Exercise: Eliminate Empty/Comment-Only Lines

Write a program distill.py that takes a filename from the commandline.

• Open that file for reading

• Output (to stdout) every line that …

  • … is not empty (i.e., does not entirely consist of whitespace)

  • … does not entirely consist of a Python style comment (and is otherwise empty)

Example

Take as a test case the following content, and write it into a file distill-test.txt (or download it).

distill-test.txt

# whole-line comment
visible content     # though with a comment
		
the previous line contains two TAB characters
      starts at column >0, but is visible

the previousline is entirely empty

         # comment

Run your program distill.py on that file. The program’s output should look as follows.

$ python distill.py distill-test.txt
visible content     # though with a comment
the previous line contains two TAB characters
      starts at column >0, but is visible
the previousline is entirely empty