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From: "Robert I. Eachus" <eachus@mitre.org>
Subject: Re: Ada vs Delphi?
Date: 1999/08/17
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Newsgroups: comp.lang.ada
Date: 1999-08-17T22:58:22+00:00
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Andre Ratel wrote:
  
> But how do you avoid complex expressions becoming cumbersome?
 
    By defining the operators you need so that the code makes sense. 
For example:

  function Clock return Tick;
  type Tick is new Integer; -- lets assume a 1 millisecond clock.
  type Seconds is delta 0.001 digits 6; -- let's use a decimal type for
kicks.
  type Minutes is range -186400..186399;
  ...
  function "+" (L: Tick; R: Seconds) return Seconds;
  function "+" (L: Tick; R: Seconds) return Tick;
  pragma Inline("+"); -- applies to both functions.
  ...
  function "+" (L: Tick; R: Seconds) return Seconds is
  begin return Seconds(L)/1000 + R; end "+";
  function "+" (L: Tick; R: Seconds) return Tick is 
  begin return L + Tick(R * 1000); end "+";

  Now you can write:

    Total_Waiting_Time: Seconds := 0.0;
  ...
  function Something;
    Now: Tick := Clock;
  begin -- waiting ;-)
    Acquire_Lock;
    Actually_Do_Something;
    Release_Lock;
    Total_Waiting_Time := Total_Waiting_Time + Clock - Now;
  end;  
  
  Of course, this is all expository.  You don't want to do that, even
when you are writing a simulation package because the language provides
two time packages (Ada.Calendar and Ada.Real_Time) plus a type
Standard.Duration with many types and conversions already defined.  (In
addition if you use a predefined time type, you can use it in delay and
delay until statements.)

-- 

                                        Robert I. Eachus

with Standard_Disclaimer;
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function Message (Text: in Clever_Ideas) return Better_Ideas is...