redirecting web page
Hi, I am a newbie about python. Now I am modifying the tinyHTTPProxy to redirect a client's request to our company's webpage. I don't know how can I do this. What I want to do now is to modify the headers, but i still didn't figure out how to do it. Thank you very much -- http://mail.python.org/mailman/listinfo/python-list
Questions on "import" and "datetime"
Hi all, I have some questions on "import": 1."from datetime import datetime" works well. But I am confused why "import datetime.datetime" leads to importerror. "from xlrd import open_workbook" could be replaced by "from xlrd.open_workbook" without any problem. The only difference here is that if "from xlrd import open_workbook" is used we do not have to write "xlrd.open_workbook" in the following code but just "open_workbook". So my understanding of the difference is "from...import..." shortens the code (just like "using namespace std" in C++) but maybe leads to name clash. But what is the problem of datetime? 2.I am also comfused that "datetime.datetime" is a function but whithin "datetime.datetime" there are lots of other functions. So what is the type of "datetime.datetime" on earth? is it a function, or a class or a folder(library) here? Thanks very much in advance! Very looking forward to your answers. Best, Yunfei -- http://mail.python.org/mailman/listinfo/python-list
Re: Questions on "import" and "datetime"
On Monday, June 10, 2013 7:01:30 PM UTC+2, Zachary Ware wrote: > On Mon, Jun 10, 2013 at 10:37 AM, Yunfei Dai > wrote: > > > Hi all, > > > > Hi Yunfei, > > > > > > > > I have some questions on "import": > > > > > > 1."from datetime import datetime" works well. But I am confused why "import > > datetime.datetime" leads to importerror. "from xlrd import open_workbook" > > could be replaced by "from xlrd.open_workbook" without any problem. > > > > I assume you mean "import xlrd.open_workbook" here, as "from > > xlrd.open_workbook" would be a SyntaxError :) > > > > > The only difference here is that if "from xlrd import open_workbook" is > > used we do not have to write "xlrd.open_workbook" in the following code but > > just "open_workbook". So my understanding of the difference is > > "from...import..." shortens the code (just like "using namespace std" in > > C++) but maybe leads to name clash. > > > > "from ... import ..." imports an object from a module and assigns it > > to a local name that is the same as the name in the other module. In > > other words, the following two examples do the same thing: > > > > from foo import bar > > > > import foo;bar = foo.bar > > > > If foo.bar happens to be a module (module 'bar' in package 'foo'), you > > could also do this: > > > > import foo.bar as bar > > > > ...and that restriction is where your problem lies. > > > > > But what is the problem of datetime? > > > > I'm not familiar with xlrd, but I believe the difference between > > xlrd.open_workbook and datetime.datetime would be that > > xlrd.open_workbook is a module in a package, while datetime.datetime > > is a class in a module. 'from ... import ...' can import any object > > from the target module/package, and assign it to a local name. > > 'import ...' on the other hand can only import a module (you'll notice > > the ImportError you get when you try 'import datetime.datetime' is 'No > > module named datetime'. This particular example is a bit confusing > > due to there being a class in a module of the same name, but try > > 'import datetime.date' for a clearer message. > > > > > 2.I am also comfused that "datetime.datetime" is a function but whithin > > "datetime.datetime" there are lots of other functions. So what is the type > > of "datetime.datetime" on earth? is it a function, or a class or a > > folder(library) here? > > > > datetime.datetime is actually a type of type 'type' (as can be seen > > with 'import datetime;type(datetime.datetime)'). In Python 2, this > > means it is a new-style class (meaning it is a subclass of 'object'). > > In Python 3, it's just a class (since there are no longer old-style > > classes). > > > > > Thanks very much in advance! Very looking forward to your answers. > > > > > > Best, > > > Yunfei > > > > > > > I hope I have actually answered your question and not just muddied > > things further for you. You can of course ask again if I've made > > things worse :) > > > > -- Zach Hi Zach, Thanks so much for your quick, long and detailed reply and sorry for replying you late. It is really helpful for me understanding "import". Yunfei -- http://mail.python.org/mailman/listinfo/python-list
Re: Questions on "import" and "datetime"
On Monday, June 10, 2013 9:10:16 PM UTC+2, Dave Angel wrote: > On 06/10/2013 01:01 PM, Zachary Ware wrote: > > > On Mon, Jun 10, 2013 at 10:37 AM, Yunfei Dai > > wrote: > > >> Hi all, > > > > > > Hi Yunfei, > > > > > >> > > >> I have some questions on "import": > > >> > > >> 1."from datetime import datetime" works well. But I am confused why > >> "import datetime.datetime" leads to importerror. "from xlrd import > >> open_workbook" could be replaced by "from xlrd.open_workbook" without any > >> problem. > > > > > > > It's a historical flaw in datetime that the class has the same name as > > the module it's in. It should have been called class Datetime > > (according to pep 10, class names should be capitalized). If that were > > the case, it'd be clear that datetime.Datetime is a class. > > > > It would also be clearer that > > from datetime import Datetime > > > > creates an alias in the present global namespace for the > > datetime.Datetime class, as simply Datetime. > > > > This class has attributes that you can access, like Datetime.hour, and > > it has static methods like Datetime.fromTimeStamp(). > > And like all classes, it's "callable", meaning that you can create an > > instance by pretending it's a function: > > obj = Datetime(2013, 12, 1) > > > > But since it's not a module inside a package, you can't use the form: > > > > import datetime.Datetime > > > > Now, just interpret all the above with a lowercase "D" and the confusion > > becomes clearer. The compiler/interpreter doesn't care either way. > > > > > > > "from ... import ..." imports an object from a module and assigns it > > > to a local name that is the same as the name in the other module. In > > > other words, the following two examples do the same thing: > > > > > > from foo import bar > > > > > > import foo;bar = foo.bar > > > > > > If foo.bar happens to be a module (module 'bar' in package 'foo'), you > > > could also do this: > > > > > > import foo.bar as bar > > > > > > ...and that restriction is where your problem lies. > > > > > > > In other words, since datetime.datetime is a class, not a module, you > > can't just import it. > > > > > > > > > >> 2.I am also comfused that "datetime.datetime" is a function but whithin > >> "datetime.datetime" there are lots of other functions. So what is the type > >> of "datetime.datetime" on earth? is it a function, or a class or a > >> folder(library) here? > > > > > > > As I said before, datetime.datetime is a class, and the functions within > > it are called methods. > > > > You can see it all for yourself very easily. Use the __file__ attribute > > to locate the source for datetime module on your system. Here's what it > > looks like on mine: > > > > >>> import datetime > > >>> datetime.__file__ > > '/usr/local/lib/python3.3/datetime.py' > > > > Then you can go look at that file. For my copy, the datetime class > > begins at 1301. But you can just search for the following line: > > > > > > > > class datetime(date): > > > > HTH > > > > -- > > DaveA Thank you Dave for your reply! It is very helpful. -- http://mail.python.org/mailman/listinfo/python-list
