About getattr()

[Jm lists]

Hello,

Since I can write the statement like:

>>print os.path.isdir.__doc__

Test whether a path is a directory

Why do I still need the getattr() func as below?

>>print getattr(os.path,"isdir").__doc__

Test whether a path is a directory

Thanks!

[Leif K-Brooks]

Jm lists wrote:

Since I can write the statement like:

>>>print os.path.isdir.__doc__

Test whether a path is a directory

Why do I still need the getattr() func as below?

>>>print getattr(os.path,"isdir").__doc__

Test whether a path is a directory

You don't. getattr() is only useful when the attribute name is
determined at runtime.

[Samuel Karl Peterson]

"Jm lists" <pr***********@gmail.comon Mon, 12 Feb 2007 12:36:10
+0800 didst step forth and proclaim thus:

Hello,

Since I can write the statement like:

>print os.path.isdir.__doc__

Test whether a path is a directory

Why do I still need the getattr() func as below?

>print getattr(os.path,"isdir").__doc__

Test whether a path is a directory

getattr lets you lookup an attribute given a string, so the attribute
wouldn't have to be hardcoded in your program, it could come from a
file, or from user input.

--
Sam Peterson
skpeterson At nospam ucdavis.edu
"if programmers were paid to remove code instead of adding it,
software would be much better" -- unknown

[Duncan Booth]

Leif K-Brooks <eu*****@ecritters.bizwrote:

>Why do I still need the getattr() func as below?

>>>>print getattr(os.path,"isdir").__doc__

Test whether a path is a directory

You don't.

Correct

getattr() is only useful when the attribute name is
determined at runtime.

getattr() is useful in at least 2 other situations:

maybe you know the attribute name in advance, but don't know whether the
object has that particular attribute, then the 3 argument form of getattr
could be appropriate:

print getattr(x, 'attr', 'some default')

or if the attribute name isn't a valid Python identifier:

print getattr(x, 'class')