Finding what methods a Python object has

Question

Given a Python object of any kind  is there an easy way to get the list of all methods that this object has   Or   if this is not possible  is there at least an easy way to check if it has a particular method other than simply checking if an error occurs when the method is called

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You can make use of dir   which is pre-defined in Python  import module name dir module name   You can also pass an object to dir   as dir object name   If the object is an object of a pre-defined class such as int  str  etc  it displays the methods in it  you may know those methods as built in functions   If that object is created for a user-defined class  it displays all the methods given in that class

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Open a Bash shell  Ctrl   Alt   T on Ubuntu   Start a Python  3 shell in it  Create an object to observe the methods of  Just add a dot after it and press Tab twice and you ll see something like this  user note    python3 Python 3 4 3  default  Nov 17 2016  01 08 31   GCC 4 8 4  on linux Type  quot help quot    quot copyright quot    quot credits quot  or  quot license quot  for more information   gt  gt  gt  import readline  gt  gt  gt  readline parse and bind  quot tab  complete quot    gt  gt  gt  s    quot Any object  Now it s a string quot   gt  gt  gt  s    here tab should be pressed twice s   add              s   rmod             s istitle  s   class            s   rmul             s isupper  s   contains         s   setattr          s join  s   delattr          s   sizeof           s ljust  s   dir              s   str              s lower  s   doc              s   subclasshook     s lstrip  s   eq               s capitalize         s maketrans  s   format           s casefold           s partition  s   ge               s center             s replace  s   getattribute     s count              s rfind  s   getitem          s encode             s rindex  s   getnewargs       s endswith           s rjust  s   gt               s expandtabs         s rpartition  s   hash             s find               s rsplit  s   init             s format             s rstrip  s   iter             s format map         s split  s   le               s index              s splitlines  s   len              s isalnum            s startswith  s   lt               s isalpha            s strip  s   mod              s isdecimal          s swapcase  s   mul              s isdigit            s title  s   ne               s isidentifier       s translate  s   new              s islower            s upper  s   reduce           s isnumeric          s zfill  s   reduce ex        s isprintable  s   repr             s isspace

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The simplest way to get a list of methods of any object is to use the help   command   help object   It will list out all the available important methods associated with that object  For example  help str

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There is no reliable way to list all object s methods  dir object  is usually useful  but in some cases it may not list all methods  According to dir   documentation   With an argument  attempt to return a list of valid attributes for that object    Checking that method exists can be done by callable getattr object  method   as already mentioned there

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is there at least an easy way to check if it has a particular method other than simply checking if an error occurs when the method is called  While  quot Easier to ask for forgiveness than permission quot  is certainly the Pythonic way  you may be looking for  d   foo   bar    spam   eggs   if  get  in dir d       d get  foo     OUT   bar

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If you are  for instance  using shell plus you can use this instead    gt  gt  MyObject     that way  with the      just after your object  it ll show you all the attributes methods the class has

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On top of the more direct answers  I d be remiss if I didn t mention IPython  Hit Tab to see the available methods  with autocompletion  And once you ve found a method  try  help object method   to see the pydocs  method signature  etc  Ahh    REPL

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I believe that you want something like this   a list of attributes from an object  The built-in function dir   can do this job  Taken from help dir  output on your Python shell   dir      dir  object   - gt  list of strings  If called without an argument  return the names in the current scope  Else  return an alphabetized list of names comprising  some of  the attributes of the given object  and of attributes reachable from it  If the object supplies a method named   dir    it will be used  otherwise the default dir   logic is used and returns   for a module object  the module s attributes  for a class object   its attributes  and recursively the attributes of its bases  for any other object  its attributes  its class s attributes  and recursively the attributes of its class s base classes    For example    python Python 2 7 6  default  Jun 22 2015  17 58 13   GCC 4 8 2  on linux2 Type  quot help quot    quot copyright quot    quot credits quot  or  quot license quot  for more information    gt  gt  gt  a    quot I am a string quot   gt  gt  gt   gt  gt  gt  type a   lt class  str  gt   gt  gt  gt   gt  gt  gt  dir a      add        class        contains        delattr        doc        eq        format        ge        getattribute        getitem        getnewargs        getslice        gt        hash        init        le        len        lt        mod        mul        ne        new        reduce        reduce ex        repr        rmod        rmul        setattr        sizeof        str        subclasshook       formatter field name split     formatter parser    capitalize    center    count    decode    encode    endswith    expandtabs    find    format    index    isalnum    isalpha    isdigit    islower    isspace    istitle    isupper    join    ljust    lower    lstrip    partition    replace    rfind    rindex    rjust    rpartition    rsplit    rstrip    split    splitlines    startswith    strip    swapcase    title    translate    upper    zfill

