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From: Erik Margraf <erik.margraf@siemens.at>
Subject: Q: Protected types and entries (long)
Date: 1999/02/16
Message-ID: <36C98180.98296205@siemens.at>#1/1
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 14:33:17 GMT)
Organization: Siemens AG
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NNTP-Posting-Date: 16 Feb 1999 14:33:17 GMT
Newsgroups: comp.lang.ada
Date: 1999-02-16T14:33:17+00:00
List-Id: <comp.lang.ada>

Recently I started to learn about protected types. I tried to do =

something like the following:

(Not 100% Ada :-)

=2E..
   type buffer is array (...) of character;
   protected type Object is
     entry put (data : in buffer);
   private
     internal_buffer : array (BIG_Enough) of character;
     items_in_buffer : integer :=3D 0;
   end; =

=2E..
   protected Object body

   entry put (data : in buffer) =

	when data'size + items_in_buffer <=3D internal_buffer=B4size is
   begin
    ...
   end;
   end Object;

Since the reference to a formal parameter of an entry is not allowed,
gnat
refused to compile this ;-). I changed the code to

   type buffer is array (...) of character;
   protected type Object is
     entry put (data : in buffer);
   private
     entry p_put (data : in buffer);
     internal_buffer : array (BIG_Enough) of character;
     data_size : integer;
     items_in_buffer : integer :=3D 0;
   end; =

=2E..
   protected Object body
   entry put (data : in buffer) =

	when true is
   begin
      data_size :=3D data=B4size;
      if data_size + items_in_buffer > internal_buffer=B4size then =

        requeue p_put;
      end if;
   end;

   entry p_put (data : in buffer) =

	when data_size + items_in_buffer <=3D internal_buffer=B4size is
   begin
    ...
   end;
   end Object;

This compiles. =

Now my questions:

	- Can someone tell me WHY this limitation in the barrier exists?
	- Is my "solution" really a solution to this problem?
	- (What) Should I do something different?
Thanks

Erik Margraf

-- =

--------------------------------------------------------------------
-- Erik Margraf
-- Siemens Austria PSE KB2
-- erik.margraf@siemens.at
-- +43 1 1707 45887
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