Actually, spaces are better for indenting code.  The exact amount of
space taken up by one space character will always (or at least tend to
be) the same, while every combination of keyboard driver, operating
system, text editor, content/file format, and character encoding all
change precisely what the tab key does.

There's no use in typing "tab" for indentation when my text editor will
simply convert it to three spaces, or worse, autoindent and mix tabs
with spaces so that I have no idea how many actual whitespace characters
of what kinds are really taking up all that whitespace.  I admit it
doesn't usually matter, but then you go back to try and make your code
prettier and find yourself asking "WTF?"

Undoubtedly adding the second spark to the holy war,
Eli

I agree, use tabs.

Thanks Xah. I value your posts. Keep posting. And since your posts
usually cover broad areas of CS, keep crossposting. Don't go anywhere
Xah :-)

I wouldn't say that spaces are a hack, but tabs are superior.

Don't forget the laziness of programmers like me who don't put the
tabbing information in the source file. Vim deals with tabs well IMO,
but I almost never used to put the right auto-commands in the file to
get it set up right for other users.

Vim does this. We just have to use it.

Nope. Conversion is relatively easy. I've written programs to do this
myself, and everyone and his brother has also done this. Virtually every
programmer's editor that I've ever used can do this, and a great, great
many independent programs convert tabs to spaces. It's like saying,
"it's near impossible to write a calculator program." :-)

I bet that someone has a Perl one-liner to do it.

On any Debian system, try a "man expand" and see what you find. Also,
emacs and vim do it. Perl has a Text::Tabs module. TCL's

it. Oh wait, that's something else :-)

Nope again. It's easy, you just keep track of the virtual character
position as you decide whether to write a space or a tab. Computers do
the "counting" thing fairly well.

I've never thought of tabs-vs-spaces as a religious war. Anyway, the
authority of the programming environment will determine which one is
used. Have a good week Xah.

Oh God,  I agree with Xah Lee.  Someone take me out behind the chemical
sheds...

Iain

An old debate.  My $0.02 :

http://numeromancer.dyndns.org/~timothy/tab-width-independence/description.html

The idea can be extended to other programming languages.

TS

[...]

I fullheartedly disagree :)

So, no "essay" on this is necessary to read :->

Ciao,
   Oliver

The reality of programming practice trumps original intent of tab
characters.  The tab character and space character are pliable in that
if their use changes their semantics change.

If/when time comes where such info is embeded perhaps then tabs will be
OK.

---------------------------------------------------------------

I use spaces because of the many sources I've opened I have many times
sighed on opening tabed ones and never done so opening spaced ones.

I don't get mad, but sighing is a clear indicator  of negativity.
Anyway, the more code I write and read the less indentation matters to
me.  My brain can now parse akward source correctly far bettter than it
did a few years ago.

All the best,
Opalinski
opalpa@gmail.com
http://www.geocities.com/opalpaweb/

Bahaha, looks like someone hasn't thought things through very well.

Spaces, under a mono font, offer greater precision and expressivity in
achieving specific alignment. That expressivity cannot be captured by
tabs.

The difficulty in converting spaces to tabs rests not in any bridgeable
semantic gap, but in the lack of having any way whatsoever to express
using tabs what the spaces are expressing.

It's not /near/ impossible, it's /precisely/ impossible.

For instance, tabs cannot express these alignments:

 /*
  * C block
  * comment
  * in a common style.
  */

 (lisp
  (nested list
   with symbols
   and things))

 (call to a function
       with many parameters)
 ;; how do you align "to" and "with" using tabs?
 ;; only if "to" lands on a tab stop; but dependence on specific tab
stops
 ;; destroys the whole idea of tabs being parameters.

To do these alignments structurally, you need something more expressive
than spaces or tabs. But spaces do the job under a mono font, /and/
they do it in a completely unobtrusive way.

If you want to do nice typesetting of code, you have to add markup
which has to be stripped away if you actually want to run the code.

Spaces give you decent formatting without markup. Tabs do not. Tabs are
only suitable for aligning the first non-whitespace character of a line
to a stop. Only if that is the full extent of the formatting that you
need to express in your code can you acheive the ideal of being able to
change your tab parameter to change the indentation amount. If you need
to align characters which aren't the first non-whitespace in a line,
tabs are of no use whatsoever, and proportional fonts must be banished.

I was once a religous tabber until working on multiple source code sources,
now I am a religious spacer :)

My 2bits worth,

Aaron

<snip>

Yeah, that's really tough.  vi does just fine handling tabs.  vim does
an even better job, with mode-lines, = and :retab.

In my experience, the people who complain about the use
of tabs for indentation are the people who don't know
how to use their editor, and those people tend to use
emacs.

If I work on your project, I follow the coding and style standards you
specify.

Likewise if you  work on my project you follow the established
standards.

Fortunately for you, I am fairly liberal on such matters.

