`Object.var` macro for Crystal
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README.md

var.cr Build Status

var provides a macro that gives a lazy evaluation to the property variable. Users are freed from ugly not_nil! and tired not initialized constraints and can write simple code.

  • crystal: 0.26.1

Usage

require "var"

class Sample
  var foo = true
  var bar : Int32 = build_bar
  var baz : String
  var counts = Hash(String, Int32).new

  private def build_bar
    1
  end
end

obj = Sample.new
obj.foo?      # => true
obj.foo       # => true
obj.bar?      # => 1
obj.bar       # => 1
obj.baz?      # => nil
obj.baz       # raises "var `baz` is not set yet." (Var::NotReady)
obj.baz = "a"
obj.baz       # => "a"

obj.baz = nil # `nil` assignments are always ignored
obj.baz       # => "a"

obj.counts["a"] = 1
obj.counts    # => {"a" => 1}

Installation

Add this to your application's shard.yml:

dependencies:
  var:
    github: maiha/var.cr
    version: 1.2.0

Development

make test

Contributing

  1. Fork it ( https://github.com/maiha/var.cr/fork )
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request

Contributors

  • maiha maiha - creator, maintainer