) for more features.
Benchmark (Take with a Grain of Salt)
You can run rake benchmark to run it on your machine.
There is still a lot room for performance improvements. Feel free to suggest some faster implementation to do the type checks (even if it is crazy and not clean, as long it does not add too much "magic", a.k.a does not make debugging harder).
Note: Starting with 0.3.0, rubype uses a C extension, which makes it much faster. The benchmark is still run with rubype 0.2.5, because 0.3.x currently does not work on jruby & rbx.
MRI
ruby version: 2.2.2
ruby engine: ruby
ruby description: ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-linux]
sig version: 1.0.1
rubype version: 0.2.5
contracts version: 0.9
Calculating -------------------------------------
pure 107.628k i/100ms
sig 14.425k i/100ms
rubype 12.715k i/100ms
contracts 7.688k i/100ms
-------------------------------------------------
pure 6.856M (± 0.9%) i/s - 34.333M
sig 192.440k (± 1.5%) i/s - 966.475k
rubype 164.811k (± 0.8%) i/s - 826.475k
contracts 90.089k (± 0.7%) i/s - 453.592k
Comparison:
pure: 6855615.3 i/s
sig: 192439.7 i/s - 35.62x slower
rubype: 164810.5 i/s - 41.60x slower
contracts: 90088.6 i/s - 76.10x slower
JRuby 9000
ruby version: 2.2.2
ruby engine: jruby
ruby description: jruby 9.0.0.0-SNAPSHOT (2.2.2) 2015-05-04 6055b79 Java HotSpot(TM) 64-Bit Server VM 24.80-b11 on 1.7.0_80-b15 +indy +jit [linux-amd64]
sig version: 1.0.1
rubype version: 0.2.5
contracts version: 0.9
Calculating -------------------------------------
pure 70.898k i/100ms
sig 5.308k i/100ms
rubype 3.152k i/100ms
contracts 279.000 i/100ms
-------------------------------------------------
pure 8.848M (±13.7%) i/s - 42.539M
sig 178.169k (±10.3%) i/s - 881.128k
rubype 119.689k (±26.5%) i/s - 444.432k
contracts 56.780k (±16.8%) i/s - 265.887k
Comparison:
pure: 8848039.4 i/s
sig: 178168.8 i/s - 49.66x slower
rubype: 119689.0 i/s - 73.93x slower
contracts: 56780.4 i/s - 155.83x slower
RBX 2.5.3
ruby version: 2.1.0
ruby engine: rbx
ruby description: rubinius 2.5.3.c25 (2.1.0 fbb3f1e4 2015-05-02 3.4 JI) [x86_64-linux-gnu]
sig version: 1.0.1
rubype version: 0.2.5
contracts version: 0.9
Calculating -------------------------------------
pure 114.964k i/100ms
sig 9.654k i/100ms
rubype 3.775k i/100ms
contracts 3.964k i/100ms
-------------------------------------------------
pure 23.585M (± 3.3%) i/s - 117.263M
sig 134.304k (± 3.1%) i/s - 675.780k
rubype 56.042k (± 1.7%) i/s - 283.125k
contracts 69.820k (± 1.8%) i/s - 348.832k
Comparison:
pure: 23585373.7 i/s
sig: 134303.7 i/s - 175.61x slower
contracts: 69819.9 i/s - 337.80x slower
rubype: 56042.1 i/s - 420.85x slower
Deactivate All Signature Checking
require 'sig/none' # instead of require 'sig'Alternatives for Type Checking and More
- https://github.com/gogotanaka/Rubype
- https://github.com/egonSchiele/contracts.ruby
- https://github.com/plum-umd/rtc
MIT License
Copyright (C) 2015 Jan Lelis https://janlelis.com. Released under the MIT license.