I like to see 4 spaces for indentation.  If you use tabs, that's what I

will see, and you're very likely to have your code reformatted by the
automated build process, when the standard copyright header is pasted
and missing javadoc tags are generated as warnings.

I like the open brace to start on the line of the control keyword.  I
can deal with the open brace being on the next line, at the same level
of indentation as the control keyword.  I don't quite understand the
motivation behind the GNU style, where the brace itself is treated as a

half-indent, but I can live with it on *your* project.

Any whitespace or other style that isn't happy to be reformatted
automatically is an error anyway.

I'd be very laissez-faire about it except for the fact that code
repositories are much easier to manage if everything is formatted
before
it goes in, or as a compromise, as a step at release tags.

Ashesh..

the following are 2 FAQ following this thread. Thanks.

Addendum: 2006-05-15

Q: What you mean by embeding tab position info into the source code?
How's that gonna be done?

A: Tech geekers may not realize, but such embedding of meta info do
exist in many technologies by various means because of a need. For
example, Mac OS Classic's resource fork and Mac OS X's bundling system,
unix shell script's shebang (#!), emacs and Python's encoding
declaration #-*- coding: utf-8 -*-, Unicode's BOM, CVS's
change-log insertion, Mathematica's source code system the Notebook,
Microsoft Word's transparent meta data, as well as HTML and XML's
various declarations embedded in the file. Some of these systems are
good designs and some are hacks.

Somehow tech geekers have the sense that source code must be a
plain text file containing nothing else but the programing code. This
may be a defendable position, but as we can see in the above examples,
this idea is primitive and does not address the various needs. If the
tech geekers have thought out about these issues, computing languages
and its source code may have developed into more powerful and flexible
integrated systems as the above standardized examples. For instance,
many commercial development systems actually already have such
meta-data embodied with the source code. (e.g. Borland Delphi,
Metrowerks's CodeWarrior, Microsoft Visual Studio, Wolfram Research's
Mathematica.) Some of which, not only embody development-related info
such as debug points or linking files, but also allow programers to
high-light code for visual purposes like a word processor, or even
display them visually as type-set mathematics.

Q: Converting spaces to tabs is actually easy. I don't see how spacess
lose info.

A: Here is a illustration on how it is not possible to convert spaces
to tabs. Suppose you are writing in a language where the indentation is
part of the semantics, not just for appearance. Now, suppose you have
these two lines:

1234567890
 A
   B

The first line has 2 space prefix and second line has 4 space prefix.
How, if you convert this to tabs, how do you know that's 1 and 2 tabs,
or 2 and 4 tabs? In essence, there is no way to tell how many tabs n
represents, where n is the smallest space prefix in the code, unless n
== 1.

The above demonstrates the information loss in using spaces for
indentation in a theoretical way. There are also practical problems. In
practice, many languages allow string literals like this myName="i love
you", and strings easily can have a run of spaces. One cannot simply
run a blind find-n-replace operation to replace all spaces to tabs. But
also, many unix languages contains a so-called construct of
heredoc as a mean to embed a literal block of text. For example,
here's a PHP construct of heredoc:

$novelText = <<<arbitraryCharsHereAsDelimiter
           (__)
           (oo)
    /-------\/
   / |     ||
  *  ||----||
     ~~    ~~
arbitraryCharsHereAsDelimiter;
}

Regardless of its design as a language construct, the purpose of
heredoc is that it allows programers to easily embed a text (a
large string), without worrying about the text containing sequence of
characters that may be meaningful to the language. If a language has
heredoc construct, then it is basically impossible to convert from
spaces to tabs, as that will botch literal string embedded in heredoc.
However, it is less of a problem to convert tabs to spaces, because the
frequency of spaces appearing in literal strings are far higher than
literal tabs.

Another practical issue is error recovery. Suppose, one uses 4 spaces
for a indentation. Now, it is not uncommon to see lines with odd number
of space prefixes such as 7 or 10 out of common sloppiness. Such error
would happen more often if spaces are used for indentation, and the
essence is that tabs enforce a semantic association and is impossible
to make a half-indentation.

Q: Well, i just like spaces because they are most compatible.

A: Sure, crass simplicity is always more compatible. Suppose a unixer
will say, he doesn't like HTML because it is fret with problems and
incompatibilities. He'd rather prefer plain text. And, indeed, a lot
unixers seriously think that.

---------------------------
PS in the answer to the first question, i gave the following examples
of IDE/Language that actually embed formatting info in the source code:
Borland Delphi, Metrowerks's CodeWarrior, Microsoft Visual Studio,
Wolfram Research's Mathematica

actually, i know Mathematica does, but i'm not quite sure about the
other examples. So, my question is, does any one knows a language or
IDE that actually allows the coder to manually highlight parts of the
code and this highlight stick with the file upon reopening, as if a
word processor?

  Xah
  xah@xahlee.org
 http://xahlee.org/