Added code fences for syntax highlighting

Author: Wouter Coppieters

README.md

@@ -27,6 +27,7 @@ Rulp is inspired by the ruby wrapper for the GLPK toolkit and the python LP libr
 
 ## Sample Code
 
+```ruby
 	# maximize
 	#   z = 10 * x + 6 * y + 4 * z
 	#
@@ -62,12 +63,13 @@ Rulp is inspired by the ruby wrapper for the GLPK toolkit and the python LP libr
 	#   Y_i.value == 67
 	#   Z_i.value == 0
 	##
-
+```
 
 ## Usage
 
 #### Variables
 
+```ruby
 	# Rulp variables are initialized as soon as they are needed so there is no
 	# need to initialize them.
 	# They follow a naming convention that defines their type.
@@ -110,7 +112,7 @@ Rulp is inspired by the ruby wrapper for the GLPK toolkit and the python LP libr
 	 #<LV:0x007ffc4cc0d460 @name="Unit8">,
 	 #<LV:0x007ffc4cc0cee8 @name="Unit9">,
 	 #<LV:0x007ffc4cc0c970 @name="Unit10">]
-
+```
 
 ### Variable Constraints
 
@@ -119,6 +121,7 @@ Be careful to use '==' and not '=' when expressing equality.
 Constraints on a variable can only use numeric literals and not other variables.
 Inter-variable constraints should be expressed as problem constrants. (Explained below.)
 
+```ruby
 	X_i < 5
 	X_i.bounds
 	=> "X <= 5"
@@ -130,11 +133,13 @@ Inter-variable constraints should be expressed as problem constrants. (Explained
 	Y_f == 10
 	Y_f.bounds
 	=> "y = 10"
+```
 
 ### Problem constraints
 
 Constraints are added to a problem using the :[] syntax.
 
+```ruby
 	problem = Rulp::Cbc Rulp::Max( 10 * X_i + 6 * Y_i + 4 * Z_i )
 
 	problem[
@@ -146,14 +151,17 @@ Constraints are added to a problem using the :[] syntax.
 	]
 	...
 	problem.solve
+```
 
 You can add multiple constraints at once by comma separating them as seen in the earlier examples:
 
+```ruby
 	Rulp::Cbc Rulp::Max( 10 * X_i + 6 * Y_i + 4 * Z_i ) [
 		                X_i +     Y_i +     Z_i <= 100,
 		           10 * X_i + 4 * Y_i + 5 * Z_i <= 600,
 		           2 *  X_i + 2 * Y_i + 6 * Z_i <= 300
 		          ]
+```
 
 ### Solving or saving 'lp' files
 
@@ -165,61 +173,76 @@ such that the command `which [exec_name]` returns a path. (I.e they must be on y
 
 Given a problem there are multiple ways to initiate a solver.
 
+```ruby
 	@problem = Rulp::Cbc Rulp::Max( 10 * X_i + 6 * Y_i + 4 * Z_i ) [
 	                 X_i +     Y_i +     Z_i <= 100,
 	           	10 * X_i + 4 * Y_i + 5 * Z_i <= 600,
 	           	2 *  X_i + 2 * Y_i + 6 * Z_i <= 300
 						]
+```
 
 Default solver:
 
+```ruby
 	@problem.solve
 	# this will use the solver specified in the environment variable 'SOLVER' by default.
 	# This can be 'scip', 'cbc', or 'glpk'. If no variable is given it uses scip as a default.
+```
 
 If you had a linear equation in a file named 'problem.rb' from the command line you could specify an alternate solver by executing:
 
+```ruby
 	SOLVER=cbc ruby problem.rb
+```
 
 Explicit solver:
 
+```ruby
 	@problem.scip
 	# 	Or
 	@problem.cbc
 	#   Or
 	@problem.glpk
+```
 
 Or
 
+```ruby
 	Rulp::Scip(@problem)
 	Rulp::Glpk(@problem)
 	Rulp::Cbc(@problem)
-
+```
 
 For debugging purposes you may wish to see the input and output files generated and consumed by Rulp.
 To do this you can use the following extended syntax:
 
+```ruby
 	def solve_with(type, open_definition=false, open_solution=false)...
+```
 
 The optional booleans will optionally call the 'open' utility to open the problem definition or the solution. (This utility is installed by default on a mac and will not work if the utility is not on your PATH)
 
