Class: MetaEvents::Definition::Version

Inherits:
Object
  • Object
show all
Defined in:
lib/meta_events/definition/version.rb

Overview

A Version is the common top level of hierarchy in the MetaEvents DSL. A Version represents a version of your application's entire event hierarchy – that is, you should create a new Version if (and only if) you decide to rearrange major parts of, or all of, your event hierarchy. (This is something that, in my experience, happens more often than you'd imagine. ;)

A Version belongs to a DefinitionSet; it has a number, which is just an integer (that you'll probably be happier with if you make sequential, but no such requirement is imposed), the date (and possibly time) that it was introduced (for record-keeping purposes). Additionally, you can mark a version as retired, which means that it is still accessible for record-keeping purposes but will not allow any of its events to actually be fired.

Constant Summary collapse

DEFAULT_PROPERTY_SEPARATOR =
"_"

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(definition_set, number, introduced, options = { }, &block) ⇒ Version

Creates a new instance. definition_set is the MetaEvents::Definition::DefinitionSet to which this Version belongs; number is an integer telling you, well, which version this is – it must be unique within the DefinitionSet. introduced is a String that must be parseable using Time.parse; this should be the date (and time, if you really want to be precise) that the Version was first used, for record-keeping purposes.

Currently, options can contain:

:retired_at

If present, must be a String representing a date and/or time (as parseable by Time.parse); its presence indicates that this version is retired, meaning that you will not be allowed to fire events from this version. (The date and time itself is present for record-keeping purposes.) Set this if (and only if) this version should no longer be in use, presumably because it has been superseded by another version.

Note that neither the introduction time nor retired-at time are actually compared with Time.now in any way; the introduction time is not used in the event mechanism at all, and the retired_at time is treated as a simple boolean flag (if present, you can't fire events from this version).

The block passed to this constructor is evaluated in the context of this object; this is how we build our DSL.

Raises:

  • (ArgumentError)

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# File 'lib/meta_events/definition/version.rb', line 39

def initialize(definition_set, number, introduced, options = { }, &block)
  raise ArgumentError, "You must pass a DefinitionSet, not #{definition_set.inspect}" unless definition_set.kind_of?(::MetaEvents::Definition::DefinitionSet)
  raise ArgumentError, "You must pass a version, not #{number.inspect}" unless number.kind_of?(Integer)

  @definition_set = definition_set
  @number = number
  @introduced = Time.parse(introduced)
  @categories = { }

  options.assert_valid_keys(:retired_at, :property_separator)

  @retired_at = Time.parse(options[:retired_at]) if options[:retired_at]
  @property_separator = options[:property_separator] || DEFAULT_PROPERTY_SEPARATOR

  instance_eval(&block) if block
end

Instance Attribute Details

#definition_setObject (readonly)

Returns the value of attribute definition_set


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# File 'lib/meta_events/definition/version.rb', line 16

def definition_set
  @definition_set
end

#introducedObject (readonly)

Returns the value of attribute introduced


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# File 'lib/meta_events/definition/version.rb', line 16

def introduced
  @introduced
end

#numberObject (readonly)

Returns the value of attribute number


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# File 'lib/meta_events/definition/version.rb', line 16

def number
  @number
end

Instance Method Details

#category(name, options = { }, &block) ⇒ Object

Declares a category within this version; this is part of our DSL. See the constructor of ::MetaEvents::Definition::Category for more information about the arguments.

Raises:

  • (ArgumentError)

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# File 'lib/meta_events/definition/version.rb', line 63

def category(name, options = { }, &block)
  category = ::MetaEvents::Definition::Category.new(self, name, options, &block)
  raise ArgumentError, "There is already a category named #{name.inspect}" if @categories[category.name]
  @categories[category.name] = category
end

#category_named(name) ⇒ Object

Returns the Category with the given name, or raises ArgumentError if there is no such category.


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# File 'lib/meta_events/definition/version.rb', line 70

def category_named(name)
  name = ::MetaEvents::Definition::Category.normalize_name(name)
  @categories[name] || raise(ArgumentError, "#{self} has no category #{name.inspect}; it has: #{@categories.keys.sort_by(&:to_s).inspect}")
end

#fetch_event(category_name, event_name) ⇒ Object

Returns the ::MetaEvents::Definition::Event object for the given category and event name, or raises ArgumentError if no such category or event exists.


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# File 'lib/meta_events/definition/version.rb', line 77

def fetch_event(category_name, event_name)
  category_named(category_name).event_named(event_name)
end

#prefixObject

Returns the prefix that all events in this version should have – something like “pz1”, for example.


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# File 'lib/meta_events/definition/version.rb', line 57

def prefix
  "#{definition_set.global_events_prefix}#{number}_"
end

#property_separatorObject

Returns the string that should be used in property expansion to separate the two (or more) parts of the property name. For example, if you pass to MetaEvents::Tracker#event! in additional_properties (or in the implicit properties taken by MetaEvents::Tracker#initialize) data that looks like :user => { :first_name => 'Fiona', :last_name => 'Darling' }, then, by default, you end up with properties named user_first_name and user_last_name.

If, instead, you set :property_separator => '~' on your Version, then you end up with properties named user~first_name and user~last_name. This can be used to change property names to your liking.

This is defined on the Version so that you can change it if you redo your entire events system. It is not defined at a lower level, because having property names change is a _big deal_ – it breaks data analysis in an analytics system, and so you generally should not change it unless you're changing lots of other stuff that would break analytics as well, like when defining an entire new Version.


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# File 'lib/meta_events/definition/version.rb', line 99

def property_separator
  @property_separator
end

#retired_atObject

Returns the Time at which this version was retired, or nil if it is still active.


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# File 'lib/meta_events/definition/version.rb', line 82

def retired_at
  @retired_at
end

#to_sObject

Override #to_s, for a cleaner view.


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# File 'lib/meta_events/definition/version.rb', line 104

def to_s
  "<Version #{number}>"
end