[Tutor] problem reading script

[Martin A. Brown]

Greetings Lisi,

 : I am supposed to be looking at scripts on-line, reading them and 
 : making sure that I understand them. 

When you see an example that you don't understand, consider trying 
to do something similar in an interactive Python interpreter.  This 
is a simple way to learn in Python.

 : I think taht most of teh things I can't make more than a guess 
 : at, are modules taht I don't know, and I can mostly make them 
 : out.  But the unpaired double quotation mark, " , in the 
 : following has me stumped:

Look carefully.  It is not an unpaired double-quotation mark.  Are 
you using a monospaced font to read code?  If you are using a 
variable width font, you should change to monospaced.  Save yourself 
some future headache.  Really.  Use a monospaced font.

 : report['BzrLogTail'] = ''.join(bzr_log_tail)

Do you have a Python interpreter handy?  This is a fairly typical 
pythonic expression for concatenating elements of a list into a 
string.  Try the following in a python interpreter:

  >>> l = list()
  >>> l.append("a")
  >>> l.append("b")
  >>> l.append("c")
  >>> l
  ['a', 'b', 'c']
  >>> ''.join(l)
  'abc'

Now, you are probably wondering about that peculiar looking syntax 
for calling join() on a list.  This single quoted empty string '' is 
still a string, so it has methods that can be called on it.  Read up 
on methods available on strings [0] to get a better idea.  For other 
examples of using the string join() method, consider the following:

  >>> ':'.join(l)
  'a:b:c'

  >>> vampire = [ 'The','Deluxe','Transitive','Vampire' ]
  >>> ' '.join(vampire)
  'The Deluxe Transitive Vampire'

And, for something just a bit fancier, make a list of ints, using 
the function called range():

  >>> range(10)
  [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

Convert them to a list of strings:

  >>> [str(x) for x in range(10)]
  ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']

Now, concatenate them and separate with some spacedash!

  >>> visual_separator = ' -- '
  >>> visual_separator.join(str(x) for x in range(10))
  '0 -- 1 -- 2 -- 3 -- 4 -- 5 -- 6 -- 7 -- 8 -- 9'

With any luck, these examples help explain what you were reading.

-Martin

 [0] http://docs.python.org/dev/library/stdtypes.html#string-methods

-- 
Martin A. Brown
http://linux-ip.net/