Tab Wars

EPISODE II
It is a period of civil unrest in programming circles as the interesting and highly irrelevant conflict over programming style rages on. While all citizens agree on the importance of indentation, turmoil has arisen with the emergence of the TAB CHARACTER.

Striking from a secret base on ASCII 9, the Tab stealthily convinces amateur and professional programmers alike to use its alluring single-character-indent to create indented code, yet its highly display-dependent behaviour could spell certain doom for GOOD PROGRAMMING PRACTISES.

It is now up to a small band of intrepid programmers to rebel against the Tab to restore order to the University...

Hehehe... OK its time to go public on this! (You're real crayzeh Matt!)

Obviously the debate is not new. Wikipedia even makes reference to it in the Tab article:

In computer programming, the use of tabs for code formatting and indentation is an ongoing debate. Programmers are generally divided into two camps - those who use hard tabs in their code, and those who configure their editors to insert actual space characters when they press the tab key. When tabs are replaced to spaces in this way they are referred to as soft tabs.

The reason I am currently in a ranting mood is that I have just gotten my verification on my programming project back and failed every test because my output did not match the expected. Even after I spent an hour and a half in the lab trying to get my output to match, I could not. Finally, it turned out the "expected" output was using hard tabs (ASC-9) while my program was using soft tabs (a set of SPACEs, ASC-32). What made it altogether confusing was that some of the tabs looked like spaces, some of them looked like tabs (only when selected) and in general the output, being displayed in three different environments looked completely different.

Rant over, now time for the arguments. This is a long-running debate I've been having with Tim - so feel free to comment any arguments you may have (I won't post your emails without permission).
I simply find so-called "hard tabs" to be very annoying (and feel I have a right to complain since I've been editing an awful lot of other people's hard-tabbed code as of late). Essentially, one will notice that every OS and in fact every program can choose to display tabs differently. Some display them as four spaces, some display as eight. Even more annoying is when they simply choose a number of pixels, and it doesn't line up with any text columns at all.

ASCII 9 is the only displayable ASCII character (besides line-break) which does not take up exactly one char-width in a monospaced font. Therefore it ruins the column spacing (ie. programs you wish to keep within 80 columns will be difficult to count) - furthermore this makes it impossible to get lines with different numbers of tabs to line up. The bottom line is: hard-tabs give programmers no control over how their code appears.

With soft-tabs (ie. spaces) it is possible to have complete control over appearance. All characters are the same width and display is identical on all monotype displays. Surely any style-control freak wants this advantage.

There seem to be only two advantages of hard-tabs - smaller file size, and ease of typing. Smaller source code files are hardly relevant today. And most modern editors will (or should) automatically type a predetermined number of spaces when the Tab key is hit. Personally, when working with tab characters, I find it disturbing when the tabs at the end of a line (eg. between code and comment) move around as I'm typing.

The only argument I find remotely valid is the one that tabs make code more "dynamic" ie. the indent length is not fixed after code has been typed - the user can alter the display dynamically. The simple response to this is - I have never seen a program which allows you to choose the internal representation of tab size. Therefore it is not up to the user, but the user's program, as to how tabs are represented. Don't like.

And finally, lets see what Wiki has to say on the Indent style page:

Many early programs used tab characters for indentation, for simplicity and to save on source file size. Unix peripherals would generally have tabs equivalent to eight characters, while Macintosh environments would set them to four, creating confusion when code was transferred back and forth. Modern programming editors are now often able to set arbitrary indentation sizes, and will insert the appropriate combination of spaces and tabs. They can also help with the cross-platform tab confusion by being configured to insert only spaces.

Tab:

There are many arguments for and against using hard tabs in code. What can be said without doubt is that one early benefit of tabs, i.e. compression (see above), is now less relevant as storage is so cheap, and sophisticated compression algorithms can provide much greater benefits.

Tabs versus Spaces: An Eternal Holy War

So go ahead, rant your brains out, refute, agree... it will be interesting to see if you join the rebellion or empire.

"The section now illuminated is the Floating Point Unit, one of my personal favorite units."
- Professor Frink