Python Style Guide Questions

[Steven D'Aprano]

On Thu, 15 Jan 2009 22:13:06 -0800, koranthala wrote:

> Hi,
>    Which is more advisable?
> import x
> b = x.a
>              or
> from x import a
> b = a
> 
>    I read in Learning Python that it is always better to use the
> former 

Perhaps not "always", but often.

> - especially since namespace wont be dirtied. But, doing that
> with PEP 8 together causes my code to look rather cluttered. Reason
> being that - PEP 8 suggests that have max line length = 79 chars. So my
> code mostly looks like this:
> class x:
>      def y():
>           try:
>               if test:
>                   obj.filename = str(os.path.basename
> (obj1.find_next_element().\
>                                               get_file_path()))
>                   obj.modify_time = obj.filename.find_created_time()
> +  \
>                                               datetime.timedelta
> (seconds=time.find_time())


A few ideas for you:


There is rarely enough performance benefit from squashing as much as 
possible into a single expression to make up for the loss of readability. 
Use temporary values to aid comprehension and readability.


class X:
    def y(self):
        try:
            if test:
                path = obj1.find_next_element().get_file_path()
                obj.filename = str(os.path.basename(path))
                ctime = obj.filename.find_created_time()
                offset = datetime.timedelta(seconds=time.find_time())
                obj.modify_time = ctime + offset


Alternatively, don't nest so much.

class X:
    def _y(self):
        path = obj1.find_next_element().get_file_path()
        obj.filename = str(os.path.basename(path))
        ctime = obj.filename.find_created_time()
        offset = datetime.timedelta(seconds=time.find_time())
        obj.modify_time = ctime + offset
    def y(self):
        try:
            if test:
                self._y()


Last but not least, Python now does automatic line continuations inside 
open brackets. You can use this to eliminate many backslashes.

class X:
    def y(self):
        try:
            if test:
                obj.filename = str(
                    os.path.basename(
                    obj1.find_next_element().get_file_path()
                    ))
                obj.modify_time = \
                    obj.filename.find_created_time() + \
                    datetime.timedelta(seconds=time.find_time())



Hope this helps.


-- 
Steven