Goto (Posting On Python-List Prohibited)

[Peter J. Holzer]

On 2017-12-30 11:07:56 -0500, Dennis Lee Bieber wrote:
> On Sat, 30 Dec 2017 13:46:14 +0100, "Peter J. Holzer" <hjp-python at hjp.at>
> declaimed the following:
> 
> >I don't think this is correct. Structured programming is much older:
> >ALGOL 60 was already a block structured language and Dijkstra wrote
> >"goto considered harmful" in the late 1960s. Pascal appeared in 1970, C
> >in 1974. To me (who learned to program in BASIC on a CP/M machine), C
> >is very much a structured programming language. If structured
> >programming gained traction around 1980, it might even have been because
> >structured languages like C with good performance became widely
> >available.
> >
> 	There is a slight difference between just being block structured and
> full structured programming (at the time "one-entry/one-exit per
> construct".

I'd say there is a rather big difference: One is a programming paradigm,
the other a syntactic aid for the former. You can do structured
programming in assembler (I did in BASIC), but it is a lot easier and
natural in a block-structured language. I wasn't present when ALGOL was
invented (I wasn't even born then), but I am sure that the inventors
shared much of the mindset of "structured programming" (although the
name may not yet have been invented).

> Even Pascal still had a GOTO statement,

Yes. I don't know any language which enforces "pure" structured
programming. They all have some constructs (goto, break, return,
exceptions, ...) to leave a block early. I don't think that invalidates
my point that the concept of structured programming predates Pascal.

> and flow-charts were still part of documentation at school.

We learned about them in the 80's, too (along with Nassi-Shneiderman
diagrams). And in fact I still use them sometimes (although more
frequently to document processes for humans than for computers).
(I don't use NS diagrams at all anymore: They have no advantages over
pseudo code for me.)

> 	The /teaching/ of structured programming as a discipline didn't really
> show up until my final year in college (79-80) and the first few years at
> Lockheed

I can't comment on how wide-spread teaching of structured programming
was, since I am too young. But since Pascal was explicitely intended as
a teaching language for structured programming, there must have been at
least a few professors to teach it in the late 1960's.

> -- which was also a time period when such abominations as TEXTFOR,
> MORTRAN, and RATFOR were created to allow for doing structured programming
> in FORTRAN-IV

And regardless of the quality (or lack thereof) of these preprocessors
I'd argue that they were created (and used) because at the time many
programmers thought that structured programming was a good idea. 

Is there any mainstream (procedural) computer language invented after
1970 which doesn't try to encourage structured programming?

        hp

-- 
   _  | Peter J. Holzer    | we build much bigger, better disasters now
|_|_) |                    | because we have much more sophisticated
| |   | hjp at hjp.at         | management tools.
__/   | http://www.hjp.at/ | -- Ross Anderson <https://www.edge.org/>
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