init

.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
+/.crystal-version

.travis.yml

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+language: crystal
+sudo: false
+script:
+  - make test

LICENSE

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+The MIT License (MIT)
+
+Copyright (c) 2018 maiha
+
+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.

Makefile

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+SHELL=/bin/bash
+
+VERSION=
+CURRENT_VERSION=$(shell git tag -l | sort -V | tail -1)
+GUESSED_VERSION=$(shell git tag -l | sort -V | tail -1 | awk 'BEGIN { FS="." } { $$3++; } { printf "%d.%d.%d", $$1, $$2, $$3 }')
+
+.SHELLFLAGS = -o pipefail -c
+
+.PHONY : test
+test: check_version_mismatch spec
+
+.PHONY : spec
+spec:
+	crystal spec -v --fail-fast
+
+.PHONY : check_version_mismatch
+check_version_mismatch: shard.yml README.md
+	diff -w -c <(grep version: README.md) <(grep ^version: shard.yml)
+
+.PHONY : version
+version:
+	@if [ "$(VERSION)" = "" ]; then \
+	  echo "ERROR: specify VERSION as bellow. (current: $(CURRENT_VERSION))";\
+	  echo "  make version VERSION=$(GUESSED_VERSION)";\
+	else \
+	  sed -i -e 's/^version: .*/version: $(VERSION)/' shard.yml ;\
+	  sed -i -e 's/^    version: [0-9]\+\.[0-9]\+\.[0-9]\+/    version: $(VERSION)/' README.md ;\
+	  echo git commit -a -m "'$(COMMIT_MESSAGE)'" ;\
+	  git commit -a -m 'version: $(VERSION)' ;\
+	  git tag "v$(VERSION)" ;\
+	fi
+
+.PHONY : bump
+bump:
+	make version VERSION=$(GUESSED_VERSION) -s

README.md

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+# composite_logger.cr
+
+Logger interface to write to multiple loggers for [Crystal](http://crystal-lang.org/).
+
+```crystal
+logger = CompositeLogger.new(loggers)
+logger.info("hello")
+# => (stdout) "hello"
+# => (a file) "hello"
+```
+
+## Installation
+
+Add this to your application's `shard.yml`:
+
+```yaml
+dependencies:
+  composite_logger:
+    github: maiha/composite_logger.cr
+    version: 0.1.0
+```
+
+## Usage
+
+```crystal
+require "composite_logger"
+```
+
+### logging to both File and STDOUT
+
+```crystal
+loggers = [
+  Logger.new(STDOUT),
+  Logger.new(File.open("app.log")),
+]
+logger = CompositeLogger.new(loggers)
+logger.info("hello")
+```
+
+### in memory logging
+
+`memory:` option provides a handy in-memory logging.
+
+```crystal
+loggers = [Logger.new(STDOUT)]
+logger = CompositeLogger.new(loggers, memory: Logger::ERROR)
+...
+unless logger.memory.to_s.empty?
+  STDERR.puts "Some errors occurred while running program."
+  exit -1
+end
+```
+
+## Contributing
+
+1. Fork it (<https://github.com/maiha/composite_logger.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(https://github.com/maiha) maiha - creator, maintainer

shard.yml

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+name: composite_logger
+version: 0.1.0
+
+authors:
+  - maiha <maiha@wota.jp>
+
+
+license: MIT

spec/composite_logger_spec.cr

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+require "./spec_helper"
+
+private def messages_in(io) : Array(String)
+  ary = io.to_s.chomp.gsub(/^.*? -- : (.*?)$/m){$1}.split(/\n/)
+  (ary == [""]) ? Array(String).new : ary
+end
+
+describe CompositeLogger do
+  it "works with multiple loggers" do
+    debug = IO::Memory.new
+    info  = IO::Memory.new
+    loggers = [
+      Logger.new(debug).tap(&.level = Logger::DEBUG),
+      Logger.new(info).tap(&.level = Logger::INFO),
+    ]
+    logger = CompositeLogger.new(loggers)
+    logger.debug("debug")
+    logger.info("info")
+
+    messages_in(debug).should eq(["debug", "info"])
+    messages_in(info).should eq(["info"])
+  end
+
+  describe "#memory" do
+    it "works as a handy in-memory logger" do
+      loggers = [Logger.new(STDOUT)]
+      logger = CompositeLogger.new(loggers, memory: Logger::ERROR)
+
+      logger.info("info")
+      logger.memory.to_s.empty?.should be_true
+
+      logger.error("error")
+      logger.memory.to_s.empty?.should be_false
+    end
+  end
+end

spec/spec_helper.cr

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+require "spec"
+require "../src/composite_logger"

src/composite_logger.cr

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+require "logger"
+
+class CompositeLogger < Logger
+  include Enumerable(Logger)
+
+  @memory : IO::Memory?
+
+  def initialize(@loggers : Array(Logger), memory : Logger::Severity? = nil)
+    if memory
+      @memory = IO::Memory.new
+      @loggers << Logger.new(@memory).tap(&.level = memory)
+    end
+    super(nil)
+  end
+
+  def memory : IO::Memory
+    @memory || raise "Memory logger is not enabled"
+  end
+
+  delegate each, to: @loggers
+
+  {% for method in %w( level= formatter= ) %}
+    def {{method.id}}(v)
+      each do |logger|
+        logger.{{method.id}}(v)
+      end
+    end
+  {% end %}
+
+  {% for method in %w( close ) %}
+    def {{method.id}}(*args)
+      each do |logger|
+        logger.{{method.id}}(*args)
+      end
+    end
+  {% end %}
+
+  {% for method in %w( debug info warn error fatal ) %}
+    def {{method.id}}(*args, **options)
+      each do |logger|
+        logger.{{method.id}}(*args, **options)
+      end
+    end
+
+    def {{method.id}}(*args, **options)
+      each do |logger|
+        logger.{{method.id}}(*args, **options) do |*yield_args|
+          yield *yield_args
+        end
+      end
+    end
+  {% end %}
+end
+
+class CompositeLogger
+  def self.new(logger : CompositeLogger) : CompositeLogger
+    logger
+  end
+
+  def self.new(logger : Logger) : CompositeLogger
+    CompositeLogger.new([logger])
+  end
+end