why does "help(import)" not work?
Robert P. J. Day
i'm sure there's a painfully obvious answer to this, but is there a
reason i can't do:
>>> help(import)
File "<stdin>", line 1
help(import)
^
SyntaxError: invalid syntax
>>>
on the other hand, i can certainly go into "help()" and type
"import" to get that help. it seems counter-intuitive to have the
first variation fail but the second succeed.
what is the rule for this in python3?
rday
--
========================================================================
Robert P. J. Day Waterloo, Ontario, CANADA
Linux Consulting, Training and Kernel Pedantry.
Web page: http://crashcourse.ca
Twitter: http://twitter.com/rpjday
========================================================================
Simon Brunning
>
> i'm sure there's a painfully obvious answer to this, but is there a
> reason i can't do:
>
>>>> help(import)
> File "<stdin>", line 1
> help(import)
> ^
> SyntaxError: invalid syntax
import is a keyword, not an object.
--
Cheers,
Simon B.
Diez B. Roggisch
> i'm sure there's a painfully obvious answer to this, but is there a
> reason i can't do:
>
>>>> help(import)
> File "<stdin>", line 1
> help(import)
> ^
> SyntaxError: invalid syntax
>
> on the other hand, i can certainly go into "help()" and type
> "import" to get that help. it seems counter-intuitive to have the
> first variation fail but the second succeed.
>
> what is the rule for this in python3?
import is a keyword, so the parser can't comprehend the expression you
created. In the same way it can't do it for
help(class)
or
help(def)
or any other keyword.
Diez
Chris Rebert
> i'm sure there's a painfully obvious answer to this, but is there a
> reason i can't do:
>
>>>> help(import)
> File "<stdin>", line 1
> help(import)
> ^
> SyntaxError: invalid syntax
>>>>
>
> on the other hand, i can certainly go into "help()" and type
> "import" to get that help. it seems counter-intuitive to have the
> first variation fail but the second succeed.
>
> what is the rule for this in python3?
"Special cases aren't special enough to break the rules."
-- Zen of Python (http://www.python.org/dev/peps/pep-0020/)
It would take a hideous kludge to make help(import) work.
Cheers,
Chris
--
http://blog.rebertia.com
Bruno Desthuilliers
> i'm sure there's a painfully obvious answer to this, but is there a
> reason i can't do:
>
>>>> help(import)
Yes, there's a very painfully obvious reason : 'import' is a statement,
'help' is a function, and you can't (syntactically) pass a statement as
an argument to function !-)
> File "<stdin>", line 1
> help(import)
> ^
> SyntaxError: invalid syntax
>
> on the other hand, i can certainly go into "help()" and type
> "import" to get that help. it seems counter-intuitive to have the
> first variation fail but the second succeed.
Would you find it more "intuitive" to have different syntactic rules for
the interactive shell ?-)
FWIW, the way to get help on a statement (or on a non-already defined
name) is to pass a string to help, ie:
help("import")
HTH
Brian Quinlan
help() is just a regular function that must be called with correct
Python syntax and the import keyword is not allowed in an argument list.
The correct syntax is:
help('import')
Cheers,
Brian
On 6 Nov 2009, at 20:56, Robert P. J. Day wrote:
>
> i'm sure there's a painfully obvious answer to this, but is there a
> reason i can't do:
>
>>>> help(import)
> File "<stdin>", line 1
> help(import)
> ^
> SyntaxError: invalid syntax
>>>>
>
> on the other hand, i can certainly go into "help()" and type
> "import" to get that help. it seems counter-intuitive to have the
> first variation fail but the second succeed.
>
> what is the rule for this in python3?
>
> rday
> --
>
>
> =
> =
> ======================================================================
> Robert P. J. Day Waterloo, Ontario,
> CANADA
>
> Linux Consulting, Training and Kernel Pedantry.
>
> Web page: http://crashcourse.ca
> Twitter: http://twitter.com/rpjday
> =
> =
> ======================================================================
Robert P. J. Day
> On Fri, Nov 6, 2009 at 1:56 AM, Robert P. J. Day <rpj...@crashcourse.ca> wrote:
> > i'm sure there's a painfully obvious answer to this, but is there a
> > reason i can't do:
> >
> >>>> help(import)
> > File "<stdin>", line 1
> > help(import)
> > ^
> > SyntaxError: invalid syntax
> >>>>
> It would take a hideous kludge to make help(import) work.
