try..except or type() or isinstance()?

[Manfred Lotz]

I have an object which I could initialize providind an int or a str. 

I am not sure which of the following is best to use 
 - try/except
 - if type(int)...
 - if isinstance(v, int)

Here a minimal example

def get_id(fromname):
    # do something with `fromname`
    return 0

def get_name(fromid):
    # do something with `fromid`
    return "something"

""" For O1, O2, O3: self.myid is int
                                        self.name is str
"""
class O1:
    def __init__(self, val):
        try:
            self.myid = int(val)
            self.name = get_name(self.myid)
        except:
            self.myid = get_id(val)
            self.name = val

class O2:
    def __init__(self, val):
        if type(val) == int:
            self.myid = val
            self.name = get_name(self.myid)
        else:
            self.myid = get_id(val)
            self.name = val

class O3:
    def __init__(self, val):
        if isinstance(val, int):
            self.myid = val
            self.name = get_name(self.myid)
        else:
            self.myid = get_id(val)
            self.name = val

-- 
Manfred