Can someone help please

rantingrick rantingrick at gmail.com
Fri Jul 22 22:04:32 CEST 2011


On Jul 21, 12:02 pm, Gary <woody... at sky.com> wrote:

--------------------------------------------------
> total = ' '
> os.chdir('/home/woodygar/Desktop/Docs')
> for i in os.listdir('.'):
--------------------------------------------------
"i" was a bad local var choice here! i and x are typically reserved to
represent integer indexes in local loop scope whilst iterating over a
container object. Likewise y and z are meant to represent the next
levels of indexes. However when looping over a list of strings use
something more appropriate like:

for filename in os.listdir('.'):
    do_something_with(filename)

--------------------------------------------------
>    if '.txt' in i:
--------------------------------------------------

No, no, don't do that! Do if str.endswith('.txt') instead. Or use the
os.path methods.

--------------------------------------------------
>      f = open(i, 'r')
>      total += f.read()
>      f.close()
--------------------------------------------------

Two bad things happening here;

(1.) Need to catch exceptions.

try:
    f = open(i, 'r')
    total += f.read()
except IOERROR:
    freak_out()
else:
    f.close()

(2.) NEVER concatenate a string with += in a loop! Instead load the
strings into a list and then use ''.join(lst) method on the list.

>>> filetext = """\
This is line one
this is line two

this is line four\
"""
>>> lst = []
>>> for line in filetext.splitlines():
	lst.append(line)
>>> lst
['This is line one', 'this is line two', '', 'this is line four']
>>> '\n'.join(lst)
'This is line one\nthis is line two\n\nthis is line four'
>>> print '\n'.join(lst)
This is line one
this is line two

this is line four
>>>


--------------------------------------------------
> message = """\
> Subject: %s
> %s
>
> """% (SUBJECT,total)
--------------------------------------------------

Use the new format spec over the old string interpolation if available
in your version of python.

MSG = """
Subject: {0}
{1}
"""
MSG.format(SUBJECT,total)





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