Please review and comment

Please review and comment

[James Rogers]

A recent posting in comp.lang.ada from a newbie requested a document
listing common Ada programming idioms. This request seemed quite 
reasonable to me. As a result I have started to create such a 
document. Currently I have only a short introduction and a table of
contents. I would like comments on the current table of contents.
Please suggest additional subject matter, as well as possible 
reorganizations.

Thank you

Jim Rogers
Colorado Springs, Colorado USA

Ada Idioms and Source Code Examples

                                          James Rogers

                                         Last Updated July 31, 2001



This document presents several of the most common Ada coding idioms
including simple source code examples. This
document is not intended to be a full tutorial on the Ada language.
Instead, it is intended to be a tool for rapid reference to
common Ada coding idioms. 

When learning any new language it is important to learn how to design
your code to most fully cooperate with the features of the
language. It is common for a person to try to design code for a new
language using patterns and idioms from the person's most
familiar language. One old quote is "A good programmer can write Fortran
in any language". The sad truth is that you will not get
the greatest benefit from a language if you do not learn to "think" in
terms of that language. 


                                       Table of Contents

   1.Defining Data Types 
        1.Defining Integer Types 
        2.Defining Modular Types 
        3.Defining Enumeration Types 
        4.Defining Floating Point Types 
        5.Defining Fixed Point Types 
        6.Defining Array Types 
        7.Defining Record Types 
        8.Defining Discriminant Records 
        9.Defining Record Layouts 
       10.Defining Tagged Types 
   2.Looping 
        1.Simple Loop 
        2.While Loop 
        3.For Loop 
   3.Branching 
        1.if then else 
        2.case statement 
   4.I/O 
        1.Text IO 
        2.Sequential IO 
        3.Direct IO 
        4.Stream IO 
   5.Exceptions 
        1.Defining Exceptions 
        2.Handling Exceptions 
        3.Using the package Ada.Exceptions 
   6.Packages 
        1.Package Specification 
        2.Package Body 
        3.Separates 
        4.Hierarchical Packages 
   7.Subprograms 
        1.Functions 
        2.Procedures 
   8.Concurrent Programming 
        1.Tasks 
             1.Task Definitions 
             2.Task Bodies 
             3.Task Rendezvous 
             4.The Accept Statement 
             5.Selective Accepts 
        2.Protected Objects 
             1.Protected Object Specifications 
             2.Protected Bodies 
             3.Protected Functions 
             4.Protected Procedures 
             5.Protected Entries 
             6.Requeuing 
        3.Pragma Atomic 
        4.Pragma Volatile 
   9.Generics 
        1.Generic Formal Parameters 
        2.Instantiation of Generic Units 
  10.Memory Management 
        1.Dynamic Memory Allocation 
        2.Dynamic Memory Deallocation 
        3.Storage Pools 
  11.Abstract Types 
        1.Defining Abstract Types 
        2.Using Abstract Types 
        3.Ada.Controlled 
        4.Ada.Limited_Controlled

Re: Please review and comment

[tmoran]

Could you give an example of what you have in mind?
One topic I don't see is "is limited".  As I recall, it took me the
longest time to figure out "why would anyone make something 'limited'?"
Now I think of using a limited type for a 'handle' as an idiom.
Or a local declaration to get a string of unknown length.
Are those the sorts of things you have in mind?

Re: Please review and comment

[James Rogers]

Yes, these are the sort of things I have in mind.

When the document is complete I plan to submit it to Adapower.com.

Jim Rogers
Colorado Springs, Colorado USA

tmoran@acm.org wrote:
> 
> Could you give an example of what you have in mind?
> One topic I don't see is "is limited".  As I recall, it took me the
> longest time to figure out "why would anyone make something 'limited'?"
> Now I think of using a limited type for a 'handle' as an idiom.
> Or a local declaration to get a string of unknown length.
> Are those the sorts of things you have in mind?