-
+```ruby
 	@problem.solve_with(SCIP, true, true)
+```
 
 #### Saving LP files.
 
 You may not wish to use one of the RULP compatible but another solver that is able to read .lp files. (E.g CPLEX or Gurobi) but still want to use Rulp to generate your LP file. In this case you should use Rulp to output your lp problem description to a file of your choice. To do this simply use the following call
 
+```ruby
 	@problem.save("/Users/johndoe/Desktop/myproblem.lp")
+```
 
 OR
-
+```ruby
 	@problem.output("/Users/johndoe/Desktop/myproblem.lp")
+```
 
 You should also be able to call
-
+```ruby
 	@problem.save
-
+```
 Without parameters to be prompted for a save location.
 
 ### Examples.
@@ -230,6 +253,8 @@ Rulp comes bundled with a 'rulp' executable which by default loads the rulp envi
 (Preference for PRY). Once installed you should be able to simply execute 'rulp' to launch this rulp enabled REPL.
 You can then play with and attempt LP and MIP problems straight from the command line.
 
+```ruby
+
 	[1] pry(main)> 13 <= X_i <= 45 # Declare integer variable
 	=> X(i)[undefined]
 
@@ -286,7 +311,7 @@ You can then play with and attempt LP and MIP problems straight from the command
 
 	[10] pry(main)> (2 * X_i + 15 * Y_f).evaluate
 	=> 251.0
-
+```
 
 ### A larger example
 Here is a basic example of how Rulp can help you model problems with a large number of variables.
@@ -298,18 +323,28 @@ of how we could use Rulp to formulate this problem.
 We decide to model each of these possible purchases as a binary variable (as we either purchase them or
 we don't. We can't partially purchase one.)
 
-	# Generate the data randomly for this example.
-	costs, points = [*0..1000].map do |i|
-		[Purchase_b(i) * Random.rand(1.0..3.0), Purchase_b(i) * Random.rand(5.0..10.0)]
-	end.transpose.map(&:sum) #We sum the array of points and array of costs to create a Rulp expression
-
-	# And this is where the magic happens!. We ask rulp to maximise the number of points given
-	# the constraint that costs must be less than $55
-
-	Rulp::Max(points)[
-		costs < 55
-	].solve
-	=> 538.2125623353652 (# You will get a different value as data was generated randomly)
-
-	# Now how do we check which purchases were selected?
-	selected_purchases = [*0..1000].select{|i| Purchase_b(i).value }
+```ruby
+# Generate the data randomly for this example.
+costs, points = [*0..1000].map do |i|
+	[Purchase_b(i) * Random.rand(1.0..3.0), Purchase_b(i) * Random.rand(5.0..10.0)]
+end.transpose.map(&:sum) #We sum the array of points and array of costs to create a Rulp expression
+
+# And this is where the magic happens!. We ask rulp to maximise the number of points given
+# the constraint that costs must be less than $55
+
+Rulp::Max(points)[
+	costs < 55
+].solve
+=> 538.2125623353652 (# You will get a different value as data was generated randomly)
+
+# Now how do we check which purchases were selected?
+selected_purchases = [*0..1000].select do |i|
+	Purchase_b(i).value
+end.map(&Purchase_b)
+=> [Purchase27(b)[true],
+ Purchase86(b)[true],
+ Purchase120(b)[true],
+ Purchase141(b)[true],
+ Purchase154(b)[true],
+ ...
+```

lib/extensions/kernel_extensions.rb

@@ -22,14 +22,14 @@ def method_missing(value, *args)
     if (start <= "Z" && start >= "A")
       case method_name[-1]
       when "b"
-        method_name = method_name[0..(method_name[-2] == "_" ? -3 : -2)] + args.join("_")
-        return BV.send(method_name)
+        method_name = method_name[0..(method_name[-2] == "_" ? -3 : -2)]
+        return BV.send(method_name, args)
       when "i"
-        method_name = method_name[0..(method_name[-2] == "_" ? -3 : -2)] + args.join("_")
-        return IV.send(method_name)
+        method_name = method_name[0..(method_name[-2] == "_" ? -3 : -2)]
+        return IV.send(method_name, args)
       when "f"
-        method_name = method_name[0..(method_name[-2] == "_" ? -3 : -2)] + args.join("_")
-        return LV.send(method_name)
+        method_name = method_name[0..(method_name[-2] == "_" ? -3 : -2)]
+        return LV.send(method_name, args)
       end
     end
     old_method_missing(value, *args)

