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Date: Mon, 20 Apr 2020 08:24:16 -0700 (PDT)
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Subject: Image attribute (yet again)
From: Stephen Davies <joviangm@gmail.com>
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Xref: reader01.eternal-september.org comp.lang.ada:58434
Date: 2020-04-20T08:24:16-07:00
List-Id: <comp.lang.ada>

Whilst looking at the new features for Ada 2020, I spotted:

 An implementation may transform the image generated by the default
 implementation of S'Put_Image for a composite subtype S in the
 following ways: 

 - If S is a composite subtype, the leading character of the image of
   a component value or index value is a space, and the immediately
   preceding character is an open parenthesis, then the space may be
   omitted. The same transformation is also permitted if the leading
   character of the component image is a space (in which case one of
   the two spaces may be omitted). [AARM note: This means that it is
   permitted to generate "(1 => 123, 2 => 456)" instead of
   "( 1 => 123, 2 => 456)".] 

Whilst it is nice that those in charge of the language are finally
acknowledging how annoying the leading space on numeric images is,
that just makes it more galling that they appear to still be doing
about it for scalar numeric types.

I understand that the default behaviour of "'Image" cannot possibly
be changed as it would cause massive incompatibility. But there are
other, simple solutions, e.g. new attribute, optional parameters, ...

One justification that might be given for doing nothing is that
"Trim(S'Image, Left)" can be used instead, but I disagree because:

- It requires adding with/use clauses for Ada.Strings and
  Ada.Strings.Fixed.

- "S'Trim_Image" would still be nicer (just as "First_Element(C)"
  can be used instead of "Element(First(C))".