You could make two separate decorators that do what you want as illustrated directly below. Note the use of *args, **kwargs in the declaration of the wrapped() function which supports the decorated function having multiple arguments (which isn't really necessary for the example say() function, but is included for generality).
For similar reasons, the functools.wraps decorator is used to change the meta attributes of the wrapped function to be those of the one being decorated. This makes error messages and embedded function documentation (func.__doc__) be those of the decorated function instead of wrapped()'s.
from functools import wraps
def makebold(fn):
@wraps(fn)
def wrapped(*args, **kwargs):
return "<b>" + fn(*args, **kwargs) + "</b>"
return wrapped
def makeitalic(fn):
@wraps(fn)
def wrapped(*args, **kwargs):
return "<i>" + fn(*args, **kwargs) + "</i>"
return wrapped
@makebold
@makeitalic
def say():
return 'Hello'
print(say()) # -> <b><i>Hello</i></b>
As you can see there's a lot of duplicate code in these two decorators. Given this similarity it would be better for you to instead make a generic one that was actually a decorator factory—in other words, a decorator function that makes other decorators. That way there would be less code repetition—and allow the DRY principle to be followed.
def html_deco(tag):
def decorator(fn):
@wraps(fn)
def wrapped(*args, **kwargs):
return '<%s>' % tag + fn(*args, **kwargs) + '</%s>' % tag
return wrapped
return decorator
@html_deco('b')
@html_deco('i')
def greet(whom=''):
return 'Hello' + (' ' + whom) if whom else ''
print(greet('world')) # -> <b><i>Hello world</i></b>
To make the code more readable, you can assign a more descriptive name to the factory-generated decorators:
makebold = html_deco('b')
makeitalic = html_deco('i')
@makebold
@makeitalic
def greet(whom=''):
return 'Hello' + (' ' + whom) if whom else ''
print(greet('world')) # -> <b><i>Hello world</i></b>
or even combine them like this:
makebolditalic = lambda fn: makebold(makeitalic(fn))
@makebolditalic
def greet(whom=''):
return 'Hello' + (' ' + whom) if whom else ''
print(greet('world')) # -> <b><i>Hello world</i></b>
While the above examples do all work, the code generated involves a fair amount of overhead in the form of extraneous function calls when multiple decorators are applied at once. This may not matter, depending the exact usage (which might be I/O-bound, for instance).
If speed of the decorated function is important, the overhead can be kept to a single extra function call by writing a slightly different decorator factory-function which implements adding all the tags at once, so it can generate code that avoids the addtional function calls incurred by using separate decorators for each tag.
This requires more code in the decorator itself, but this only runs when it's being applied to function definitions, not later when they themselves are called. This also applies when creating more readable names by using lambda functions as previously illustrated. Sample:
def multi_html_deco(*tags):
start_tags, end_tags = [], []
for tag in tags:
start_tags.append('<%s>' % tag)
end_tags.append('</%s>' % tag)
start_tags = ''.join(start_tags)
end_tags = ''.join(reversed(end_tags))
def decorator(fn):
@wraps(fn)
def wrapped(*args, **kwargs):
return start_tags + fn(*args, **kwargs) + end_tags
return wrapped
return decorator
makebolditalic = multi_html_deco('b', 'i')
@makebolditalic
def greet(whom=''):
return 'Hello' + (' ' + whom) if whom else ''
print(greet('world')) # -> <b><i>Hello world</i></b>