[Python-Dev] Indentation oddness...

[Robert Kern]

On 2009-05-29 19:08, Dino Viehland wrote:
> Consider the code:
>
> code = "def  Foo():\n\n    pass\n\n  "
>
> This code is malformed in that the final indentation (2 spaces) does not agree with the previous indentation of the pass statement (4 spaces).  Or maybe it's just fine if you take the blank lines should be ignored statement from the docs to be true.  So let's look at different ways I can consume this code.
>
> If I use compile to compile this:
>
> compile(code, 'foo', 'single')
>
> I get an IndentationError: unindent does not match any outer indentation level
>
> But if I put this in a file:
>
> f= file('indenttest.py', 'w')
> f.write(code)
> f.close()
> import indenttest
>
> It imports just fine.

The 'single' mode, which is used for the REPL, is a bit different than 'exec', 
which is used for modules. This difference lets you insert "blank" lines of 
whitespace into a function definition without exiting the definition. Ending 
with a truly empty line does not cause the IndentationError, so the REPL can 
successfully compile the code, signaling that the user has finished typing the 
function.

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco