class Rake::Task - rake: Ruby Standard Library Documentation

# class Rake::Task

A `Task` is the basic unit of work in a Rakefile. Tasks have associated actions (possibly more than one) and a list of prerequisites. When invoked, a task will first ensure that all of its prerequisites have an opportunity to run and then it will execute its own actions.

Tasks are not usually created directly using the new method, but rather use the `file` and `task` convenience methods.

### Attributes

actions[R]

List of actions attached to a task.

already_invoked[R]

Has this task already been invoked? Already invoked tasks will be skipped unless you reenable them.

application[RW]

`Application` owning this task.

locations[R]

File/Line locations of each of the task definitions for this task (only valid if the task was defined with the detect location option set).

order_only_prerequisites[R]

List of order only prerequisites for a task.

prereqs[R]

List of prerequisites for a task.

prerequisites[R]

List of prerequisites for a task.

scope[R]

Array of nested namespaces names used for task lookup by this task.

sources[W]

List of sources for task.

### Public Class Methods

[](task_name) click to toggle source

Return a task with the given name. If the task is not currently known, try to synthesize one from the defined rules. If no rules are found, but an existing file matches the task name, assume it is a file task with no dependencies or actions.

    # File rake-13.2.1/lib/rake/task.rb, line 404
    def [](task_name)
      Rake.application[task_name]
    end

clear() click to toggle source

Clear the task list. This cause rake to immediately forget all the tasks that have been assigned. (Normally used in the unit tests.)

    # File rake-13.2.1/lib/rake/task.rb, line 391
    def clear
      Rake.application.clear
    end

create_rule(*args, &block) click to toggle source

Define a rule for synthesizing tasks.

    # File rake-13.2.1/lib/rake/task.rb, line 421
    def create_rule(*args, &block)
      Rake.application.create_rule(*args, &block)
    end

define_task(*args, &block) click to toggle source

Define a task given `args` and an option block. If a rule with the given name already exists, the prerequisites and actions are added to the existing task. Returns the defined task.

    # File rake-13.2.1/lib/rake/task.rb, line 416
    def define_task(*args, &block)
      Rake.application.define_task(self, *args, &block)
    end

format_deps(deps) click to toggle source

Format dependencies parameter to pass to task.

    # File rake-13.2.1/lib/rake/task.rb, line 373
    def self.format_deps(deps)
      deps = [deps] unless deps.respond_to?(:to_ary)
      deps.map { |d| Rake.from_pathname(d).to_s }
    end

new(task_name, app) click to toggle source

Create a task named `task_name` with no actions or prerequisites. Use `enhance` to add actions and prerequisites.

    # File rake-13.2.1/lib/rake/task.rb, line 99
    def initialize(task_name, app)
      @name            = task_name.to_s
      @prerequisites   = []
      @actions         = []
      @already_invoked = false
      @comments        = []
      @lock            = Monitor.new
      @application     = app
      @scope           = app.current_scope
      @arg_names       = nil
      @locations       = []
      @invocation_exception = nil
      @order_only_prerequisites = []
    end

scope_name(scope, task_name) click to toggle source

Apply the scope to the task name according to the rules for this kind of task. Generic tasks will accept the scope as part of the name.

    # File rake-13.2.1/lib/rake/task.rb, line 428
    def scope_name(scope, task_name)
      scope.path_with_task_name(task_name)
    end

task_defined?(task_name) click to toggle source

TRUE if the task name is already defined.

    # File rake-13.2.1/lib/rake/task.rb, line 409
    def task_defined?(task_name)
      Rake.application.lookup(task_name) != nil
    end

tasks() click to toggle source

List of all defined tasks.

    # File rake-13.2.1/lib/rake/task.rb, line 396
    def tasks
      Rake.application.tasks
    end

### Public Instance Methods

add_description(description) click to toggle source

Add a description to the task. The description can consist of an option argument list (enclosed brackets) and an optional comment.

    # File rake-13.2.1/lib/rake/task.rb, line 298
    def add_description(description)
      return unless description
      comment = description.strip
      add_comment(comment) if comment && !comment.empty?
    end

all_prerequisite_tasks() click to toggle source

List of all unique prerequisite tasks including prerequisite tasks’ prerequisites. Includes self when cyclic dependencies are found.

