Introspection to get decorator names on a method?

Question

I am trying to figure out how to get the names of all decorators on a method. I can already get the method name and docstring, but cannot figure out how to get a list of decorators.

Answer 1

I'm surprised that this question is so old and no one has taken the time to add the actual introspective way to do this, so here it is:

The code you want to inspect...

def template(func):     def wrapper(*args, **kwargs):         return func(*args, **kwargs)     return wrapper  baz = template che = template  class Foo(object):     @baz     @che     def bar(self):         pass 

Now you can inspect the above Foo class with something like this...

import ast import inspect  def get_decorators(cls):     target = cls     decorators = {}      def visit_FunctionDef(node):         decorators[node.name] = []         for n in node.decorator_list:             name = ''             if isinstance(n, ast.Call):                 name = n.func.attr if isinstance(n.func, ast.Attribute) else n.func.id             else:                 name = n.attr if isinstance(n, ast.Attribute) else n.id              decorators[node.name].append(name)      node_iter = ast.NodeVisitor()     node_iter.visit_FunctionDef = visit_FunctionDef     node_iter.visit(ast.parse(inspect.getsource(target)))     return decorators  print get_decorators(Foo) 

That should print something like this...

{'bar': ['baz', 'che']} 

or at least it did when I tested this with Python 2.7.9 real quick :)

Answer 2

If you can change the way you call the decorators from

class Foo(object):     @many     @decorators     @here     def bar(self):         pass 

to

class Foo(object):     @register(many,decos,here)     def bar(self):         pass 

then you could register the decorators this way:

def register(*decorators):     def register_wrapper(func):         for deco in decorators[::-1]:             func=deco(func)         func._decorators=decorators                 return func     return register_wrapper 

For example:

def many(f):     def wrapper(*args,**kwds):         return f(*args,**kwds)     return wrapper  decos = here = many  class Foo(object):     @register(many,decos,here)     def bar(self):         pass  foo=Foo() 

Here we access the tuple of decorators:

print(foo.bar._decorators) # (<function many at 0xb76d9d14>, <function decos at 0xb76d9d4c>, <function here at 0xb76d9d84>) 

Here we print just the names of the decorators:

print([d.func_name for d in foo.bar._decorators]) # ['many', 'decos', 'here']