Re: Newbie: How can I use a string value for a keyword argument?

On Feb 25, 10:42 pm, Doug Morse <mo...@xxxxxxxxx> wrote:
Hi,

My apologies for troubling for what is probably an easy question... it's just
that can't seem to find an answer to this anywhere (Googling, pydocs, etc.)...

I have a class method, MyClass.foo(), that takes keyword arguments. For
example, I can say:

x = MyClass()
x.foo(trials=32)

Works just fine.

What I need to be able to do is call foo() with a string value specifying the
keyword (or both the keyword and value would be fine), something along the
lines of:

x = MyClass()
y = 'trials=32'
x.foo(y) # doesn't work

or

x.MyClass()
y = 'trials'
x.foo(y = 32) # does the "wrong" thing

Surely there's some way to use a string's value as the key for making a method
call with a keyword argument?

Just for completeness, my goal is simply to read a bunch of key/value pairs
from an INI file (using ConfigObj) and then use those key/value pairs to set a
(3rd party) object's parameters, which must be done with a call along the
lines of "instance.set(key=value)". Obviously, I could create a huge if..elif
statement along the lines of "if y = 'trials': x.foo(trials=32); elif y =
'speed': x.foo(speed=12);" etc., but then the statement has to be maintained
every time a new parameter is added/changed etc. Plus, such a solution seems
to me grossly inelegant and un-Pythonic.


I'm not quite sure what foo() is really supposed to do ... however the
built-in function setattr is your friend. Assuming that ini_dict
contains what you have scraped out of your .ini file, you can do:
x = MyCLass()
for key, value in ini_dict.items():
setattr(x, key, value)
You may prefer (I would) to do it inside the class, and maybe do some
checking/validation:
class MyClass(object):
def load(self, adict):
for k, v in adict.items():
# do checking here
setattr(self, k, v)
# much later
x = MyClass()
x.load(ini_dict)

HTH,
John
.

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