PR# 2681 Problem with preconditions of read_character, read_integer, etc in FILE.

There seems to be a problem with the preconditions of the read_character, 
read_integer, etc features in FILE. The problem occurs when you inadvertently 
attempt to read a file that has been opened only for writing. You would expect 
the precondition to detect the error, but it doesn't. Instead, it fails 
later with an I/O error.

Possible solution: In FILE, rename 'readable' from IO_MEDIUM as 'file_readable', then remove the 'require else' clauses from 'read_x' features.

See attached file for more detailed description.

	make is
		local
			f: PLAIN_TEXT_FILE
		do
			create f.make_open_write ("f.txt")
			f.put_string ("abc")
			f.read_character
			io.put_character (f.last_character)
		end

From: "Gerry Butler" <gbutler@dstc.monash.edu.au>
To: <bugs@support.eiffel.com>
Cc:  Subject: RE: EiffelBase/2681
Date: Wed, 11 Oct 2000 09:34:51 +1000

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 Good morning
 
 I think I forgot to include the attachment with my original bug report.
 
 Here it is.
 
 Gerry
 
 
 
 
 
 
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 	filename="read_x_precondition.txt"
 
 There seems to be a problem with the preconditions of the =
 read_character,=20
 read_integer, etc features in FILE. The problem occurs when you =
 inadvertently=20
 attempt to read a file that has been opened only for writing. You would =
 expect=20
 the precondition to detect the error, but it doesn't. Instead, it fails=20
 later with an I/
....
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