>
> Cheers,
> Chris
um ... ok, i'll take your word for it, but is there at least a
generalizable pattern for what is directly help()able and what isn't?
rday
--
========================================================================
Robert P. J. Day
> Hi Robert,
>
> help() is just a regular function that must be called with correct
> Python syntax and the import keyword is not allowed in an argument
> list.
>
> The correct syntax is:
> help('import')
ah, ok, now it makes sense. so python3 just lets me be sloppy about
it, as in:
>>> help(print)
got it.
Chris Rebert
> On Fri, 6 Nov 2009, Chris Rebert wrote:
>
>> On Fri, Nov 6, 2009 at 1:56 AM, Robert P. J. Day <rpj...@crashcourse.ca> wrote:
>> > i'm sure there's a painfully obvious answer to this, but is there a
>> > reason i can't do:
>> >
>> >>>> help(import)
>> > File "<stdin>", line 1
>> > help(import)
>> > ^
>> > SyntaxError: invalid syntax
>> >>>>
>
>> It would take a hideous kludge to make help(import) work.
>
> generalizable pattern for what is directly help()able and what isn't?
Language keywords aren't help()-able:
http://docs.python.org/reference/lexical_analysis.html#keywords
Neither are punctuation/operators (see other sections on same webpage).
help() is run-of-the-mill function, no different than any other, is
not treated specially, and doesn't perform magic.
You can't pass raw syntax elements to functions (whether the functions
are built-in or user-defined).
Robert P. J. Day
> On Fri, 6 Nov 2009, Chris Rebert wrote:
>
> > On Fri, Nov 6, 2009 at 1:56 AM, Robert P. J. Day <rpj...@crashcourse.ca> wrote:
> > > i'm sure there's a painfully obvious answer to this, but is there a
> > > reason i can't do:
> > >
> > >>>> help(import)
> > > File "<stdin>", line 1
> > > help(import)
> > > ^
> > > SyntaxError: invalid syntax
> > >>>>
>
> > It would take a hideous kludge to make help(import) work.
> >
> > Cheers,
> > Chris
>
> um ... ok, i'll take your word for it, but is there at least a
> generalizable pattern for what is directly help()able and what
> isn't?
never mind, i was just educated on the proper usage of help(). i
*knew* i was going to embarrass myself when i asked that. :-P back
to reading.
Simon Brunning
> um ... ok, i'll take your word for it, but is there at least a
> generalizable pattern for what is directly help()able and what isn't?
If it's an object (or to be precise, a name bound to an object), it's
helpable. If it's a keyword, it's not - and in fact can't be, since as
you've found, it's a syntax error - so you fall back to passing a
string.
--
Cheers,
Simon B.
Simon Brunning
> it, as in:
print is a function in Python 3, so that's fine. In Python 2, that
would also be a syntax error.
--
Cheers,
Simon B.
Paul Rudin
> On Fri, 6 Nov 2009, Brian Quinlan wrote:
>
>> Hi Robert,
>>
>> help() is just a regular function that must be called with correct
>> Python syntax and the import keyword is not allowed in an argument
>> list.
>>
>> The correct syntax is:
>> help('import')
>
> ah, ok, now it makes sense. so python3 just lets me be sloppy about
> it, as in:
>
> >>> help(print)
>
> got it.
In python 3 print is a function.
Sion Arrowsmith
>On Fri, 6 Nov 2009, Brian Quinlan wrote:
>> The correct syntax is:
>> help('import')
>
> ah, ok, now it makes sense. so python3 just lets me be sloppy about
>it, as in:
>
> >>> help(print)
No, "print" is a function in python3, not a statement as it is in
earlier versions. There's nothing sloppy about it, and nothing in
help has changed from 2 to 3: if it's a language keyword, you need
to pass help it's name; if it's a function or a class, you can pass
help the object itself.
--
\S
under construction
Bruno Desthuilliers
> On Fri, Nov 6, 2009 at 2:28 AM, Robert P. J. Day <rpj...@crashcourse.ca> wrote:
>
>> um ... ok, i'll take your word for it, but is there at least a
>> generalizable pattern for what is directly help()able and what isn't?
>
> Language keywords aren't help()-able:
> http://docs.python.org/reference/lexical_analysis.html#keywords
> Neither are punctuation/operators (see other sections on same webpage).
Ever tried help("import") or help("if") or help("+") ?
Chris Rebert
help()-able in this context meaning you can drop the quotes and not
get a syntax error.