Re: Question on bounded / unbounded strings

[John Smith <yoursurrogategod@gmail.com>]

On Saturday, September 24, 2016 at 1:45:14 PM UTC-4, Dmitry A. Kazakov wrote:
> >>> If you need to separate a large string into a bunch smaller ones
> >>> that  do not have a pre-determined size, using a fixed string does not make
> >>> any sense.
> >>
> >> I *never* need that. It was discussed already.
> >
> > If a file is read in (the format is non-standard) and you now need
> > to  sift through the details of the file, you will need this.
> 
> Searching for a pattern / skipping irrelevant parts of the input do not 
> require that. No need to split anything.
> 

Then how would you accomplish this?

> >>> When you do need to build a string, it is far easier to have one
> >>> unbounded string that is added on to and then written out.
> >>
> >> No, it is easier with fixed strings.
> >
> > How?
> >
> > I've tried going to the example on your website, but it seems that that is down.
> 
> Hmm, it is not down:
> 
> http://www.dmitry-kazakov.de/ada/strings_edit.htm
> http://www.dmitry-kazakov.de/ada/components.htm#Parsers_etc
> 

I'll have a look when I get home.

> >>> Having a
> >>> fixed string means that I woul need something along the lines of a
> >>> recursive solution, since I can't extent the size of the string after
> >>> it's been instantiated.
> >>
> >> The output length for formatted output is always known. Normally the
> >> parts of a composite string are statically known, that precludes
> >> iteration or recursion. In other cases, like building a directory path
> >> from some structure, I first calculate the length and then declare the
> >> result string.
> >
> > No, it is almost always unknown in my experience :-). If I'm putting
> > together a report that needs to be e-mailed out, I have no idea how long
> > it will be. I would first need to do my thing, get the string returned
> > from it, append it to an accumulator string and after all of that was
> > done, I can now know its length.
> 
> But a mail body is not a string! If you send a MIME attachment the 
> natural way to do it is to use a stream as the source. String can be 
> used, but for short text mails only.
> 
> I believe AWS takes streams for attachment. My implementation of SMTP 
> certainly does:
> 
> http://www.dmitry-kazakov.de/ada/components.htm#GNAT.Sockets.SMTP.Client.Attach_Stream
> 

Sure it is.  This is especially true when it comes to sending out a string e-mail (and a bunch of HTML can be put on a single line.)  But the e-mail example is just one that I could think of on a dime.

I'll have a look at what you did when I get home.

> > If I were to first run my analysis, get the length of the string
> > (which is the result that will go out), then keep doing this until I'm
> > finished (at which point I will be able to figure out how big my
> > accumulator is supposed to be.) Now, I would have to re-run my analysis
> > again and then copy in the results into the my newly allocated
> > accumulator string. That would make for some needlessly complex logic in
> > my application (as opposed to just dump everything to an unbounded string.)
> 
> I would use a stream on top of a segmented buffer, e.g.
> 
> http://www.dmitry-kazakov.de/ada/components.htm#Storage_Streams
> 
> Or a FIFO if the producer of the content and the SMTP client are run by 
> different tasks.
> 
> You don't need to build all attachment in the memory in order to be able 
> to send it.
> 

I disagree.  If I write out the attachment to disk and then e-mail it, that's even more overhead.  Why do this?  Create a neat package in memory, e-mail it out and then forget about it.  Doing this operation in memory would be easier and faster.  And I don't have to worry about temporary files or any other files (as well as deleting the files, testing this additional logic, etc.)

> > However, if I ever need string functionality that I'm used to in
> > Python or C++, Unbounded strings are the only reasonable solution.
> 
> You used to use dynamic strings. But there is no evidence they really 
> simpler to use. In my code which varies from network protocols to 
> compiler developing tools and AI you will find almost no 
> Unbounded_Strings. Would it be simpler with Unbounded_Strings? I doubt it.
> 

When I get home, I'll have a look at what you've written.