PEP-8 fix & simplify some code (#26)

* PEP-8 fix change tab to space indentation
* Add __init__.py to src dir
* Simplify some code
* Fix error if speriod not defined
* Fix error if slength not defined & backward None for speriod

__init__.py

@@ -1,4 +1,4 @@
 from paymentwall.base import Paymentwall
 from paymentwall.product import Product
 from paymentwall.widget import Widget
-from paymentwall.pingback import Pingback 
+from paymentwall.pingback import Pingback

paymentwall/__init__.py

@@ -0,0 +1,8 @@
+from __future__ import absolute_import
+
+from .base import Paymentwall
+from .pingback import Pingback
+from .product import Product
+from .widget import Widget
+
+__all__ = ['Paymentwall', 'Pingback', 'Product', 'Widget']

paymentwall/base.py

@@ -3,86 +3,85 @@
 
 class Paymentwall:
 
-	VERSION = '1.0.0'
-
-	API_VC = 1
-	API_GOODS = 2
-	API_CART = 3
-
-	VC_CONTROLLER = 'ps'
-	GOODS_CONTROLLER = 'subscription'
-	CART_CONTROLLER = 'cart'
-
-	DEFAULT_SIGNATURE_VERSION = 3
-	SIGNATURE_VERSION_1 = 1
-	SIGNATURE_VERSION_2 = 2
-	SIGNATURE_VERSION_3 = 3
-
-	errors = []
-
-	api_type = None
-	app_key = None
-	secret_key = None
-
-	@classmethod
-	def set_api_type(cls, api_type):
-		cls.api_type = api_type
-
-	@classmethod
-	def get_api_type(cls):
-		return cls.api_type
-
-	@classmethod
-	def set_app_key(cls, app_key):
-		cls.app_key = app_key
-
-	@classmethod
-	def get_app_key(cls):
-		return cls.app_key
-
-	@classmethod
-	def set_secret_key(cls, secret_key):
-		cls.secret_key = secret_key
-
-	@classmethod
-	def get_secret_key(cls):
-		return cls.secret_key
-
-	@classmethod
-	def append_to_errors(cls, err):
-		cls.errors.append(err)
-
-	@classmethod
-	def get_errors(cls):
-		return cls.errors
-
-	@classmethod
-	def get_error_summary(cls):
-		return '\n'.join(cls.get_errors())
-
-	#
-	# Helper functions
-	#
-	@classmethod
-	def is_empty(cls, dictionary, key):
-		if isinstance(dictionary, dict):
-			if key in dictionary:
-				if dictionary[key]:
-					return False
-			return True
-
-	@classmethod
-	def array_merge(cls, first_array, second_array):
-		if isinstance(first_array, list) and isinstance(second_array, list):
-			return first_array + second_array
-		elif isinstance(first_array, dict) and isinstance(second_array, dict):
-			return dict(list(first_array.items()) + list(second_array.items()))
-		elif isinstance(first_array, set) and isinstance(second_array, set):
-			return first_array.union(second_array)
-		return False
-
-	@classmethod
-	def hash(cls, string, library_type):
-		hashed_string = hashlib.md5() if library_type == 'md5' else hashlib.sha256()
-		hashed_string.update(string.encode('utf-8'))
-		return hashed_string.hexdigest()
+    VERSION = '1.0.0'
+
+    API_VC = 1
+    API_GOODS = 2
+    API_CART = 3
+
+    VC_CONTROLLER = 'ps'
+    GOODS_CONTROLLER = 'subscription'
+    CART_CONTROLLER = 'cart'
+
+    DEFAULT_SIGNATURE_VERSION = 3
+    SIGNATURE_VERSION_1 = 1
+    SIGNATURE_VERSION_2 = 2
+    SIGNATURE_VERSION_3 = 3
+
+    errors = []
+
+    api_type = None
+    app_key = None
+    secret_key = None
+
+    @classmethod
+    def set_api_type(cls, api_type):
+        cls.api_type = api_type
+
+    @classmethod
+    def get_api_type(cls):
+        return cls.api_type
+
+    @classmethod
+    def set_app_key(cls, app_key):
+        cls.app_key = app_key
+
+    @classmethod
+    def get_app_key(cls):
+        return cls.app_key
+
+    @classmethod
+    def set_secret_key(cls, secret_key):
+        cls.secret_key = secret_key
+
+    @classmethod
+    def get_secret_key(cls):
+        return cls.secret_key
+
+    @classmethod
+    def append_to_errors(cls, err):
+        cls.errors.append(err)
+
+    @classmethod
+    def get_errors(cls):
+        return cls.errors
+
+    @classmethod
+    def get_error_summary(cls):
+        return '\n'.join(cls.get_errors())
+
+    #
+    # Helper functions
+    #
+    @classmethod
+    def is_empty(cls, dictionary, key):
+        if isinstance(dictionary, dict):
+            if key in dictionary and dictionary[key]:
+                return False
+            return True
+
+    @classmethod
+    def array_merge(cls, first_array, second_array):
+        if isinstance(first_array, list) and isinstance(second_array, list):
+            return first_array + second_array
+        elif isinstance(first_array, dict) and isinstance(second_array, dict):
+            return dict(list(first_array.items()) + list(second_array.items()))
+        elif isinstance(first_array, set) and isinstance(second_array, set):
+            return first_array.union(second_array)
+        return False
+
+    @classmethod
+    def hash(cls, string, library_type):
+        hashed_string = hashlib.md5() if library_type == 'md5' else hashlib.sha256()
+        hashed_string.update(string.encode('utf-8'))
+        return hashed_string.hexdigest()