Re: Ada standard and maximum line lengths

[Niklas Holsti <niklas.holsti@tidorum.invalid>]

On 13-01-31 11:10 , Stefan.Lucks@uni-weimar.de wrote:

> In any case, nobody should need line lengths of more than about 200
> characters. This is not a technological limit, this is related to human
> vision. The typical line length (about 80 characters) has been chosen to
> be well-readable by humans. (Actually, most people consider this a bit
> too large ... but let us stick with "about 80" for the sake of the
> argument.)

 [snip]

> The only reason to support longer lines would be to handle automatically
> generated code, that is *not* meant to be human-readable. In fact,
> writing tools to generate source code is (slightly) easier if one does
> not need to care about line ends at all, writing a source file into a
> single line ...

"Slightly" is right. It is very simple to make the source-code generator
insert newlines between lexical elements to keep lines from growing
unreasonably long.

In practice, when one is developing a program that generates source-code
(in Ada or other languages), it is often necessary to look at the output
to check that it is correct, or to understand why it is wrong, and this
is much easier if the output is not only broken into lines, but also
indented in the usual way.

A pretty-printer post-processor could be used to format single-long-line
output, but this raises the questions of how long input lines the
pretty-printer can handle, and whether it can handle syntactically or
lexically illegal or incomplete input. Also, if the source-code
generator itself does the indenting, incorrect indentation can be a good
clue for finding errors in the generator, in my experience.

So, developing a working automatic source-code generator is easier if
the generator produces code that is nicely broken into lines and nicely
indented. Generating a single long line is not the best way, unless the
output must be as short as possible (avoiding consecutive spaces or tabs
for indentation).

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
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