OpenEuphoria

1. Classless class-oriented programming

• Posted by jmduro Oct 24, 2021
• 1103 views

In a previous article I showed a preprocessor to allow class-like programming. There are many other ways to do the job.

Here is one which could even be used with previous preprocessor.

Here is the library (classes.e):

namespace classes 
 
include std/convert.e 
 
-- INTERNAL CONSTANTS 
constant CLASS_NAME   =1, CLASS_PROPERTY=2,   CLASS_METHOD=3 
constant PROPERTY_NAME=1, PROPERTY_VALUE=2 
constant METHOD_NAME  =1, METHOD_ROUTINE_ID=2 
constant CLASS_ID     =1, ENTITY_VALUES=2 
 
-- INTERNAL VARIABLES 
public sequence classes = {}, entities = {} 
 
-- INTERNAL FUNCTIONS 
procedure error_message(sequence msg) 
  puts(2, "Error: " & msg & "\n")  
  abort(1)  
end procedure 
 
-- GLOBAL CLASS FUNCTIONS 
 
-- define a ClassName 
-- given the ClassName Name returns the ClassName ID 
public function class(sequence className) 
  classes = append(classes, {className, {}, {}}) 
  return length(classes) 
end function 
 
-- define a ClassName property 
public procedure addProperty(integer classID, sequence propertyName, object defaultValue) 
  if classID > 0 then 
    classes[classID][CLASS_PROPERTY] = append(classes[classID][CLASS_PROPERTY], {propertyName, defaultValue}) 
  else 
    error_message(sprintf("addProperty(%d, \"%s\", %s): no ClassName parameter\n", 
                      {classID, propertyName, to_string(defaultValue)})) 
  end if 
end procedure 
 
-- define a ClassName method 
public procedure addMethod(integer classID, sequence methodName, integer routineId) 
  if classID > 0 then 
    classes[classID][CLASS_METHOD] = append(classes[classID][CLASS_METHOD], {methodName, routineId}) 
  else 
    error_message(sprintf("addMethod(%d, \"%s\", %d): no ClassName parameter\n", 
                      {classID, methodName, routineId})) 
  end if 
end procedure 
 
-- get the class name of a class ID 
public function findClass(sequence name) 
  for i = 1 to length(classes) do 
    if equal(name, classes[i][CLASS_NAME]) then return i end if 
  end for 
  return 0 
end function 
 
-- find property 
public function findProperty(integer classID, sequence property) 
  for i = 1 to length(classes[classID][CLASS_PROPERTY]) do 
    if equal(property, classes[classID][CLASS_PROPERTY][i][PROPERTY_NAME]) then 
      return i 
    end if 
  end for 
  return 0 
end function 
 
-- find method routine_id 
public function findMethod(integer classID, sequence method) 
  for i = 1 to length(classes[classID][CLASS_METHOD]) do 
    if equal(method, classes[classID][CLASS_METHOD][i][METHOD_NAME]) then 
      return classes[classID][CLASS_METHOD][i][METHOD_ROUTINE_ID] 
    end if 
  end for 
  return 0 
end function 
 
-- GLOBAL ENTITY FUNCTIONS 
 
-- create an Entity of the class ClassName 
public function new(integer classID) 
  sequence class = classes[classID] 
  sequence values =  {} 
  for i = 1 to length(class[CLASS_PROPERTY]) do 
    values = append(values, class[CLASS_PROPERTY][i][PROPERTY_VALUE]) 
  end for 
  entities = append(entities, {classID, values}) 
  return length(entities) 
end function 
 
-- get entity class ID 
public function getClassID(integer entityID) 
  return entities[entityID][CLASS_ID] 
end function 
 
-- get property value 
public function getProperty(integer entityID, sequence property, object defaultValue=0) 
  integer classID = entities[entityID][CLASS_ID] 
  integer propertyID = findProperty(classID, property) 
  if propertyID then 
    return entities[entityID][ENTITY_VALUES][propertyID] 
  end if 
  return defaultValue 
end function 
 
-- set property value 
public procedure setProperty(integer entityID, sequence property, object val) 
  integer classID = entities[entityID][CLASS_ID] 
  integer propertyID = findProperty(classID, property) 
  if propertyID then 
    entities[entityID][ENTITY_VALUES][propertyID] = val 
  end if 
end procedure 
 
-- call a method (function) within an Entity 
public function callMethod(integer entityID, sequence method, object methodParams= {}) 
  integer classID = entities[entityID][CLASS_ID] 
  integer methodID = findMethod(classID, method) 
  if methodID then 
    return call_func(methodID, {entityID, methodParams}) 
  end if 
  return -1 
end function 

3. Re: Classless class-oriented programming

• Posted by dr_can Oct 31, 2021
• 981 views

The relationship between OOP, as a set of principles, and OE has long been an interest of mine.

As it says somewhere in the RDS documentation, Euphoria has (many of) the features of OOP without the formal syntax adopted by OOP language developers. To this end, I have constructed what I think of as a neat, Euphoria-like, approach to OOP. It can be found at https://github.com/CANewbould/OE4OOP. I have also included a very primitive dot-notation pre-processor, if only to allow code to copy the "standard" OOP layout.

I should appreciate your reaction.