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From: Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP>
Newsgroups: comp.lang.ada
Subject: Re: Your wish list for Ada 202X
Date: Sun, 30 Mar 2014 13:46:41 +0000 (UTC)
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Date: 2014-03-30T13:46:41+00:00
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On 2014-03-30, francois_fabien@hotmail.com <francois_fabien@hotmail.com> wrote:
>
> One wish to ease Input/output :
> To have some equivalent of C primitive : printf("%c %c %c %c %c \n %c %c %c %c %c \n",
>

We have just had that discussion a couple of weeks or so ago. :-)

I also would like to see something like that in Ada, but I believe the
actual formatting is a attribute of the data type and is not something
which should be implemented within a I/O package as such.

My general idea is that when you define a data type, you also add support
for External_To_Internal and Internal_To_External conversions to the
data type.

At runtime, the Ada version of printf would call the Internal_To_External
support code within the data type along with the fragment of the format
for the entity in question (and which could include a optional display
length and precision).

Either a exception would be raised (if the requested conversion was
invalid) or the formatted output would be returned to the Ada version
of printf ready for direct inclusion in the output buffer.

As was pointed out the last time I suggested this, if the format string
was a literal, you could even check this at compile time, just as gcc
does for a C program.

Simon.

-- 
Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP
Microsoft: Bringing you 1980s technology to a 21st century world