Refactor exception handling; cleanup

README.md

@@ -31,7 +31,8 @@ To show all known classes, semesters, and assignments:
 
     rake list
 
-To load a roster for a specific semester:
+To load a roster (a newline-delimited list of student identifiers) for a
+specific semester:
 
     rake roster cs123 myroster.csv semester=sp16
 

lib/kgrader/cli.rb

@@ -26,19 +26,19 @@ module KGrader
     end
 
     def roster(course, semester, rosterfile)
-      course = fetch_course course
+      course = Course.new(@fs, course)
       semester ||= course.current_semester
       course.roster(semester).load rosterfile
     end
 
     def grade(course, semester, assignment, options = {})
-      course = fetch_course course
+      course = Course.new(@fs, course)
       semester ||= course.current_semester
       course.task(semester, assignment).grade options
     end
 
     def commit(course, semester, assignment, options = {})
-      course = fetch_course course
+      course = Course.new(@fs, course)
       semester ||= course.current_semester
       course.task(semester, assignment).commit options
     end
@@ -58,12 +58,6 @@ module KGrader
     end
 
     private
-    def fetch_course(course)
-      Course.new(@fs, course)
-    rescue FilesystemError
-      KGrader::die "unknown course"
-    end
-
     def reset_jail
       FileUtils.rm_rf @fs.jail
       FileUtils.mkdir @fs.jail

lib/kgrader/course.rb

@@ -11,6 +11,8 @@ module KGrader
 
       @config = @fs.load @fs.course_config(@name)
       @rosters = {}
+    rescue FilesystemError
+      raise CourseError, "unknown or invalid course: #{name}"
     end
 
     def roster(semester)
@@ -30,12 +32,7 @@ module KGrader
     end
 
     def current_semester
-      case @config['semesters']
-      when 'faspYY'
-        KGrader::season + DateTime.now.strftime('%y')
-      when 'faspYYYY'
-        KGrader::season + DateTime.now.strftime('%Y')
-      end
+      KGrader::current_semester @config['semesters']
     end
   end
 end

lib/kgrader/errors.rb

@@ -2,6 +2,18 @@ module KGrader
   class KGraderError < StandardError
   end
 
+  class ArgumentError < KGraderError
+  end
+
   class FilesystemError < KGraderError
   end
+
+  class ConfigError < KGraderError
+  end
+
+  class CourseError < KGraderError
+  end
+
+  class RosterError < KGraderError
+  end
 end

lib/kgrader/filesystem.rb

@@ -52,10 +52,10 @@ module KGrader
       when '.csv'
         File.read(path).split("\n").map! { |line| line.split "," }
       else
-        raise FilesystemError, "unknown file type"
+        raise FilesystemError, "unknown file type: #{path}"
       end
     rescue SystemCallError  # Errno::ENOENT, etc.
-      raise FilesystemError, "can't read file"
+      raise FilesystemError, "can't read file: #{path}"
     end
   end
 end

lib/kgrader/roster.rb

@@ -13,10 +13,14 @@ module KGrader
       @students = @fs.load(filename).map! { |item| item.first }
       FileUtils.mkdir_p File.dirname(rosterfile)
       File.write rosterfile, @students.join("\n")
+    rescue FilesystemError => err
+      raise RosterError, err
     end
 
     def students
       @students ||= @fs.load(rosterfile).map! { |item| item.first }
+    rescue FilesystemError
+      raise RosterError, "unknown semester: #{semester}"
     end
 
     private

lib/kgrader/task.rb

@@ -6,23 +6,32 @@ module KGrader
       @course = course
       @semester = semester
       @assignment = assignment
-      @roster = @course.roster @semester
+      @students = @course.roster(@semester).students
     end
 
     def grade(options = {})
-      students = @roster.students
+      students = @students
       students &= options[:students] unless options[:students].nil?
 
