Re: ADA and return functions (Strings)

[sk <sknipe@ktc.com>]

Hi,

MDC :
> ... Integer'Spaceless_Image ...

I was thinking of for more complex types, 
timestamps for example. 

A "for Time'Image use My_Time_Image" might allow
for several possibilities :

1) I want date only.
2) I want time only
3) I want yyyy-mm-dd format
4) I want mm-dd-yyyy format
5) ... etc

Instead of asking the Ada language to standardize a
date/time image format which will not meet all needs, 
allow an 'Image substitution.

It could be tricky, but I think it might have less 
impact on the language than adding special attributes, 
such as "Spaceless_Image", to the predefined set of 
attributes.

In many ways, the 'Image and 'Value attributes have
parallels to the 'Read and 'Write attributes in terms 
of allowing the caller to define the presentation of
I/O data formats.

I realize of course, that nothing is really gained by 
'Image and 'Value substitution since they are directed
at the definite string type and 'Read and 'Write are 
directed at the abstract stream, but it could provide
a solution to the statement 

dewar@gnat.com (Robert Dewar) :
> ... But we are stuck now because people depend on 
> the existing annoying definition.

Let "people" depend upon their own definition, let the 
language worry about more critical things.

Another possible benefit is that one could define a 
simple "Hex_Image" function for example. One could 
then substitute with 

"for My_Integer_Type'Image use Hex_Image;" 

instead of having to instantiate an Ada.Text_Io.Integer_Io
and setting default base etc. and then use the string 
specific "Put" (which requires a constrained string, and
was a secondary point of another thread a week or two ago).

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