Fix flake8 errors and warnings

We add the flake8 configuration used so we ensure everyone uses the same.
We remove the usage of __all__ for non public API.
When possible, we rationalize the class name according to its __name__ and module.

issue9082
review297061002

.flake8

@@ -0,0 +1,2 @@
+[flake8]
+ignore=E123,E124,E126,E128,W503

__init__.py

@@ -2,14 +2,14 @@
 # this repository contains the full copyright notices and license terms.
 
 from trytond.pool import Pool
-from .sale import *
+from . import sale
 
 
 def register():
     Pool.register(
-        SalePromotion,
-        SalePromotion_Product,
-        SalePromotion_ProductCategory,
-        Sale,
-        SaleLine,
+        sale.Promotion,
+        sale.Promotion_Product,
+        sale.Promotion_ProductCategory,
+        sale.Sale,
+        sale.Line,
         module='sale_promotion', type_='model')

sale.py

@@ -16,9 +16,6 @@ from trytond.tools import decistmt
 from trytond.modules.product import price_digits
 from .exceptions import FormulaError
 
-__all__ = ['Sale', 'SaleLine',
-    'SalePromotion', 'SalePromotion_Product', 'SalePromotion_ProductCategory']
-
 
 class Sale(metaclass=PoolMeta):
     __name__ = 'sale.sale'
@@ -70,7 +67,7 @@ class Sale(metaclass=PoolMeta):
             promotion.apply(self)
 
 
-class SaleLine(metaclass=PoolMeta):
+class Line(metaclass=PoolMeta):
     __name__ = 'sale.line'
 
     draft_unit_price = fields.Numeric('Draft Unit Price',
@@ -82,7 +79,7 @@ class SaleLine(metaclass=PoolMeta):
             ])
 
 
-class SalePromotion(
+class Promotion(
         DeactivableMixin, ModelSQL, ModelView, MatchMixin):
     'Sale Promotion'
     __name__ = 'sale.promotion'
@@ -149,7 +146,7 @@ class SalePromotion(
 
     @classmethod
     def validate(cls, promotions):
-        super(SalePromotion, cls).validate(promotions)
+        super().validate(promotions)
         for promotion in promotions:
             promotion.check_formula()
 
@@ -215,7 +212,7 @@ class SalePromotion(
             pattern = pattern.copy()
             if self.quantity > pattern.pop('quantity'):
                 return False
-        return super(SalePromotion, self).match(pattern)
+        return super().match(pattern)
 
     def is_valid_sale_line(self, line):
 
@@ -278,7 +275,7 @@ class SalePromotion(
         return max(simple_eval(decistmt(self.formula), **context), Decimal(0))
 
 
-class SalePromotion_Product(ModelSQL):
+class Promotion_Product(ModelSQL):
     'Sale Promotion - Product'
     __name__ = 'sale.promotion-product.product'
 
@@ -288,7 +285,7 @@ class SalePromotion_Product(ModelSQL):
         required=True, ondelete='CASCADE')
 
 
-class SalePromotion_ProductCategory(ModelSQL):
+class Promotion_ProductCategory(ModelSQL):
     "Sale Promotion - Product Category"
     __name__ = 'sale.promotion-product.category'
 

setup.py

@@ -79,8 +79,8 @@ setup(name=name,
     keywords='tryton sale promotion',
     package_dir={'trytond.modules.sale_promotion': '.'},
     packages=(
-        ['trytond.modules.sale_promotion'] +
-        ['trytond.modules.sale_promotion.%s' % p for p in find_packages()]
+        ['trytond.modules.sale_promotion']
+        + ['trytond.modules.sale_promotion.%s' % p for p in find_packages()]
         ),
     package_data={
         'trytond.modules.sale_promotion': (info.get('xml', [])
@@ -93,7 +93,8 @@ setup(name=name,
         'Intended Audience :: Developers',
         'Intended Audience :: Financial and Insurance Industry',
         'Intended Audience :: Legal Industry',
-        'License :: OSI Approved :: GNU General Public License v3 or later (GPLv3+)',
+        'License :: OSI Approved :: '
+        'GNU General Public License v3 or later (GPLv3+)',
         'Natural Language :: Bulgarian',
         'Natural Language :: Catalan',
         'Natural Language :: Chinese (Simplified)',