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Date: Mon, 18 Mar 2013 09:47:02 -0500
Subject: Re: How to automatically get the indent level from code?
From: Peng Yu <pengyu.ut@gmail.com>
To: Mark Shroyer <mshroyer@awaredigital.com>
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On Sun, Mar 17, 2013 at 1:23 AM, Mark Shroyer <mshroyer@awaredigital.com> wrote:
> I realize this isn't yet precisely what you're asking for, but look at the inspect and ast modules:
>
>     import ast, inspect
>
>     def indent_level():
>         lineno = inspect.currentframe().f_back.f_lineno
>
>         with open(__file__) as source_file:
>             tree = ast.parse(source_file.read(), filename=__file__)
>
>         for node in ast.walk(tree):
>             if hasattr(node, 'lineno') and node.lineno == lineno:
>                 return node.col_offset
>
>     def example_usage():
>         print("first indent_level() = {0}".format(indent_level()))
>         if True:
>             print("second indent_level() = {0}".format(indent_level()))
>
>     if __name__ == '__main__':
>         example_usage()
>
> The indent_level function above returns the textual column offset rather than the logical block level you're asking for, e.g.:
>
>     first indent_level() = 4
>     second indent_level() = 8
>
> But hopefully it's a start.

Thanks. I try to run it from stdin. Obviously, it does not work. The
problem is the stdin can not be read again. Is there a way to extend
the code that indentation can be computed even the code is from stdin?

~/linux/test/python/tricks/indent_level$ python - < main.py
Traceback (most recent call last):
  File "<stdin>", line 23, in <module>
  File "<stdin>", line 16, in example_usage
  File "<stdin>", line 8, in indent_level
IOError: [Errno 2] No such file or directory: '<stdin>'
~/linux/test/python/tricks/indent_level$ cat main.py
#!/usr/bin/env python

import ast, inspect

def indent_level():
  lineno = inspect.currentframe().f_back.f_lineno

  with open(__file__) as source_file:
    tree = ast.parse(source_file.read(), filename=__file__)

  for node in ast.walk(tree):
    if hasattr(node, 'lineno') and node.lineno == lineno:
      return node.col_offset

def example_usage():
  print indent_level()
  #print("first indent_level() = {0}".format(indent_level()))
  if True:
    print indent_level()
    #print("second indent_level() = {0}".format(indent_level()))

if __name__ == '__main__':
  example_usage()

-- 
Regards,
Peng