Going public. v0.0.1 🚀

- It is pre-release for test and experimentation.

Author: rodrigopinto

.editorconfig

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+root = true
+
+[*.cr]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+indent_style = space
+indent_size = 2
+trim_trailing_whitespace = true

.gitignore

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+/docs/
+/lib/
+/bin/
+/.shards/
+*.dwarf
+
+# Libraries don't need dependency lock
+# Dependencies will be locked in application that uses them
+/shard.lock

.travis.yml

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+language: crystal
+
+script:
+  - crystal spec
+  - crystal tool format --check

CHANGELOG.md

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+### [0.0.1] - 2019-02-21
+
+* Going public! 🚀
+
+[0.0.1]: https://github.com/rodrigopinto/can_use/releases/tag/v0.0.1

LICENSE

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+The MIT License (MIT)
+
+Copyright (c) 2019 Rodrigo Pinto
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

README.md

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+# can_use
+
+🤔 Can I use this feature? Yes, sure!
+
+> CanUse is a minimalist feature toggle/flag for crystal, based on yaml file.
+
+[![GitHub release](https://img.shields.io/github/release/rodrigopinto/can_use.svg)](https://github.com/rodrigopinto/can_use/releases)
+
+[![Build Status](https://travis-ci.org/rodrigopinto/can_use.svg?branch=master)](https://travis-ci.org/rodrigopinto/can_use)
+
+## Installation
+
+1. Add the dependency to your `shard.yml`:
+
+```yaml
+dependencies:
+  can_use:
+    github: rodrigopinto/can_use
+```
+2. Run `shards install`
+
+## Usage
+
+
+1. Require the library on your code base.
+
+	```crystal
+	require "can_use"
+	```
+
+2. Create a file with the features toggle definitions.
+We suggest to name it as `featutes.yaml`, but it is up to you.
+
+	**Note:** The `defaults` block is mandatory, as it will be used as fallback when values are not defined on the environment set on `configuration`. Example:
+
+	```yaml
+	defaults:
+	  new_payment_flow: false
+	  rating_service: false
+
+	development:
+	  new_payment_flow: true
+	  rating_service: false
+
+	your_environment:
+	  new_payment_flow: true
+	```
+
+3. Configure the environment and the path to the yaml.
+
+	```crystal
+	CanUse.configure do |config|
+	  config.file = "path/to/features.yaml"
+	  config.environment = "your_environment"
+	end
+	```
+
+4. Verify if a feature is toggled on/off
+
+	```crystal
+	if CanUse.feature?("new_payment_flow")
+	  # do_something
+	end
+	```
+
+
+## Development
+
+1. Install the dependencies.
+
+	```bash
+	$ shards install
+	```
+
+2. Implement and test your changes.
+
+	```bash
+	$ crystal spec
+	```
+
+
+3. Run fomart tool to verify code style.
+
+	```bash
+	$ crystal tool format
+	```
+
+## TODO
+
+- [ ] Add ability to toggle on/off a feature programatically, ex: `CanUse.enable("feature")`.
+- [ ] Allows ENVIRONMENT variables to set/override a value for a key.
+
+## Contributing
+
+1. Fork it (<https://github.com/rodrigopinto/can_use/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
+
+## Credits
+
+This shard was initially inspired by [can_do][1] (Ruby).
+
+## Contributors
+
+- [Rodrigo Pinto](https://github.com/rodrigopinto) - creator and maintainer
+
+[1]: https://github.com/blacklane/can_do

shard.yml

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+name: can_use
+version: 0.0.1
+
+authors:
+  - Rodrigo Pinto <contato@rodrigopinto.me>
+
+crystal: 0.27.2
+
+license: MIT

spec/can_use_spec.cr

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+require "./spec_helper"
+
+describe CanUse do
+  describe ".configure" do
+    context "when file is not set on the configuration" do
+      it "raises an error" do
+        expect_raises CanUse::Error, "feature_one not found" do
+          CanUse.feature?("feature_one")
+        end
+      end
+    end
+  end
+
+  describe ".feature?" do
+    CanUse.configure do |config|
+      config.file = "spec/fixture/features.yml"
+    end
+
+    it "raises an error when a feature key does not exist" do
+      expect_raises CanUse::Error, "does_not_exist not found" do
+        CanUse.feature?("does_not_exist")
+      end
+    end
+
+    context "accepts a block" do
+      it "evaluates it when feature? returns true" do
+        evaluated = false
+
+        CanUse.feature?("feature_one") do
+          evaluated = true
+        end
+
+        evaluated.should be_true
+      end
+
+      it "does not evaluate it when feature? returns false" do
+        evaluated = false
+
+        CanUse.feature?("feature_two") do
+          evaluated = true
+        end
+
+        evaluated.should be_false
+      end
+    end
+
+    context "with no environment defined" do
+      it "uses the defaults value" do
+        allowed = CanUse.feature?("feature_one")
+        allowed.should be_true
+
+        allowed = CanUse.feature?("feature_two")
+        allowed.should be_false
+      end
+    end
+
+    context "when development environment defined" do
+      Spec.before_each do
+        CanUse.configure do |config|
+          config.environment = "development"
+        end
+      end
+
+      it "uses the defaults value" do
+        allowed = CanUse.feature?("feature_one")
+        allowed.should be_true
+      end
+
+      it "uses development environment if the key exists" do
+        allowed = CanUse.feature?("feature_two")
+        allowed.should be_true
+      end
+    end
+  end
+end

spec/fixture/features.yml

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+defaults:
+  feature_one: true
+  feature_two: false
+development:
+  feature_two: true
+production:
+  feature_one: false

spec/spec_helper.cr

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+require "spec"
+require "../src/can_use"

src/can_use.cr

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+require "yaml"
+
+# CanUse is a minimalist feature toggle for Crystal.
+module CanUse
+  VERSION = "0.1.0"
+
+  @@features = Hash(YAML::Any, YAML::Any).new
+  @@config = Config.new
+
+  # Sets the configuration for `CanUse`
+  #
+  # ### Example
+  #
+  # ```
+  # CanUse.configure do |config|
+  #   config.environment = "development"
+  #   config.file = "config/features.yml"
+  # end
+  # ```
+  def self.configure
+    yield @@config
+    @@features = YAML.parse(File.read(@@config.file)).as_h
+  end
+
+  # Returns `true` or `false` based on the feature configuration.
+  # Otherwise, reads from the default value.
+  #
+  # ### Example
+  #
+  # ```
+  # if CanUse.feature?("feature_one")
+  #   # do_something
+  # end
+  # ```
+  def self.feature?(name : String)
+    features.fetch(name, defaults[name]).raw
+  rescue KeyError
+    raise Error.new("#{name} not found")
+  end
+
+  # Evaluates the block if the feature returns `true`..
+  #
+  # ### Example
+  #
+  # ```
+  # CanUse.feature?("feature_one") do
+  #   puts "Yeah, I cam use!"
+  # end
+  # ```
+  def self.feature?(name : String, &block)
+    return unless feature?(name)
+
+    yield
+  end
+
+  private def self.features : Hash(YAML::Any, YAML::Any)
+    @@features[@@config.environment].as_h
+  end
+
+  private def self.defaults : Hash(YAML::Any, YAML::Any)
+    @@features[Config::DEFAULTS].as_h
+  end
+
+  class Error < Exception; end
+
+  private class Config
+    DEFAULTS = "defaults"
+
+    property file : String = ""
+    property environment = DEFAULTS
+  end
+end