lib/rulp/lv.rb

@@ -4,44 +4,49 @@
 # These are constructed dynamically by using the special Capitalised variable declaration syntax.
 ##
 class LV
-  attr_reader :name
+  attr_reader :name, :args
   attr_accessor :lt, :lte, :gt, :gte, :value
   include Rulp::Bounds
   include Rulp::Initializers
 
   def to_proc
-    ->(index){ send(self.meth(index)) }
+    ->(index){ send(self.meth, index) }
   end
 
-  def meth(*args)
-    "#{self.name}#{args.join("_")}_#{self.suffix}"
+  def meth
+    "#{self.name}_#{self.suffix}"
   end
 
   def suffix
     "f"
   end
 
   def self.method_missing(name, *args)
-    return self.definition( "#{name}#{args.join("_")}" )
+    return self.definition(name, args)
   end
 
   def self.const_missing(name)
     return self.definition(name)
   end
 
-  def self.definition(name)
-    self.class.send(:define_method, name){
-      defined = LV::names_table["#{name}"]
-      if defined && defined.class != self
-        raise StandardError.new("ERROR:\n#{name} was already defined as a variable of type #{defined.class}."+
-                                "You are trying to redefine it as a variable of type #{self}")
-      elsif(!defined)
-        self.new(name)
+  def self.definition(name, args)
+    identifier = "#{name}#{args.join("_")}"
+    self.class.send(:define_method, identifier){|index=nil|
+      if index
+        self.definition(name, index)
       else
-        defined
+        defined = LV::names_table["#{identifier}"]
+        if defined && defined.class != self
+          raise StandardError.new("ERROR:\n#{name} was already defined as a variable of type #{defined.class}."+
+                                  "You are trying to redefine it as a variable of type #{self}")
+        elsif(!defined)
+          self.new(name, args)
+        else
+          defined
+        end
       end
     }
-    return self.send(name) || self.new(name)
+    return self.send(identifier) || self.new(name, args)
   end
 
   def * (numeric)
@@ -73,7 +78,7 @@ def value
   end
 
   def inspect
-    "#{name}(#{suffix})[#{value || 'undefined'}]"
+    "#{name}#{args.join("-")}(#{suffix})[#{value || 'undefined'}]"
   end
 end
 

lib/rulp/rulp_initializers.rb

@@ -1,9 +1,10 @@
 module Rulp
   module Initializers
-    def initialize(name)
-      raise StandardError.new("Variable with the name #{name} of a different type (#{LV::names_table[name].class}) already exists") if LV::names_table["#{name}"]
-      LV::names_table["#{name}"] = self
+    def initialize(name, args)
       @name = name
+      @args = args
+      raise StandardError.new("Variable with the name #{self} of a different type (#{LV::names_table[self.to_s].class}) already exists") if LV::names_table[self.to_s]
+      LV::names_table[self.to_s] = self
     end
 
     def self.included(base)
@@ -21,7 +22,7 @@ def clear
     end
 
     def to_s
-      "#{self.name}"
+      "#{self.name}#{self.args.join("_")}"
     end
   end
 end

lib/solvers/cbc.rb

@@ -17,7 +17,7 @@ def store_results(variables)
       vars_by_name[cols[1].to_s] = cols[2].to_f
     end
     variables.each do |var|
-      var.value = vars_by_name[var.name.to_s].to_f
+      var.value = vars_by_name[var.to_s].to_f
     end
     return objective
   end

lib/solvers/scip.rb

@@ -23,7 +23,7 @@ def store_results(variables)
       vars_by_name[cols[0].to_s] = cols[1].to_f
     end
     variables.each do |var|
-      var.value = vars_by_name[var.name.to_s].to_f
+      var.value = vars_by_name[var.to_s].to_f
     end
 
     return objective

rulp.gemspec

@@ -1,6 +1,6 @@
 Gem::Specification.new do |s|
   s.name        = 'rulp'
-  s.version     = '0.0.5'
+  s.version     = '0.0.6'
   s.date        = Date.today
   s.summary     = "Ruby Linear Programming"
   s.description = "A simple Ruby LP description DSL"