[Geany] Problem: about tabs and indentation.

[Joerg Desch]

On Fri, 11 Jul 2008 15:00:38 +0100
Nick Treleaven <nick.treleaven at btinternet.com> wrote:

> > Not only this, IMO it is necessary to distinguish between tab width
> > and indentation width. Does Scintilla support this differentiation?
> 
> There's SCI_SETINDENT vs. SCI_SETTABWIDTH, but I haven't tried it:
> http://scintilla.sourceforge.net/ScintillaDoc.html#SCI_SETINDENT

Thanks for the link.


> > Is the support for "tab width" and "indentation width" a different
> > Scintilla configuration? Or is it necessary to add this to the Geany
> > core?
> 
> What should the difference be?

As I could read in the Scintilla docs (your link), Scintilla supports
both, real tab-width and indentation-with.

The difference is (or should be), that tabs are some kind of
"compression". Tabs are normally used without a special file type in mind.

Indentation is a more logical thing. The indentation depends on the file
type and the logical content (surrounding the cursor). So indentation
uses whitespaces (and so tabs) to indent the line to this logical
position.

For example: Writing a simple C-function, the indentation is a multiple
of 4.

void foo ( int i )
{
    if ( i>0 )
        ....


Another example is Emacs. It uses indentation for "hanging arguments" too.

void foo ( int i )
{
    if ( i>0 )
        some_function_call(long_parameter_name_as_example,
                           second_long_parameter);


Pressing "indent" in Emacs at "second_long_parameter" indents the line
according to the first parameter. This is not a multiple of 4. Thats what
I mean with "logical thing".

When tabs are enabled, most editors I know uses tabs within whitespaces
to realise the indentation. In the above example, the indentation would
be done with three tabs and three spaces.


> > To obtain tabs (if enabled) it would be good if 8 (or x) spaces are
> > replaced with a tab right after the indentation (Ctrl-I). What is the
> > right way to do this? Can you point me to an file/function which
> > should be patched?
> 
> I don't know what you mean, I'm not sure why we need to replace
> spaces/tabs.

It's just for consistency reasons. If tabs are enabled, they should be used.


To resume this thread:

Geany currently configures tabs with SCI_SETTABWIDTH. To separate tabs
and indentation, the configuration dialog should ask for the indentation
width and set SCI_SETINDENT with this value. There must be a hook to
change SCI_SETINDENT for each filetype. Futhernore, it would be nice, if
the configuration dialog would support SCI_SETTABINDENTS(bool) too.

Thanks for your answers. I think I'll have a look at this as soon as I
have some spare time.

-- 
Email: Joerg Desch <jd DOT vvd AT web DOT de>