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Suppose we have a Python obj  Then to see all the methods it has  including those surrounded by     magic methods   print dir obj    To see only methods available via infix  dot  notation  one would   m for m in dir obj  if not m startswith

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I have done the following function  get object functions   which receives an object  object   as its argument  and returns a list  functions  containing all of the methods  including static and class methods  defined in the object s class  def get object functions object        functions    attr name                  for attr name in dir object                    if str type getattr object                                        attr name    in   quot  lt class  function  gt  quot                                                          quot  lt class  method  gt  quot        return functions  Well  it just checks if the string representation of the type of a class  attribute equals  quot  lt class  function  gt  quot  or  quot  lt class  method  gt  quot  and then includes that attribute in the functions list if that s True   Demo class Person      def   init   self  name  age           self name   name         self age   age      def introduce self           print f My name is  self name          staticmethod     def say hi            print  hi         classmethod     def reproduce cls  name           return cls name  0    person   Person  Rafael   27  print get object functions person     Output     init      introduce    reproduce    say hi    For a cleaner version of the code  https   github com revliscano utilities blob master get object functions object functions getter py

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If you specifically want methods  you should use inspect ismethod   For method names   import inspect method names    attr for attr in dir self  if inspect ismethod getattr self  attr      For the methods themselves   import inspect methods    member for member in  getattr self  attr  for attr in dir self   if inspect ismethod member     Sometimes inspect isroutine can be useful too  for built-ins  C extensions  Cython without the  binding  compiler directive

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The simplest method is to use dir objectname   It will display all the methods available for that object  Cool trick

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In order to search for a specific method in a whole module  for method in dir module      if  keyword of methode  in method      print method  end   n

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One can create a getAttrs function that will return an object s callable property names  def getAttrs object     return filter lambda m  callable getattr object  m    dir object    print getAttrs  Foo bar  split         That d return      add        class        contains        delattr        delitem         delslice        eq        format        ge        getattribute          getitem        getslice        gt        iadd        imul        init          iter        le        len        lt        mul        ne        new          reduce        reduce ex        repr        reversed        rmul          setattr        setitem        setslice        sizeof        str          subclasshook      append    count    extend    index    insert    pop      remove    reverse    sort

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To check if it has a particular method   hasattr object  method

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Take a list as an object  obj        list filter lambda x callable getattr obj x   obj   dir        You get       add         class         contains         delattr         delitem         dir         eq         format         ge         getattribute         getitem         gt         iadd         imul         init         init subclass         iter         le         len         lt         mul         ne         new         reduce         reduce ex         repr         reversed         rmul         setattr         setitem         sizeof         str         subclasshook       append     clear     copy     count     extend     index     insert     pop     remove     reverse     sort

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The problem with all methods indicated here is that you can t be sure that a method doesn t exist  In Python you can intercept the dot calling through   getattr   and   getattribute    making it possible to create method  quot at runtime quot  Example  class MoreMethod object       def some method self  x           return x     def   getattr   self   args           return lambda x  x 2  If you execute it  you can call non-existing methods in the object dictionary     gt  gt  gt  o   MoreMethod    gt  gt  gt  o some method 5  5  gt  gt  gt  dir o      class        delattr        dict        doc        format        getattr        getattribute        hash        init        module        new        reduce        reduce ex        repr        setattr        sizeof        str        subclasshook        weakref      some method    gt  gt  gt  o i dont care of the name 5  10  And it s why you use the Easier to ask for forgiveness than permission paradigms in Python

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For many objects  you can use this code  replacing  object  with the object you re interested in  object methods    method name for method name in dir object                    if callable getattr object  method name     I discovered it at diveintopython net  now archived   Hopefully  that should provide some further detail  If you get an AttributeError  you can use this instead  getattr  is intolerant of pandas style python3 6 abstract virtual sub-classes   This code does the same as above and ignores exceptions  import pandas as pd df   pd DataFrame   10  20  30    100  200  300                      columns   foo    bar    baz    def get methods object  spacing 20     methodList        for method name in dir object       try          if callable getattr object  method name                methodList append str method name       except          methodList append str method name     processFunc    lambda s      join s split     or  lambda s  s    for method in methodList      try          print str method ljust spacing                         processFunc str getattr object  method    doc    0 90        except          print method ljust spacing            getattr   failed    get methods df  foo

User · Answer

You can use the built in dir   function to get a list of all the attributes a module has   Try this at the command line to see how it works    gt  gt  gt  import moduleName  gt  gt  gt  dir moduleName    Also  you can use the hasattr module name   attr name   function to find out if a module has a specific attribute   See the Guide to Python introspection for more information

User · Answer

import moduleName for x in dir moduleName       print x   This should work

[python] Finding what methods a Python object has

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