Class: Cabin::Context

Inherits:
Object
  • Object
show all
Defined in:
lib/cabin/context.rb

Overview

Logging context exists to make it easy to add and later undo any changes made to the context data associated with a given Logging::Channel

Usage:

context = channel.context
context["foo"] = "Hello world!"
channel.info("Sample log") # output includes { "foo" => "Hello world!" }
context.clear
channel.info("Sample log 2") # context cleared, key "foo" removed.

Essentially, a Cabin::Context acts as a transactional proxy on top of a Cabin::Channel. Any changes you make in a context are passed through to the channel while keeping an ordered record of the changes made so you can unroll those changes when the context is no longer needed..

Instance Method Summary collapse

Constructor Details

#initialize(channel) ⇒ Context

Returns a new instance of Context.



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# File 'lib/cabin/context.rb', line 20

def initialize(channel)
  @changes = []
  @channel = channel
end

Instance Method Details

#[](key) ⇒ Object

def []=



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# File 'lib/cabin/context.rb', line 36

def [](key)
  @channel[key]
end

#[]=(key, value) ⇒ Object

def on_clear



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# File 'lib/cabin/context.rb', line 29

def []=(key, value)
  # Maintain a record of what was changed so clear() can undo this context.
  # This record is in reverse order so it can be undone in reverse later.
  @changes.unshift([key, value, @channel[key]])
  @channel[key] = value
end

#clear ⇒ Object

Undo any changes made to the channel by this context.



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# File 'lib/cabin/context.rb', line 41

def clear
  @changes.each do |key, value, original|
    if original.nil?
      @channel.remove(key)
    else
      @channel[key] = original
    end
  end
end

#on_clear(&block) ⇒ Object

def initialize



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# File 'lib/cabin/context.rb', line 25

def on_clear(&block)
  @clear_callback = block
end