I'm trying to set some booleans based on whether or not an object has attributes:
try:
att1 = myobj.att1
att2 = myobj.att2
att3 = myobj.att3
except AttributeError:
pass
However, if att1 is not present and throws an AttributeError, it won't try the other two. Must I loop (is there no way to do it in one try statement?)
Thanks!
why not just do :
your_boolean = hasattr(obj, att1) or hasattr(obj, att2) or hasattr(obj, att3)
No need for a try statement here. For example:
myobj = 10
names = ['att1', 'att2', 'att3', 'real']
results = dict((name, getattr(myobj, name, None)) for name in names)
#{'real': 10, 'att3': None, 'att2': None, 'att1': None}
Are you using this only to check whether some object has attributes? If so, use the built-in function hasattr (which in fact does the same test as you have implemented manually anyway.
Otherwise, you must loop.
If you think about the structure of the code, what you are really wanting is three try...except blocks -- after all, if exceptions returned flow to where they were raised after being processed, they wouldn't be very exceptional!
It would be pretty easy to write a loop, though:
atts = []
for attr in ("att1", "att2", "att3"):
try:
attrs.append(getattr(myobj, attr))
except AttributeError:
attrs.append[None]
att1, att2, att3 = atts
If you really want the attributes as local variables, you could even do:
for attr in ("att1", "att2", "att3"):
try:
locals()[attr] = getattr(myobj, attr)
except AttributeError:
pass
Considering there is 2*2*2 possible existence combinations, why not have set?
set(attr for attr in ('att%i' for i in range(1,4)) if obj.hasattr(attr))
I think this also works:
try:
(var1 and var2)
except NameError:
...
It will test all variables before making a decision.