Re: Please review and comment

[Ted Dennison]

In article <3B67526E.D7E19382@worldnet.att.net>, James Rogers says...
>
>listing common Ada programming idioms. This request seemed quite 
.
>contents. I would like comments on the current table of contents.

As a general comment, the organization seems a little backwards. The
organization you showed looks a lot like the organization of the LRM, which is
not exactly a beginner-friendly document. :-) It looks like you are planning on
presenting each feature of Ada, and then discuss what can be done with it. A
newbie is probably going to want to know the opposite: how one does X in Ada. 

The rest of my comments pretty much flow from the first one.

I don't see anything in there explicitly about strings. That seems to be the
newbie's biggest mental stumbling block with Ada, and I'm sure they'd go looking
for it in your document. There is a section on arrays, which presumbably would
include this information. But for a newbie, I'd suspect it would be more useful
to introduce the material as "how to do strings", then later point out that many
of the same techniques (excepting of course, the ones relying on Ada.Strings.*)
work for *any* array.

Also, there should probably be something in there on bit-accessable data
structures, like packed boolean arrays, rep-ed clause boolean-only records, and
modular types, and when each is appropriate.

I'd be sure to put in something basic on passing parameters. Newbies often have
the mis-impression that the data for all parameters is always copied, and thus
pointers should be used for efficiency.

---
T.E.D.    homepage   - http://www.telepath.com/dennison/Ted/TED.html
          home email - mailto:dennison@telepath.com

Re: Please review and comment

[Ted Dennison]

In article <3B677A4F.FB58838C@worldnet.att.net>, James Rogers says...
>When the document is complete I plan to submit it to Adapower.com.

If you actually make it as complete as you say you are going to, I'd suggest
using the GNU Free Documentation License (http://www.gnu.org/licenses/fdl.html .
If it ends up as complete as you appear to plan, and has a royalty-free license,
an actual print publisher might conceivably be convinced to make a print run of
it. It'd be cool to have an "Ada for newbies (dummies use C)" book available in
bookstores. :-)

---
T.E.D.    homepage   - http://www.telepath.com/dennison/Ted/TED.html
          home email - mailto:dennison@telepath.com

Re: Please review and comment

[Preben Randhol]

On Wed, 01 Aug 2001 15:01:40 GMT, Ted Dennison wrote:
> In article <3B677A4F.FB58838C@worldnet.att.net>, James Rogers says...
>>When the document is complete I plan to submit it to Adapower.com.
> 

> If you actually make it as complete as you say you are going to, I'd suggest
> using the GNU Free Documentation License (http://www.gnu.org/licenses/fdl.html .
> If it ends up as complete as you appear to plan, and has a royalty-free license,
> an actual print publisher might conceivably be convinced to make a print run of
> it. It'd be cool to have an "Ada for newbies (dummies use C)" book available in
> bookstores. :-)

New Riders <http://www.newriders.com/> have publish several books that
also are freely available for download. 

http://www.newriders.com/books/title.cfm?isbn=0735700788
http://www.newriders.com/books/title.cfm?isbn=1578701902
http://www.newriders.com/books/title.cfm?isbn=0735709246
etc...

so perhaps they are interested.

Preben
-- 
�Don't use C;  In my opinion,  C is a library programming language
 not an app programming language.�  - Owen Taylor (GTK+ developer)

Use Ada 95, a free language. More info at http://www.adapower.com/

Re: Please review and comment

[Marin David Condic]

Consider also looking at any FAQs that are out there. One thing that comes
up frequently is Text_IO and how to output integers, floast, etc.

