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From: Martin Krischik <krischik@users.sourceforge.net>
Newsgroups: comp.lang.ada
Subject: Re: and then... (a curiosity)
Date: Mon, 01 Sep 2008 10:05:57 +0200
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Maciej Sobczak schrieb:
> On 29 Sie, 23:47, Samuel Tardieu <s...@rfc1149.net> wrote:
> 
>> Sometimes, you want to ensure that both sides of the boolean operator
>> have been evaluated. Here is an example:
>>
>>   --  Send the message to the log and return True if it
>>   --  has been logged at least at one place succesfully.
>>
>>   function Log (Message : String) return Boolean is
>>   begin
>>      return Log_To_Network (Message) or Log_To_Disk (Message);
>>   end Log;
> 
> This is actually a bad example. It might use "or else" and still
> retain the semantics as described in the comment above.

Actually it is good example - for both:

1) Log to both Disk and Network and return true if at least one was
successful:

Log_To_Network (Message) or Log_To_Disk (Message)

2) Log to Network and if that fails log to Disk and return true if at
least one was successful:

Log_To_Network (Message) or else Log_To_Disk (Message)

And it shows nicely the why there are two: The programmer can decide
which behaviour he / she wants.

Martin

-- 
mailto://krischik@users.sourceforge.net
Ada programming at: http://ada.krischik.com