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0

I'm currently building a class model with a save() method for inserting/updating it in a database like this:

class Session(object):

 #
 # ...
 #

 def save(self):
 try:
 database = Database()
 if self.id == None:
 self.id = database.insert(
 '<table>',
 [<list of columns>],
 [<list of values>]
 )
 if self.id == False:
 raise RuntimeError('Database insert failed for Session class.')
 else:
 if not database.update(
 '<table>',
 [<list of columns>],
 [<list of values>],
 [<list of columns>],
 [<list of values>]
 ):
 raise RuntimeError('Database update failed for Session class.')
 except (RuntimeError):
 print(RuntimeError)
 database.disconnect()
 return True

I'm creating the Database object Database() within the save method of my Session class. However, I'm wondering if the objects __del__ automatically gets called when the Session class method has finished. If so, I would rather have database.disconnect() running inside the Database objects __del__ method instead of in the current Session class method.

I'm not quite sure how Python handles objects within functions, will I get memory problems if I make to many objects without properly deleting old ones?

My question differs somewhat from the possible duplicate suggest below because I'm asking for a combination of what methods are called for objects that are being finalized inside another object while also asking if they are garbage collected at the end of their scope.

python class python-object

share|improve this question

edited Mar 8 at 16:23

Gjert G

asked Mar 8 at 15:47

Gjert GGjert G

27211029

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  You should use with to open your Database. It'll close automatically.
  
  – IMCoins
  Mar 8 at 15:52
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Objects created in a function/method are within that function's scope. When the function returns those objects will go out of scope and be garbage collected if there are no other references to them. - 9.2. Python Scopes and Namespaces 4.2. Naming and binding
  
  – wwii
  Mar 8 at 16:16
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @GjertG Scope applies to variables, not objects. In languages with automatic memory management, objects are deleted when it's no longer possible to access the object. The only relationship with scope is that if there's just one variable referencing an object, it becomes inaccessible when the variable's scope ends.
  
  – Barmar
  Mar 8 at 16:32
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  stackoverflow.com/questions/1481488/… is a good explanation about __del__.
  
  – Barmar
  Mar 8 at 16:35
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Near the end of 3.1. Objects, values and types there is a paragraph talking about explicitly closing some objects and the use of with or try/finally statements. I'll let the community decide if it's a dupe. Maybe with a little research you can ... answer my own question?
  
  – wwii
  Mar 8 at 16:36
  

  
  
  
  

 | 
show 10 more comments

0

I'm currently building a class model with a save() method for inserting/updating it in a database like this:

class Session(object):

 #
 # ...
 #

 def save(self):
 try:
 database = Database()
 if self.id == None:
 self.id = database.insert(
 '<table>',
 [<list of columns>],
 [<list of values>]
 )
 if self.id == False:
 raise RuntimeError('Database insert failed for Session class.')
 else:
 if not database.update(
 '<table>',
 [<list of columns>],
 [<list of values>],
 [<list of columns>],
 [<list of values>]
 ):
 raise RuntimeError('Database update failed for Session class.')
 except (RuntimeError):
 print(RuntimeError)
 database.disconnect()
 return True

I'm creating the Database object Database() within the save method of my Session class. However, I'm wondering if the objects __del__ automatically gets called when the Session class method has finished. If so, I would rather have database.disconnect() running inside the Database objects __del__ method instead of in the current Session class method.

I'm not quite sure how Python handles objects within functions, will I get memory problems if I make to many objects without properly deleting old ones?

My question differs somewhat from the possible duplicate suggest below because I'm asking for a combination of what methods are called for objects that are being finalized inside another object while also asking if they are garbage collected at the end of their scope.

python class python-object

share|improve this question

edited Mar 8 at 16:23

Gjert G

asked Mar 8 at 15:47

Gjert GGjert G

27211029

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  You should use with to open your Database. It'll close automatically.
  
  – IMCoins
  Mar 8 at 15:52
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Objects created in a function/method are within that function's scope. When the function returns those objects will go out of scope and be garbage collected if there are no other references to them. - 9.2. Python Scopes and Namespaces 4.2. Naming and binding
  
  – wwii
  Mar 8 at 16:16
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @GjertG Scope applies to variables, not objects. In languages with automatic memory management, objects are deleted when it's no longer possible to access the object. The only relationship with scope is that if there's just one variable referencing an object, it becomes inaccessible when the variable's scope ends.
  
  – Barmar
  Mar 8 at 16:32
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  stackoverflow.com/questions/1481488/… is a good explanation about __del__.
  
  – Barmar
  Mar 8 at 16:35
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Near the end of 3.1. Objects, values and types there is a paragraph talking about explicitly closing some objects and the use of with or try/finally statements. I'll let the community decide if it's a dupe. Maybe with a little research you can ... answer my own question?
  
  – wwii
  Mar 8 at 16:36
  

  
  
  
  

 | 
show 10 more comments

I'm currently building a class model with a save() method for inserting/updating it in a database like this:

class Session(object):

 #
 # ...
 #

 def save(self):
 try:
 database = Database()
 if self.id == None:
 self.id = database.insert(
 '<table>',
 [<list of columns>],
 [<list of values>]
 )
 if self.id == False:
 raise RuntimeError('Database insert failed for Session class.')
 else:
 if not database.update(
 '<table>',
 [<list of columns>],
 [<list of values>],
 [<list of columns>],
 [<list of values>]
 ):
 raise RuntimeError('Database update failed for Session class.')
 except (RuntimeError):
 print(RuntimeError)
 database.disconnect()
 return True

I'm creating the Database object Database() within the save method of my Session class. However, I'm wondering if the objects __del__ automatically gets called when the Session class method has finished. If so, I would rather have database.disconnect() running inside the Database objects __del__ method instead of in the current Session class method.

I'm not quite sure how Python handles objects within functions, will I get memory problems if I make to many objects without properly deleting old ones?

My question differs somewhat from the possible duplicate suggest below because I'm asking for a combination of what methods are called for objects that are being finalized inside another object while also asking if they are garbage collected at the end of their scope.

python class python-object

share|improve this question

edited Mar 8 at 16:23

Gjert G

asked Mar 8 at 15:47

Gjert GGjert G

27211029

class Session(object):

 #
 # ...
 #

 def save(self):
 try:
 database = Database()
 if self.id == None:
 self.id = database.insert(
 '<table>',
 [<list of columns>],
 [<list of values>]
 )
 if self.id == False:
 raise RuntimeError('Database insert failed for Session class.')
 else:
 if not database.update(
 '<table>',
 [<list of columns>],
 [<list of values>],
 [<list of columns>],
 [<list of values>]
 ):
 raise RuntimeError('Database update failed for Session class.')
 except (RuntimeError):
 print(RuntimeError)
 database.disconnect()
 return True

share|improve this question

edited Mar 8 at 16:23

Gjert G

asked Mar 8 at 15:47

Gjert GGjert G

27211029

share|improve this question

edited Mar 8 at 16:23

Gjert G

asked Mar 8 at 15:47

Gjert GGjert G

27211029

asked Mar 8 at 15:47

Gjert GGjert G

27211029

asked Mar 8 at 15:47

Gjert GGjert G

27211029