+      due = options.fetch(:due, Time.now)
+      fetch = options.fetch(:fetch, true)
+      regrade = options.fetch(:regrade, false)
+
       # TODO
       puts "Grading #{@course.name}:#{@semester} assignment #{@assignment}..."
-      puts "- options: #{options}"
       puts "- students: #{students.inspect}"
+      puts "- due:      #{due}"
+      puts "- fetch:    #{fetch}"
+      puts "- regrade:  #{regrade}"
     end
 
     def commit(options = {})
+      students = @students
+      students &= options[:students] unless options[:students].nil?
+
       # TODO
       puts "Committing #{@course.name}:#{@semester} assignment #{@assignment}..."
-      puts "- options: #{options}"
+      puts "- students: #{students.inspect}"
     end
   end
 end

lib/kgrader/util.rb

@@ -1,10 +1,6 @@
-require 'date'
+require 'time'
 
 module KGrader
-  def self.die(error)
-    Kernel::abort "fatal: #{error}"
-  end
-
   def self.parse_args(raw, num, keywords)
     args = []
     options = {}
@@ -13,7 +9,9 @@ module KGrader
       if arg.include? '='
         key, val = arg.split('=', 2)
         key = key.to_sym
-        die "unknown keyword #{key}" unless keywords.include? key
+        unless keywords.include? key
+          raise ArgumentError, "unknown keyword: #{key}"
+        end
         options[key] = case keywords[key]
         when :string
           val
@@ -21,20 +19,28 @@ module KGrader
           %w(true yes 1 t y).include? val.downcase
         when :array
           val.split(",").map! { |x| x.strip.downcase }
-        when :datetime
-          DateTime.parse(val)
+        when :time
+          Time.parse(val)
         end
       else
         args << arg
       end
     end
 
-    die "too few arguments" if args.size < num
-    die "too many arguments" if args.size > num
+    raise ArgumentError, "too few arguments" if args.size < num
+    raise ArgumentError, "too many arguments" if args.size > num
     return args, options
   end
 
-  def self.season
-    DateTime.now.strftime('%m').to_i <= 6 ? 'sp' : 'fa'
+  def self.current_semester(format)
+    season = Time.now.strftime('%m').to_i <= 6 ? 'sp' : 'fa'
+    case format
+    when 'faspYY'
+      season + Time.now.strftime('%y')
+    when 'faspYYYY'
+      season + Time.now.strftime('%Y')
+    else
+      raise ConfigError, "unknown semester format: #{format}"
+    end
   end
 end

rakefile

@@ -1,13 +1,21 @@
 require_relative 'lib/kgrader'
 
-def cli
-  KGrader::CLI.new Rake.application.original_dir
+def die(error)
+  abort "fatal: [#{error.class}] #{error}"
+end
+
+def run
+  yield KGrader::CLI.new Rake.application.original_dir
+rescue KGrader::KGraderError => err
+  die err
 end
 
 def parse_args(num, keywords = {})
   args, options = KGrader::parse_args ARGV.drop(1), num, keywords
   args.each { |arg| task arg.to_sym {} }
   args + [options]
+rescue KGrader::KGraderError => err
+  die err
 end
 
 task :default => :help do ; end
@@ -24,31 +32,31 @@ task :help do
 end
 
 task :list do
-  cli.list
+  run { |cli| cli.list }
 end
 
 task :roster do
   course, rosterfile, options = parse_args 2, { :semester => :string }
-  cli.roster course, options[:semester], rosterfile
+  run { |cli| cli.roster course, options[:semester], rosterfile }
 end
 
 task :grade do
   course, assignment, options = parse_args 2,
-    { :semester => :string, :students => :array, :due => :datetime,
+    { :semester => :string, :students => :array, :due => :time,
       :fetch => :bool, :regrade => :bool }
-  cli.grade course, options[:semester], assignment, options
+  run { |cli| cli.grade course, options[:semester], assignment, options }
 end
 
 task :commit do
   course, assignment, options = parse_args 2,
     { :semester => :string, :students => :array }
-  cli.commit course, options[:semester], assignment, options
+  run { |cli| cli.commit course, options[:semester], assignment, options }
 end
 
 task :clean do
-  cli.clean
+  run { |cli| cli.clean }
 end
 
 task :clobber do
-  cli.clobber
+  run { |cli| cli.clobber }
 end