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Use isinstance rather than comparing class attribute

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This allows to create subclasses
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Salvo 'LtWorf' Tomaselli 2015-07-14 11:09:42 +02:00
parent 73dd14d9dd
commit f787630edb
1 changed files with 6 additions and 4 deletions
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10
relational/relation.py
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@ -94,7 +94,7 @@ class relation (object):
It is not exactely related to relational algebra. Just a method used
internally.
Will raise an exception if they don't share the same attributes'''
if (self.__class__ != other.__class__):
if not isinstance(other, relation):
raise Exception('Expected an instance of the same class')
elif self.header == other.header:
return other
@ -113,7 +113,7 @@ class relation (object):
# Fills the attributes dictionary with the values of the tuple
attributes = {attr: i[j].autocast()
for j, attr in enumerate(self.header)
}
}
try:
if eval(expr, attributes):
@ -129,7 +129,9 @@ class relation (object):
cause an exception.
It is possible to use rename on attributes and then use the product'''
if (self.__class__ != other.__class__)or(self.header.sharedAttributes(other.header) != 0):
if (not isinstance(other, relation)):
raise Exception('Operand must be a relation')
if self.header.sharedAttributes(other.header) != 0:
raise Exception(
'Unable to perform product on relations with colliding attributes'
)
@ -347,7 +349,7 @@ class relation (object):
def __eq__(self, other):
'''Returns true if the relations are the same, ignoring order of items.
This operation is rather heavy, since it requires sorting and comparing.'''
if self.__class__ != other.__class__:
if not isinstance(other, relation):
return False
if set(self.header) != set(other.header):