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From: Stephen Leake <Stephen.Leake@gsfc.nasa.gov>
Subject: Re: help on task types
Date: 1999/03/03
Message-ID: <u678i8bv8.fsf@gsfc.nasa.gov>#1/1
X-Deja-AN: 450917425
References: <36DD8EBF.EAA@rmcs.cranfield.ac.uk>
Organization: NASA Goddard Space Flight Center -- Greenbelt, Maryland USA
Newsgroups: comp.lang.ada
Date: 1999-03-03T00:00:00+00:00
List-Id: <comp.lang.ada>

coxaw <coxaw@rmcs.cranfield.ac.uk> writes:

> If I declare a task type that reads input from a file and prints to
> screen
> 
> Then instantiate 3 copies of this type
> 
> can i tell each one to read from a different file ?
> 
> and how is it done ?
> 
> ie
> 
> task type reader_type is
> blah
> blah
> blah
> end reader;
> 
> read1:reader_type;
> read2:reader_type;
> 
> but read1 is to read from inFile1
> and read2 from inFile2

One way is to use a discriminant:

task type reader_type (File_Name : access String) is
...
end reader_type;

File_Name_1 : aliased constant String := "inFile1";
read1 : reader_type (File_Name_1'access);

Discriminants must be scalars, so you can't put a string there directly.

Another way is to pass the file name to the task via an Initialize
entry:

task type reader_type is
    entry Initialize (File_Name : in String);
end reader_type;

This requires the user to call Initialize, which is usually a pain. But
you can pass more complex stuff that way, than with a discriminant.

-- Stephe