    # File rake-13.2.1/lib/rake/task.rb, line 77
    def all_prerequisite_tasks
      seen = {}
      collect_prerequisites(seen)
      seen.values
    end

arg_names() click to toggle source

Name of arguments for this task.

    # File rake-13.2.1/lib/rake/task.rb, line 141
    def arg_names
      @arg_names || []
    end

clear() click to toggle source

Clear the existing prerequisites, actions, comments, and arguments of a rake task.

    # File rake-13.2.1/lib/rake/task.rb, line 153
    def clear
      clear_prerequisites
      clear_actions
      clear_comments
      clear_args
      self
    end

clear_actions() click to toggle source

Clear the existing actions on a rake task.

    # File rake-13.2.1/lib/rake/task.rb, line 168
    def clear_actions
      actions.clear
      self
    end

clear_args() click to toggle source

Clear the existing arguments on a rake task.

    # File rake-13.2.1/lib/rake/task.rb, line 180
    def clear_args
      @arg_names = nil
      self
    end

clear_comments() click to toggle source

Clear the existing comments on a rake task.

    # File rake-13.2.1/lib/rake/task.rb, line 174
    def clear_comments
      @comments = []
      self
    end

clear_prerequisites() click to toggle source

Clear the existing prerequisites of a rake task.

    # File rake-13.2.1/lib/rake/task.rb, line 162
    def clear_prerequisites
      prerequisites.clear
      self
    end

comment() click to toggle source

First line (or sentence) of all comments. Multiple comments are separated by a “/”.

    # File rake-13.2.1/lib/rake/task.rb, line 322
    def comment
      transform_comments(" / ") { |c| first_sentence(c) }
    end

enhance(deps=nil, &block) click to toggle source

Enhance a task with prerequisites or actions. Returns self.

    # File rake-13.2.1/lib/rake/task.rb, line 115
    def enhance(deps=nil, &block)
      @prerequisites |= deps if deps
      @actions << block if block_given?
      self
    end

execute(args=nil) click to toggle source

Execute the actions associated with this task.

    # File rake-13.2.1/lib/rake/task.rb, line 270
    def execute(args=nil)
      args ||= EMPTY_TASK_ARGS
      if application.options.dryrun
        application.trace "** Execute (dry run) #{name}"
        return
      end
      application.trace "** Execute #{name}" if application.options.trace
      application.enhance_with_matching_rule(name) if @actions.empty?
      if opts = Hash.try_convert(args) and !opts.empty?
        @actions.each { |act| act.call(self, args, **opts) }
      else
        @actions.each { |act| act.call(self, args) }
      end
    end

full_comment() click to toggle source

Full collection of comments. Multiple comments are separated by newlines.

    # File rake-13.2.1/lib/rake/task.rb, line 316
    def full_comment
      transform_comments("\n")
    end

investigation() click to toggle source

Return a string describing the internal state of a task. Useful for debugging.

    # File rake-13.2.1/lib/rake/task.rb, line 354
    def investigation
      result = "------------------------------\n".dup
      result << "Investigating #{name}\n"
      result << "class: #{self.class}\n"
      result <<  "task needed: #{needed?}\n"
      result <<  "timestamp: #{timestamp}\n"
      result << "pre-requisites: \n"
      prereqs = prerequisite_tasks
      prereqs.sort! { |a, b| a.timestamp <=> b.timestamp }
      prereqs.each do |p|
        result << "--#{p.name} (#{p.timestamp})\n"
      end
      latest_prereq = prerequisite_tasks.map(&:timestamp).max
      result <<  "latest-prerequisite time: #{latest_prereq}\n"
      result << "................................\n\n"
      return result
    end

invoke(*args) click to toggle source

Invoke the task if it is needed. Prerequisites are invoked first.

    # File rake-13.2.1/lib/rake/task.rb, line 186
    def invoke(*args)
      task_args = TaskArguments.new(arg_names, args)
      invoke_with_call_chain(task_args, InvocationChain::EMPTY)
    end

name() click to toggle source

Name of the task, including any namespace qualifiers.

