Prothon Prototypes vs Python Classes

John Roth newsgroups at
Mon Mar 29 23:04:06 CEST 2004

"Terry Reedy" <tjreedy at> wrote in message
news:mailman.73.1080588424.20120.python-list at
> "John Roth" <newsgroups at> wrote in message
> news:106gg1jifa2n9c2 at
> > I think you misunderstood. There is no "standard" length of
> > a tab. A tab is supposed to insert (or otherwise render the
> > equivalent of inserting) enough spaces to go to the next "tab stop",
> > which by convention is a multiple of 8 columns on a fixed
> > width mechanical typewriter. This is where tabs originated.
> Actually, the mechanical typewrite standard (in US, 1960s) was every 5
> spaces == 1/2 inch (10 chars per inch, fixed).  That was also the standard
> paragraph indent.  WordPerferct, for one program, stuck with 1/2 inch even
> as it accommodated different fixed and variable pitched fonts.  I remember
> thinking 8 spaces a bit weird when I first used Unix (early 80s).

You're right about that, although that was only for the 1st tab. After
that, it was whereever you needed them for columns.

> Power-of-2 4 and 8 are computerisms.  Don't remember about Teletypes, nor
> about typewriters in non-inch countries.

I don't think it was a power of two thing. I very vaguely remember
some papers on the "ideal" tab spacing for inserting tabs in TTY
data streams. They were there to shrink runs of spaces to
something the mechanical teletypes could move over faster.
Some of the computations to insert a tab and then a specific
number of nulls to compensate for the exact mechanics at the
other end got quite intricate.

John Roth
> Terry J. Reedy

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