Re: Ada standard and maximum line lengths

[Maciej Sobczak <see.my.homepage@gmail.com>]

W dniu poniedziałek, 28 stycznia 2013 09:18:43 UTC+1 użytkownik Dmitry A. Kazakov napisał:

> > I was reading the Ada 2012 standard and found this, I was just wondering
> > why there is a maximum line length, it's not like we parse the language a
> > line at a time.
> 
> It is. I always accumulate a whole line before parsing it.

But it is an implementation detail of your particular parser. There is nothing in the concept of parsing itself that would require it.

> > Why not just accept it as a stream of tokens and if there
> > are line breaks, ignore?
> 
> For multiple reasons. Specifically regarding Ada, the language has syntax
> elements bound by the line end, e.g. comments etc.

There is no problem reading the stream until some token (newline) is found. Especially if the whole purpose of reading is to ignore the input, as is the case with comments.

I do not see anything that would prevent the implementation that accepts potentially indefinite line lengths, while still putting arbitrary limits on identifiers. The implementation details of some existing parser (like yours) is not a satisfactory explanation.

I would not be surprised if the permission to limit is a leftover from the ice age of line printers, without any real association with today's systems.

-- 
Maciej Sobczak * http://www.msobczak.com * http://www.inspirel.com