7.1 'Image for all types

It must be a shock to programmers coming from other languages, such as Python, that in Ada one couldn't directly output the value of a composite, but had to laboriously write one's own routine to do it field by field, then repeat if there was nesting of composites. Such a mechanistic process is more efficiently performed by a compiler than a programmer. And remember that, prior to Add Object'Image (AI12-0124), included in the Ada 2012 Technical Corrigendum, there was also the tedium of having to look up the subtype for an object and use My_Subtype'Image (My_Object) to obtain the image of an object.

'Image for all types (AI12-0020) adds the attribute 'Image for all types (see RM 4.10). It should be a boon for debugging.

Following on from this, Image attributes of language-defined types (AI12-0304) requires that 'Image works for the language defined container types. This uses the new [ ] array aggregate syntax from Container aggregates; generalized array aggregates (AI12-0212). For Maps it uses the form of a named array aggregate, e.g.:

for Trees the form is a positional array aggregate, e.g.:

for null containers the form is a null array aggregate, i.e.:

Put_Image should use a Text_Buffer (AI12-0340) adds package Ada.Strings.Text_Buffers (see RM A.4.12), to make it easier for users to redefine 'Image for their own purposes.

© 2021, 2022 Jeff Cousins