Re: Question on bounded / unbounded strings

[John Smith <yoursurrogategod@gmail.com>]

On Thursday, September 22, 2016 at 3:25:18 AM UTC-4, Dmitry A. Kazakov wrote:
> On 22/09/2016 04:10, John Smith wrote:
> 
> > I've found the ease with which you can append or manipulate unbounded
> > strings to be very convenient.
> 
> 1. There is no need to append to a string in no less than 90% of cases.

The percentage in this case depends on what application you are developing.  Sometimes you will need to do this more often, sometimes less often.

> 
> 2. Unbounded_String manipulations are *very* inconvenient. Largely 
> because of their design flaw in Ada (no array interface), but nonetheless.

Yes, there is that.  However, that's not a very real inconvenience.  I can easily get the length of the string, get a sub-string, find a sub-string in the main string, etc.

If anything, a fixed string is less convenient since you need to walk on eggshells and cannot simply assign a new value to the existing string.

> 
> > Furthermore, I don't need to worry about
> > computing the bound of my string.
> 
> Neither do I, I never ever used bounded strings. They are totally 
> useless, IMO.
> 

When I said bound, I meant the length ;-)

> > But I genuinely am curious about your view on this and why.
> 
> As I said in 90% cases the string is given, it is an input. All strings 
> derived from the input strings are substrings (or their derivatives).
> 

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.

> The use cases like tokenizing are virtually non-existent, they are just 
> bad programming practices coming from scripting languages which have no 
> decent support of string characters iteration and from languages 
> incapable to return strings as a result of function call.
> 

Could you please give an example.  I'm used to Python and it's trivial to have a function return a string.

> As for 10% when strings are output, e.g. string formatting, unbounded 
> strings are no more usable. The output length is usually fixed 
> consisting out of fields. The substrings are aligned in the fields. It 
> is far easier with plain strings and substrings.
> 

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.  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 idea of using Unbounded_String as an accumulator, e.g. for some 
> messages log, is just awful. It won't work and at the end you will need 
> to have a special data structure (text buffer) for this (with plain 
> strings as building blocks).
> 

Why won't it work?  I've built HTML files and small reports using an unbouded string and it worked fine.

I don't agree with you on this topic.