How to get instance variables in Python

Question

Is there a built-in method in Python to get an array of all a class  instance variables  For example  if I have this code   class hi    def   init   self       self ii    foo      self kk    bar    Is there a way for me to do this    gt  gt  gt  mystery method hi    ii    kk     Edit  I originally had asked for class variables erroneously

User · Answer

Although not directly an answer to the OP question, there is a pretty sweet way of finding out what variables are in scope in a function. take a look at this code:

>>> def f(x, y):
    z = x**2 + y**2
    sqrt_z = z**.5
    return sqrt_z

>>> f.func_code.co_varnames
('x', 'y', 'z', 'sqrt_z')
>>>

The func_code attribute has all kinds of interesting things in it. It allows you todo some cool stuff. Here is an example of how I have have used this:

def exec_command(self, cmd, msg, sig):

    def message(msg):
        a = self.link.process(self.link.recieved_message(msg))
        self.exec_command(*a)

    def error(msg):
        self.printer.printInfo(msg)

    def set_usrlist(msg):
        self.client.connected_users = msg

    def chatmessage(msg):
        self.printer.printInfo(msg)

    if not locals().has_key(cmd): return
    cmd = locals()[cmd]

    try:
        if 'sig' in cmd.func_code.co_varnames and \
                       'msg' in cmd.func_code.co_varnames: 
            cmd(msg, sig)
        elif 'msg' in cmd.func_code.co_varnames: 
            cmd(msg)
        else:
            cmd()
    except Exception, e:
        print '\n-----------ERROR-----------'
        print 'error: ', e
        print 'Error proccessing: ', cmd.__name__
        print 'Message: ', msg
        print 'Sig: ', sig
        print '-----------ERROR-----------\n'

User · Answer

built on dmark s answer to get the following  which is useful if you want the equiv of sprintf and hopefully will help someone     def sprint object       result          for i in  v for v in dir object  if not callable getattr object  v   and v 0                   result      n s     i   str getattr object  i           return result

User · Answer

You can also test if an object has a specific variable with    gt  gt  gt  hi obj   hi    gt  gt  gt  hasattr hi obj   some attribute

User · Answer

Suggest   gt  gt  gt  print vars   doc   vars  object   - gt  dictionary  Without arguments  equivalent to locals    With an argument  equivalent to object   dict      In otherwords  it essentially just wraps   dict

User · Answer

Use vars    class Foo object       def   init   self           self a   1         self b   2  vars Foo        gt    a   1   b   2  vars Foo    keys       gt    a    b

User · Answer

Both the Vars   and dict methods will work for the example the OP posted  but they won t work for  loosely  defined objects like   class foo    a    foo    b    bar    To print all non-callable attributes  you can use the following function   def printVars object       for i in  v for v in dir object  if not callable getattr object v             print   n s     i         exec  print object  s n n     i

User · Answer

You normally can t get instance attributes given just a class  at least not without instantiating the class  You can get instance attributes given an instance  though  or class attributes given a class  See the  inspect  module  You can t get a list of instance attributes because instances really can have anything as attribute  and -- as in your example -- the normal way to create them is to just assign to them in the   init   method   An exception is if your class uses slots  which is a fixed list of attributes that the class allows instances to have  Slots are explained in http   www python org 2 2 3 descrintro html  but there are various pitfalls with slots  they affect memory layout  so multiple inheritance may be problematic  and inheritance in general has to take slots into account  too

User · Answer

Sometimes you want to filter the list based on public private vars   E g   def pub vars self          Gives the variable names of our instance we want to expose             return  k for k in vars self  if not k startswith

User · Answer

Every object has a   dict   variable containing all the variables and its values in it   Try this   gt  gt  gt  hi obj   hi    gt  gt  gt  hi obj   dict   keys

User · Answer

You will need to first  examine the class  next  examine the bytecode for functions  then  copy the bytecode  and finally  use the   code   co varnames  This is tricky because some classes create their methods using constructors like those in the types module  I will provide code for it on GitHub

User · Answer

Your example shows  instance variables    not really class variables   Look in hi obj   class     dict   items   for the class variables  along with other other class members like member functions and the containing module   class Hi  object        class var     23   skidoo      class variable     def   init    self            self ii    foo    instance variable         self jj    bar    Class variables are shared by all instances of the class

[python] How to get instance variables in Python?

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