Starting Sheerka, learning Python

core/sheerka.py

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+import os
+from dataclasses import dataclass
+
+from core.concept import Concept
+
+
+class Singleton(type):
+    _instances = {}
+
+    def __call__(cls, *args, **kwargs):
+        if cls not in cls._instances:
+            cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
+        return cls._instances[cls]
+
+
+@dataclass
+class ReturnValue:
+    """
+    Class that handle the return of a concept
+    To avoid using the try/except pattern for each and every call
+    To give context (ie return message) even when the call is successful
+    """
+    status: bool
+    value: Concept
+    message: str = None
+
+
+class Sheerka(Concept, metaclass=Singleton):
+    """
+    Main controller for the project
+    """
+
+    NAME = "Sheerka"
+    UNKNOWN_CONCEPT_NAME = "Unknown Concept"
+    ERROR_CONCEPT_NAME = "Error"
+    SUCCESS_CONCEPT_NAME = "Success"
+
+    def __init__(self):
+        super().__init__(Sheerka.NAME)
+
+        # ist of all concepts known be the system
+        self.concepts = []
+
+        # At a given point of time, (TODO: in a specific contexts), somme concepts are instantiated
+        # ex: File is a concept, but File('foo.txt') is an instance
+        self.instances = []  # list of actual instances
+
+        # List of the known rules by the system
+        # ex: hello => say('hello')
+        self.rules = []
+
+        self.create_builtin_concept()
+
+    def create_builtin_concept(self):
+        self.concepts.append(self)
+        self.concepts.append(Concept(Sheerka.UNKNOWN_CONCEPT_NAME))
+        self.concepts.append(Concept(Sheerka.SUCCESS_CONCEPT_NAME))
+        self.concepts.append(Concept(Sheerka.ERROR_CONCEPT_NAME))
+
+    def initialize(self, root_folder):
+        # create the folder configuration folder if needed
+        try:
+            if not os.path.exists(root_folder):
+                os.makedirs(root_folder)
+        except IOError as e:
+            return ReturnValue(False, self.get_concept(Sheerka.ERROR_CONCEPT_NAME, True), e)
+
+        return ReturnValue(True, self.get_concept(Sheerka.SUCCESS_CONCEPT_NAME, True))
+
+    def get_concept(self, name, is_builtin=False):
+        for concept in self.concepts:
+            if concept.name == name and concept.is_builtin == is_builtin:
+                return concept
+        return self.concepts[1]
+
+    @staticmethod
+    def concept_equals(concept1, concept2):
+        if concept1 is None and concept2 is None:
+            return True
+
+        if concept1 is None or concept2 is None:
+            return False
+
+        return concept1.id == concept2.id