On 06/17/2013 05:17 PM, Jim Mooney wrote:
On 17 June 2013 11:30, Peter Otten <__pete...@web.de> wrote:
The help() function in the interactive interpreter is a good tool hunt for
help on features of functions and classes. For example:
I tripped on Python help a couple of times, since I'm used to
easy-living GUI help, so here is a bit of help on help. From the
Python command line it may be help(open), for instance, but only for
builtins -- things that don't need dot syntax. For methods, like
str.find(), that need dot syntax, it's help(str.find) not help(find);
or you can use your own defined string name, such as
help(your_big_string.find). Basically, Python help must be fed an
object. It's not like a GUI searchable help file.
And for a method you don't use the method call, so it's help(str.find)
not help(str.find()) I'm embarrassed to say that tripped me up a
couple of times, due to habit.
You can use the call version, if you want help on the return type. Of
course, you want to watch out for side effects; don't do this unless
you really want the method to be called.
For instance, you get help for open but not for close. Since you open
with a file handle such as fh = open('yourfile'), you must use
fh.close(), since close is a method of fh, and not a builtin. Since
python follows your lead and see the object fh, you can get help with
help(fh.close) as you named it, but not for help(close). I'm not sure
of the generic name Python wants for file, that would work like
help(str.find). I'll have to go find that. I tried 'file' but that
ain't it.
In Python 2.x
help(file.close)
In Python 3.x,
help(_io.TextIOWrapper.close)
or
help(sys.stdin.close)
But that 3.3 help text isn't right.
In 2.x, it starts:
Help on method_descriptor:
close(...)
close() -> None or (perhaps) an integer. Close the file.
Sets data attribute .closed to....
But in 3.3, it says:
Help on built-in function close:
close(...)
with no more explanation.
And if you want to be obtuse, just to see that python help Always
wants an object, even if you don't see it:
import builtins
help(builtins.open) works to get the
supercalifragilisticexpialidocoius genormous help file for open, which
tells you more things about open than you could possibly want to know
unless you are really Hardcore ;')
But it is not recommended as your primary method.
--
DaveA
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