On Sep 27, 2006, at 9:13 AM, Russell Campbell wrote:
To me, this was a poor design decision. I can't see NASA using
Python for
anything . . . "Well, the reason the first human mission to Mars
failed was
because someone accidentally deleted a Tab character, didn't notice
it, and
the landing program behaved differently than originally speced
out." Ok,
that's an extreme example, but the behavior of my programs matters
just as
much to my clients. At least with block delimiters like ENDIF, you
and the
program always know when a statement will execute even when someone
has
accidentally changed indentation. It's as bad a design flaw as
case-sensitivity.
It's as bad a design flaw as ENDIF is. Your example of a missing tab
would have the same result as a missing ENDIF - the code would not
compile when it was run. You'd get an error, and go back and fix it.
I know, because now that I code so much in Python, I routinely forget
to include ENDIFs, ENDFORs, etc. in my VFP code. They don't go by
unnoticed, though - the first time I run the code the compiler lets
me know in no uncertain terms!
Eric Raymond recounted his experience with his first coding in
Python (http://www.linuxjournal.com/article/3882). His initial
reaction was like yours:
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I immediately tripped over the first odd feature of Python that
everyone notices: the fact that whitespace (indentation) is actually
significant in the language syntax. The language has no analog of the
C and Perl brace syntax; instead, changes in indentation delimit
statement groups. And, like most hackers on first realizing this
fact, I recoiled in reflexive disgust.
I am just barely old enough to have programmed in batch FORTRAN for a
few months back in the 1970s. Most hackers aren't these days, but
somehow our culture seems to have retained a pretty accurate folk
memory of how nasty those old-style fixed-field languages were.
Indeed, the term ``free format'', used back then to describe the
newer style of token-oriented syntax in Pascal and C, has almost been
forgotten; all languages have been designed that way for decades now.
Or almost all, anyway. It's hard to blame anyone, on seeing this
Python feature, for initially reacting as though they had
unexpectedly stepped in a steaming pile of dinosaur dung.
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Then later, when he actually began using it, things changed:
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Of course, this brought me face to face once again with Python's pons
asinorum, the significance of whitespace. This time, however, I
charged ahead and roughed out some code for a handful of sample GUI
elements. Oddly enough, Python's use of whitespace stopped feeling
unnatural after about twenty minutes. I just indented code, pretty
much as I would have done in a C program anyway, and it worked.
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That's pretty much what happened with me. I thought it was wrong,
wrong, wrong, but did it because I had to. Once I started working
that way, it wasn't odd at all - after all, I am pretty religious
about indentation in my Fox code. After an hour or two it seemed
perfectly natural, and now having to write ENDIFs seems silly.
-- Ed Leafe
-- http://leafe.com
-- http://dabodev.com
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