    # File rake-13.2.1/lib/rake/task.rb, line 122
    def name
      @name.to_s
    end

needed?() click to toggle source

Is this task needed?

    # File rake-13.2.1/lib/rake/task.rb, line 286
    def needed?
      true
    end

prerequisite_tasks() click to toggle source

List of prerequisite tasks

    # File rake-13.2.1/lib/rake/task.rb, line 61
    def prerequisite_tasks
      (prerequisites + order_only_prerequisites).map { |pre| lookup_prerequisite(pre) }
    end

reenable() click to toggle source

Reenable the task, allowing its tasks to be executed if the task is invoked again.

    # File rake-13.2.1/lib/rake/task.rb, line 147
    def reenable
      @already_invoked = false
      @invocation_exception = nil
    end

set_arg_names(args) click to toggle source

Set the names of the arguments for this task. `args` should be an array of symbols, one for each argument name.

    # File rake-13.2.1/lib/rake/task.rb, line 348
    def set_arg_names(args)
      @arg_names = args.map(&:to_sym)
    end

source() click to toggle source

First source from a rule (nil if no sources)

    # File rake-13.2.1/lib/rake/task.rb, line 93
    def source
      sources.first
    end

sources() click to toggle source

    # File rake-13.2.1/lib/rake/task.rb, line 52
    def sources
      if defined?(@sources)
        @sources
      else
        prerequisites
      end
    end

timestamp() click to toggle source

Timestamp for this task. Basic tasks return the current time for their time stamp. Other tasks can be more sophisticated.

    # File rake-13.2.1/lib/rake/task.rb, line 292
    def timestamp
      Time.now
    end

to_s() click to toggle source

Return task name

    # File rake-13.2.1/lib/rake/task.rb, line 42
    def to_s
      name
    end

|(deps) click to toggle source

Add order only dependencies.

    # File rake-13.2.1/lib/rake/task.rb, line 379
    def |(deps)
      @order_only_prerequisites |= Task.format_deps(deps) - @prerequisites
      self
    end

### Protected Instance Methods

invoke_with_call_chain(task_args, invocation_chain) click to toggle source

Same as invoke, but explicitly pass a call chain to detect circular dependencies.

If multiple tasks depend on this one in parallel, they will all fail if the first execution of this task fails.

    # File rake-13.2.1/lib/rake/task.rb, line 197
    def invoke_with_call_chain(task_args, invocation_chain)
      new_chain = Rake::InvocationChain.append(self, invocation_chain)
      @lock.synchronize do
        begin
          if application.options.trace
            application.trace "** Invoke #{name} #{format_trace_flags}"
          end

          if @already_invoked
            if @invocation_exception
              if application.options.trace
                application.trace "** Previous invocation of #{name} failed #{format_trace_flags}"
              end
              raise @invocation_exception
            else
              return
            end
          end

          @already_invoked = true

          invoke_prerequisites(task_args, new_chain)
          execute(task_args) if needed?
        rescue Exception => ex
          add_chain_to(ex, new_chain)
          @invocation_exception = ex
          raise ex
        end
      end
    end

### Private Instance Methods

first_sentence(string) click to toggle source

Get the first sentence in a string. The sentence is terminated by the first period, exclamation mark, or the end of the line. Decimal points do not count as periods.

    # File rake-13.2.1/lib/rake/task.rb, line 341
    def first_sentence(string)
      string.split(/(?<=\w)(\.|!)[ \t]|(\.$|!)|\n/).first
    end

format_trace_flags() click to toggle source

Format the trace flags for display.

    # File rake-13.2.1/lib/rake/task.rb, line 261
    def format_trace_flags
      flags = []
      flags << "first_time" unless @already_invoked
      flags << "not_needed" unless needed?
      flags.empty? ? "" : "(" + flags.join(", ") + ")"
    end

transform_comments(separator, &block) click to toggle source

Transform the list of comments as specified by the block and join with the separator.

    # File rake-13.2.1/lib/rake/task.rb, line 328
    def transform_comments(separator, &block)
      if @comments.empty?
        nil
      else
        block ||= lambda { |c| c }
        @comments.map(&block).join(separator)
      end
    end