MDC
--
Marin David Condic
Senior Software Engineer
Pace Micro Technology Americas    www.pacemicro.com
Enabling the digital revolution
e-Mail:    marin.condic@pacemicro.com
Web:      http://www.mcondic.com/


"Ted Dennison" <dennison@telepath.com> wrote in message
news:dEU97.13861$ar1.44074@www.newsranger.com...
> In article <3B67526E.D7E19382@worldnet.att.net>, James Rogers says...
> >
> >listing common Ada programming idioms. This request seemed quite
> .
> >contents. I would like comments on the current table of contents.
>
> As a general comment, the organization seems a little backwards. The
> organization you showed looks a lot like the organization of the LRM,
which is
> not exactly a beginner-friendly document. :-) It looks like you are
planning on
> presenting each feature of Ada, and then discuss what can be done with it.
A
> newbie is probably going to want to know the opposite: how one does X in
Ada.
>
> The rest of my comments pretty much flow from the first one.
>
> I don't see anything in there explicitly about strings. That seems to be
the
> newbie's biggest mental stumbling block with Ada, and I'm sure they'd go
looking
> for it in your document. There is a section on arrays, which presumbably
would
> include this information. But for a newbie, I'd suspect it would be more
useful
> to introduce the material as "how to do strings", then later point out
that many
> of the same techniques (excepting of course, the ones relying on
Ada.Strings.*)
> work for *any* array.
>
> Also, there should probably be something in there on bit-accessable data
> structures, like packed boolean arrays, rep-ed clause boolean-only
records, and
> modular types, and when each is appropriate.
>
> I'd be sure to put in something basic on passing parameters. Newbies often
have
> the mis-impression that the data for all parameters is always copied, and
thus
> pointers should be used for efficiency.
>
> ---
> T.E.D.    homepage   - http://www.telepath.com/dennison/Ted/TED.html
>           home email - mailto:dennison@telepath.com

Re: Please review and comment

[Ehud Lamm]

You can find a list of Ada idioms I started creating at
http://www.free-conversant.com/ehudlamm/ada/idioms.html . It is far from
being complete, but I never found the time to update the page, when new
ideas came (now, of course, I don't remember what I wanted to add..

Anyway, that's closer to what I'd consider idiom - concise and specific.

Ehud

Re: Please review and comment

[Ehud Lamm]

Ted Dennison <dennison@telepath.com> wrote in message
news:dEU97.13861$ar1.44074@www.newsranger.com...
>
> I don't see anything in there explicitly about strings. That seems to be
the
> newbie's biggest mental stumbling block with Ada, and I'm sure they'd go
looking
> for it in your document. There is a section on arrays, which presumbably
would
> include this information. But for a newbie, I'd suspect it would be more
useful
> to introduce the material as "how to do strings", then later point out
that many
> of the same techniques (excepting of course, the ones relying on
Ada.Strings.*)
> work for *any* array.


In fact the major problem is understanding how to (efficiently) use
unconstrained array types. Strings are but an important specail case.
But this issue is more in line for the FAQ than from an idiom list, which I
think of as more advanced. In my idiom list what  I say about strings is
"use Ada.Strings.*" I alos have a docuement called "intro to Ada strings"
(this was online on my previous site, I am going to put it up again
sometime. Meanwhile, I can mail it if anyone wants. It is for complete
beginners).


Ehud

Re: Please review and comment

[Ted Dennison]

In article <9k9a46$8f1$1@news.huji.ac.il>, Ehud Lamm says...
>
>think of as more advanced. In my idiom list what  I say about strings is
>"use Ada.Strings.*" I alos have a docuement called "intro to Ada strings"
>(this was online on my previous site, I am going to put it up again
>sometime. Meanwhile, I can mail it if anyone wants. It is for complete
>beginners).

I suspect I've seen it before (it sounds familiar). But you can send it along if
you like.

I would actually tell beginners to use perfectly-sized strings, and only resort
to Ada.Strings.* when the above can't be easily done. Newbies can indeed be
pointed at the spec for Ada.Strings.Unbounded without much other explanatory
text. Its the techniques for creating and dealing with perfectly-sized strings
in Ada that really need to be shown.

Its true that Strings are, in a way, just a special case of dealing with
unbounded arrays. However, they are also the case that a newbie is most likely
to stumble across first. Get them comfortable with strings, then show them that
*any* array can be used this way, and watch the mental lightbulb go on. Its
kinda fun whenever I do it.

