Include code snippet in org file - org-mode

Question

I'm wanting to use org mode to write a technical book. I'm looking for a way to insert existing code from external file into a babel code block that would give nice formatting when exporting to pdf.
For example
#+BEGIN_SRC python "./code/foo.py"
# insert_line (45,50)
#+END_SRC
would then give me the equivalent of the following from line 45 to 50 in foo.py
#+BEGIN_SRC python
def times_two(x):
y = x*2
return y
print times_two(5)
#+END_SRC
Is there anyway of doing this?

Answer 1

I think something like this could work:
#+include: "./code/foo.py" :lines "45-50"
Link to manual: http://orgmode.org/manual/Include-files.html

Answer 2

You can use a shell script to print the lines out with a :wrap header. For example, here I print lines 9-18 of the wos.py script. The shell script won't export if you set :exports too.
#+BEGIN_SRC sh :wrap src python :exports results
sed -n 9,18p wos.py
#+END_SRC
#+RESULTS:
#+BEGIN_src python
class HTTPSudsPreprocessor(urllib2.BaseHandler):
def __init__(self, SID):
self.SID = SID
def http_request(self, req):
req.add_header('cookie', 'SID="'+self.SID+'"')
return req
https_request = http_request
#+END_src
If you don't have sed, you can write a little python script that does the same thing. Just remember to shift the line numbers by one, and to set results to code.
#+BEGIN_SRC python :results code :exports results
with open("wos.py") as f:
print("".join(f.readlines()[8:17]))
#+END_SRC
#+RESULTS:
#+BEGIN_SRC python
class HTTPSudsPreprocessor(urllib2.BaseHandler):
def __init__(self, SID):
self.SID = SID
def http_request(self, req):
req.add_header('cookie', 'SID="'+self.SID+'"')
return req
https_request = http_request
#+END_SRC