From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00
	autolearn=unavailable autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!mx02.eternal-september.org!feeder.eternal-september.org!usenet.blueworldhosting.com!feeder01.blueworldhosting.com!peer01.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!post01.iad.highwinds-media.com!fx19.iad.POSTED!not-for-mail
From: Brad Moore <brad.moore@shaw.ca>
User-Agent: Mozilla/5.0 (X11; Linux x86_64;
 rv:31.0) Gecko/20100101 Thunderbird/31.3.0
MIME-Version: 1.0
Newsgroups: comp.lang.ada
Subject: Re: Any Suggestion How To Accomplish A Debug Macro?
References: <XJoow.967315$Lj7.45437@fx22.iad> <ly61ctqthv.fsf@pushface.org>
In-Reply-To: <ly61ctqthv.fsf@pushface.org>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Message-ID: <gCDow.832901$No4.618024@fx19.iad>
NNTP-Posting-Host: 68.145.219.148
X-Complaints-To: internet.abuse@sjrb.ca
X-Trace: 1419970060 68.145.219.148 (Tue, 30 Dec 2014 20:07:40 UTC)
NNTP-Posting-Date: Tue, 30 Dec 2014 20:07:40 UTC
Date: Tue, 30 Dec 2014 13:07:41 -0700
X-Received-Bytes: 2566
X-Received-Body-CRC: 198467052
Xref: news.eternal-september.org comp.lang.ada:24296
Date: 2014-12-30T13:07:41-07:00
List-Id: <comp.lang.ada>

On 14-12-30 04:14 AM, Simon Wright wrote:
> Hubert <herrdoktor@fumanchu.com> writes:
>
>> I know there is no such thing as C #define's in Ada, but isn't there a
>> way to make some sort of debug macro?
>> In my C++ code I use a lot of statements like
>>
>> PRINT(DEBUG_CHANNEL, "TEXT" );
>>
>> to print out debug messages and in release code, these defines aren't
>> compiled. Is there any way to achieve something like this in Ada
>> without surrounding it with an IF statement and a boolean flag?
>
> GNAT has pragma Debug[1]. I was always annoyed that this is controlled
> by -gnata, which also controls assertions, but I see there's a pragma
> Debug_Policy - stated to be equivalent to pragma Check_Policy (Debug).
>
> [1] https://gcc.gnu.org/onlinedocs/gnat_ugn_unw/Debugging---A-Special-Case.html
>


Another more portable solution would be to declare a static constant 
somewhere, and use the value of that constant to decide if logging 
should occur. If the compiler/linker supports dead code elimination, 
then the debug code can be eliminated if that variable is set to False.

Eg.

package Debug_Logging is
    Debug_Enabled : constant Boolean := False;  -- Edit this line
    procedure Log(Message : String);
end Debug_Logging;


with Debug_Logging;

procedure Foo is
begin
    -- if statement removed if Debug_Enabled is false
    if Debug_Enabled then
      Log("Entered Foo");
    end if;
end Foo;

This works in GNAT, and might work in other compilers as well. Worst 
case is that the Debug_Enabled boolean get evaluated in multiple places, 
but that overhead of evaluating a Boolean might still be acceptable for 
a compiler that doesn't do dead code elimination.

Brad