---
T.E.D.    homepage   - http://www.telepath.com/dennison/Ted/TED.html
          home email - mailto:dennison@telepath.com

Re: Please review and comment

[Ehud Lamm]

Ted Dennison <dennison@telepath.com> wrote in message
news:VlX97.14112$ar1.47292@www.newsranger.com...
> In article <9k9a46$8f1$1@news.huji.ac.il>, Ehud Lamm says...

> I would actually tell beginners to use perfectly-sized strings, and only
resort
> to Ada.Strings.* when the above can't be easily done. Newbies can indeed
be
> pointed at the spec for Ada.Strings.Unbounded without much other
explanatory
> text. Its the techniques for creating and dealing with perfectly-sized
strings
> in Ada that really need to be shown.
>
>

> Its true that Strings are, in a way, just a special case of dealing with
> unbounded arrays. However, they are also the case that a newbie is most
likely
> to stumble across first. Get them comfortable with strings, then show them
that
> *any* array can be used this way, and watch the mental lightbulb go on.
Its
> kinda fun whenever I do it.
>

Amen to that. You just rephrased what I thought I said...

(In fact I recall submitting some FAQ entries on working with fixed sized
strings - of type String - maybe they are on AdaPower somewhere).

Ehud

Re: Please review and comment

[Ehud Lamm]

Ted Dennison <dennison@telepath.com> wrote in message
news:VlX97.14112$ar1.47292@www.newsranger.com...
> In article <9k9a46$8f1$1@news.huji.ac.il>, Ehud Lamm says...
> >
> >think of as more advanced. In my idiom list what  I say about strings is
> >"use Ada.Strings.*" I alos have a docuement called "intro to Ada strings"
> >(this was online on my previous site, I am going to put it up again
> >sometime. Meanwhile, I can mail it if anyone wants. It is for complete
> >beginners).
>
> I suspect I've seen it before (it sounds familiar). But you can send it
along if
> you like.
>

I am pretty sure most c.l.a readers so me mention it a couple of times.
Anyway, I uploaded it to my experimental site at
http://www.free-conversant.com/ehudlamm/ada/strings.html in the hope that
it will help someone.

Ehud

Re: Please review and comment

[Navid Azimi]

What about putting links or information about how to -start- programming in
Ada? I'm more confused on how to get it, say a simple hello world, running
as opposed to problems with strings and arrays. I dont know which
program/compiler to download, or what extension I need on my file, or
anything simple of that sorts.

All these different names about Gtk+, AdaGtk, etc, etc.. are very confusing
for a newbie to Ada like me.

- K

PS. I'm on Win 98 SE

"Afterall its people likeme you are trying to help =)"


"Ehud Lamm" <mslamm@mscc.huji.ac.il> wrote in message
news:9k991i$7o4$1@news.huji.ac.il...
> You can find a list of Ada idioms I started creating at
> http://www.free-conversant.com/ehudlamm/ada/idioms.html . It is far from
> being complete, but I never found the time to update the page, when new
> ideas came (now, of course, I don't remember what I wanted to add..
>
> Anyway, that's closer to what I'd consider idiom - concise and specific.
>
> Ehud
>
>

Re: Please review and comment

[tmoran]

>What about putting links or information about how to -start- programming in
>Ada? I'm more confused on how to get it, say a simple hello world, running
>as opposed to problems with strings and arrays. I dont know which
>program/compiler to download, or what extension I need on my file, or
>anything simple of that sorts.
  Aonix (look at www.aonix.com) makes available a $0 downloadable version.
I believe it's IDE is like that of Visual C++ .
  You can get the public version of Gnat (3.13p for Windows, IIRC).  Look
at www.adapower.com  For simple command line use, create a program in
a text file of arbitrary name and the gnatchop program.  That will
chop a file in separate pieces, creating abc.ads for "package abc" and
abc.adb for "package body abc" or "procedure abc".  Then, if "procedure hi"
is your "main", "gnatmake hi" will compile hi.adb and anything it needs.
Look in www.adapower.com for non-command line IDEs for Gnat, if you like.

