Re: conversion

[aek@vib.usr.pu.ru (Alexander Kopilovitch)]

>The catch is that unbounded_string can not be used in context of string.
>This posses some design inconveniences and requires converting back and forth
>from string to unbounded_string multiple times.

Exactly. This is very inconvenient (perhaps, most inconvenient) feature of
Ada language.

Certainly, a chorus tells you that Ada is not C, but what about Pascal, which
has much more resemblance with Ada? Pascal isn't C, it does not rely heavily
upon pointers, but at the same time it has quite good and usable strings.

The chorus also tells you that in Ada you should not need those conversion
too often. Well, they are honest enough, they simply do not use Ada for
a job and in an environment where you must mix varying strings and constant
strings here and there, and at the same time you can't afford several weeks
for design for every change in specifications.

Ada simply understimates need of strings in non-numerical world (almost like
Fortran IV, that is, before Fortran 77). I'm sure that Ada people would cry
very loudly if there were similar situation with Integer type: imagine that
there is unconstrained (for value, not for storage size) type Integer, which
objects must be constrained (by value). Then, there are types Bounded_Integer
and Unbounded_Integer. Unbounded_Integer is good for general use, except that
you always have to write explicit conversion when you assign a literal (say,
1 or 0) to an object of Unbounded_Integer type (currently Ada Integer is like
a Pascal string in this respect).



Alexander Kopilovitch                      aek@vib.usr.pu.ru
Saint-Petersburg
Russia