Python function pointer

Question

I have a function name stored in a variable like this   myvar    mypackage mymodule myfunction    and I now want to call myfunction like this  myvar parameter1  parameter2    What s the easiest way to achieve this

User · Answer

modname  funcname   myvar rsplit      1  getattr sys modules modname   funcname  parameter1  parameter2

User · Answer

Why not store the function itself  myvar   mypackage mymodule myfunction is much cleaner

User · Answer

Easiest  eval myvar  parameter1  parameter2    You don t have a function  pointer    You have a function  name    While this works well  you will have a large number of folks telling you it s  insecure  or a  security risk

User · Answer

It s much nicer to be able to just store the function itself  since they re first-class objects in python   import mypackage  myfunc   mypackage mymodule myfunction myfunc parameter1  parameter2    But  if you have to import the package dynamically  then you can achieve this through   mypackage     import    mypackage   mymodule   getattr mypackage   mymodule   myfunction   getattr mymodule   myfunction    myfunction parameter1  parameter2    Bear in mind however  that all of that work applies to whatever scope you re currently in  If you don t persist them somehow  you can t count on them staying around if you leave the local scope

User · Answer

I ran into a similar problem while creating a library to handle authentication  I want the app owner using my library to be able to register a callback with the library for checking authorization against LDAP groups the authenticated person is in  The configuration is getting passed in as a config py file that gets imported and contains a dict with all the config parameters   I got this to work    gt  gt  gt  class MyClass object           def target func self               print  made it                   def   init   self config               self config   config             self config  funcname     getattr self self config  funcname                self config  funcname           gt  gt  gt  instance   MyClass   funcname   target func    made it    Is there a pythonic-er way to do this

User · Answer

eval compile myvar   lt str gt    eval    myargs   compile      eval   allows only a single statement  so that there can t be arbitrary commands after a call  or there will be a SyntaxError  Then a tiny bit of validation can at least constrain the expression to something in your power  like testing for  mypackage  to start

User · Answer

def f a b       return a b  xx    f  print eval   s  s  s    xx 2 3     OUTPUT   5

User · Answer

funcdict        mypackage mymodule myfunction   mypackage mymodule myfunction              funcdict myvar  parameter1  parameter2

[python] Python function pointer

Examples related to python

Examples related to function-pointers