>All these different names about Gtk+, AdaGtk, etc, etc.. are very confusing
>for a newbie to Ada like me.
  For Hello World you don't need any of those - ignore them for now.
They are there to simplify life for complex "WIMP" programming.

Re: Please review and comment

[Martin Dowie]

Ehud,

I'm intrigued by the last sentence 'For more ideas, and to learn
what NOT to do, see also "Ada 95 Quality and Style Guide:
Guidelines for Professional Programmers."'

Are you saying this guide is pants? :-)

Martin


Ehud Lamm <mslamm@mscc.huji.ac.il> wrote in message
news:9k991i$7o4$1@news.huji.ac.il...
> You can find a list of Ada idioms I started creating at
> http://www.free-conversant.com/ehudlamm/ada/idioms.html . It is far from
> being complete, but I never found the time to update the page, when new
> ideas came (now, of course, I don't remember what I wanted to add..
>
> Anyway, that's closer to what I'd consider idiom - concise and specific.
>
> Ehud
>
>

Re: Please review and comment

[Ehud Lamm]

Martin Dowie <martin.dowie@nospam.baesystems.com> wrote in message
news:3b68fb88$1@pull.gecm.com...
> Ehud,
>
> I'm intrigued by the last sentence 'For more ideas, and to learn
> what NOT to do, see also "Ada 95 Quality and Style Guide:
> Guidelines for Professional Programmers."'
>
> Are you saying this guide is pants? :-)
>


Heavens no!

It is just that idioms in general tell you how things can be done, but don't
tell you things to avoid: that's where a style guide can be handy.

Ehud

Re: Please review and comment

[Martin Dowie]

Ehud Lamm <mslamm@mscc.huji.ac.il> wrote in message
news:9kb9ba$eaa$1@news.huji.ac.il...
> > I'm intrigued by the last sentence 'For more ideas, and to learn
> > what NOT to do, see also "Ada 95 Quality and Style Guide:
> > Guidelines for Professional Programmers."'
> >
> > Are you saying this guide is pants? :-)
> >
>
>
> Heavens no!
>
> It is just that idioms in general tell you how things can be done, but
don't
> tell you things to avoid: that's where a style guide can be handy.

:-))

Re: Please review and comment

[Ted Dennison]

In article <9kacr0$l8o$1@news.service.uci.edu>, Navid Azimi says...
>
>What about putting links or information about how to -start- programming in
>Ada? I'm more confused on how to get it, say a simple hello world, running
>as opposed to problems with strings and arrays. I dont know which
>program/compiler to download, or what extension I need on my file, or
>anything simple of that sorts.
..
>PS. I'm on Win 98 SE

Well, that stuff isn't in the standard (note: there's nothing in the C standard
that forces .c and .h either, and I've seen some programs that use other
extensions). Its all compiler specific. So what you really need to know is:

1) Where to get a compiler for Win98
2) How to create a small program with that compiler

2 is going to have to come from your compiler docs. 1 depends on how much you
want to pay. If you want a no-cost compiler there are two for that platform, see
the "Free Ada Compilers" heading at http://www.adapower.com/links.html . The
free ObjectAda is sort of cripple-ware for a (somewhare around $500 if I
remember) version. That compiler may be what you want though, if you would
prefer a VisualStudio-style interface, along with integrated GUI development
tools. Gnat is a full industrial-strength Ada compiler, but uses the more
professional Emacs environment as its IDE.

Also, I suggest you look at http://www.geocities.com/win4ada/ (a website written
by a fellow Win98 Ada newbie), and keep http://www.adapower.com bookmarked.

---
T.E.D.    homepage   - http://www.telepath.com/dennison/Ted/TED.html
          home email - mailto:dennison@telepath.com