Re: Disabling string evaluation in a logging system

["(see below)" <yaldnif.w@blueyonder.co.uk>]

On 19/05/2010 13:38, in article 1p3xrphlq60da.1cq62wm0ajal2$.dlg@40tude.net,
"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote:

> On Wed, 19 May 2010 05:04:32 -0400, Stephen Leake wrote:
> 
>> dhenry <tfc.duke@gmail.com> writes:
>> 
>>> As Dmitry said, the log level may dynamically change. Therefore,
>>> inlining in order to let the compiler do the optimization doesn't
>>> work.
>> 
>> I don't follow this. Inlining is the same as writing the if-test.
> 
> That depends on the compiler.
> 
> procedure Log (Barrier : Boolean; Message : String) is
> begin
>    if Barrier then
>       Put (Message);
>    end if;
> end Log;
> 
> can be inlined as:
> 
> 1. moving evaluation of temporaries down:
> 
>    declare
>       Barrier : constant Boolean := <condition-expression>;
>    begin
>       if Barrier then
>          declare
>             Message : constant String := <message-expression>;
>          begin
>             Put (Message);
>          end;
>       end if;
>    end;
> 
> or as
> 
> 2. moving evaluation of temporaries up:
> 
>    declare
>       Barrier : constant Boolean := <condition-expression>;
>       Message : constant String := <message-expression>;
>    begin
>       if Barrier then
>         Put (Message);
>       end if;
>    end;
> 
> The language mandates nothing regarding this. The compiler can even ignore
> the pragma Inline.

I thought the second would be required, to allow side effects to take place
as they would normally.

-- 
Bill Findlay
<surname><forename> chez blueyonder.co.uk