Re: Looking for Python programmers for testing.

["G. Milde" <g.milde@xxxxxx>]

On 12.09.06, G. Milde wrote:
> On 11.09.06, Jörg Sommer wrote:

Unfortunately, the patch doesnot solve the problem of mixed TAB and Space
use for indenting code lines.

Example

USE_TABS = 1; TAB = 8; Py_Indent_Level = 4;

After pressing TAB on every of the code lines below, the second is indented
with 4 spaces while the third is indented with one tab and the last with a
mix of tab and spaces in one line!

def unindent(self, indent=None): 
    if indent is None:
	if self.min_indent():
	    return

The problem is, that whitespace() will insert a mixture of tabs and
spaces as long as TAB != 0 and USE_TABS != 0. This might be solved by
using insert_spaces() instead of whitespace().


> > The old version sets TAB to zero if Py_Indent_Level != 8. 

I now see the idea behind this approach: the Python interpreter does an
'untab' with a tab value of 8:

   tabs are replaced (from left to right) by one to eight spaces such
   that the total number of characters up to and including the 
   replacement is a multiple of eight
   -- python2.4/html/ref/indentation.html

I.e. any other TAB setting will lead to immediate problems if tabs and
spaces are mixed in the script. Still ...

> I see two problems with this setting:
> 1. It would set TAB = 0 even if Tabs are used in the buffer
> 2. It uses the setting of Py_Indent_Level to determine if the user wants
>    tabs to indent python code.
     i.e. with the unpatched code, it is impossible to use "indent
     with 8 spaces".

My new proposal is 

  Py_Indent_Level
  
   USAGE
    variable Py_Indent_Level = 4
  
   DESCRIPTION
    `Py_Indent_Level' is the default, used for the buffer-local
    indent-level, for a buffer without indented code lines (e.g. a new one).
    
    The pre-set value of 4 spaces corresponds to the "Style Guide for Python
    Code" (http://www.python.org/dev/peps/pep-0008/)
    
    The special value 0 means use hard tabs ("\t") for indentation.

i.e. instead of

  * iferring the use of tabs from the relation of
    Py_Indent_Level and TAB
    
> > >> +   set_blocal_var(Py_Indent_Level == TAB, "py_use_tab");

    or

  * a second custom var for tab or spaces
  
> > > introducing a variable Py_Use_Tabs ...

tab use is mandated by Py_Indent_Level == 0. As no-one wants to
indent with 0 spaces, this will not limit the choice.

As a side effect: if the buffer local variable "py_use_tab" is replaced
by "py_indent_level" with a similar coding, auto-detection of indentation
can also determine and store the number of spaces used for one indent
level.


Two more problems with auto-detection in the dpatch:

  long literal strings with ''' ''' are not skipped
  continuation lines (other than """ """ strings) are not detected.

> > Inconsistent cases must be fixed by the user.

> Agreed. It would be nice if the auto-detection issued a warning in case
> of mixed tabs and spaces, though.

> Providing a function that replaces Tabs in indented code lines
> with Py_Indent_Level spaces might further facilitate this task.

The new version of pymode at jedmodes.sf.net/mode/pymode/ does
both. It comes with extensive documentation and a mode menu.

Günter

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