Re: [Tutor] hasattr()

[Matthew Ngaha]

Thank you xDog and Steven. The whole assignment makes a lot of sense now
after your explanations of what hasattr is doing. Thanks
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Re: [Tutor] hasattr()

[Steven D'Aprano]

On 14/10/12 05:29, Matthew Ngaha wrote:

im trying to understand this hasattr function. i am supposed to pass in an
object and an attribute name into its parametres... so im trying to get it
to return True. Here's a quick test

class Test:
 def __init__(self):
self.att = "testing"



Okay, so you have a class that defines an attribute named "att".


e = Test()
hasattr(e, e.att)

False


Break this down step by step. First you create an instance, "e", with an
attribute e.att. Python evaluates e.att to get the string "testing", then
looks up hasattr(e, "testing"). Does e have an attribute called "testing"?
No. So it returns False.



hasattr(e, "testing")

False


Same here, except that you bypass the evaluation of e.att and enter the
string "testing" manually.

What you need to pass to hasattr (as well as its friends getattr and
setattr) is the *name* of the attribute, not its contents:


hasattr(e, "att")

will return True.



--
Steven
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Re: [Tutor] hasattr()

[xDog Walker]

On Saturday 2012 October 13 11:29, Matthew Ngaha wrote:
> >>> hasattr(e, e.att)
>
> False

>>> hasattr(e, "att")
True

hasattr wants the second parameter to be a string.
You gave it a string.
The string you gave it was "Testing".

-- 
Yonder nor sorghum stenches shut ladle gulls stopper torque wet 
strainers.

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