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Re: Reading in cooked mode (was Re: Python MSI not installing, log file showing name of a Viatnemese communist revolutionary)

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On Sun, 23 Mar 2014 13:16:35 +1100, Cameron Simpson <cs@zip.com.au>
declaimed the following:

>As far as I'm concerned, a text file is a sequence lines, each of
>which is _terminated_ by a newline (or the OS end-of-line flavour).
>

	May I introduce you to Ada and the Text_IO package?

http://www.adahome.com/rm95/rm9x-A-10.html
"""
(7)
    From a logical point of view, a text file is a sequence of pages, a
page is a sequence of lines, and a line is a sequence of characters; the
end of a line is marked by a line terminator; the end of a page is marked
by the combination of a line terminator immediately followed by a page
terminator; and the end of a file is marked by the combination of a line
terminator immediately followed by a page terminator and then a file
terminator. Terminators are generated during output; either by calls of
procedures provided expressly for that purpose; or implicitly as part of
other operations, for example, when a bounded line length, a bounded page
length, or both, have been specified for a file. 
(8)
    The actual nature of terminators is not defined by the language and
hence depends on the implementation. Although terminators are recognized or
generated by certain of the procedures that follow, they are not
necessarily implemented as characters or as sequences of characters.
Whether they are characters (and if so which ones) in any particular
implementation need not concern a user who neither explicitly outputs nor
explicitly inputs control characters. The effect of input (Get) or output
(Put) of control characters (other than horizontal tabulation) is not
specified by the language. 
""" 
and
"""
(11)
    For an output file or an append file, a maximum line length can be
specified and a maximum page length can be specified. If a value to be
output cannot fit on the current line, for a specified maximum line length,
then a new line is automatically started before the value is output; if,
further, this new line cannot fit on the current page, for a specified
maximum page length, then a new page is automatically started before the
value is output. Functions are provided to determine the maximum line
length and the maximum page length. When a file is opened with mode
Out_File or Append_File, both values are zero: by convention, this means
that the line lengths and page lengths are unbounded. (Consequently, output
consists of a single line if the subprograms for explicit control of line
and page structure are not used.) The constant Unbounded is provided for
this purpose. 
"""

	In particular, point (8). The implementation is free to use a form
where each "line" is preceded by a length value. Might be more complicated
to handle in piecemeal I/O as the entire "line" needs to be buffered until
complete and a length is known.

>
>Plenty of people use editors that consider end-of-line to be a
>separator and not a terminator, leading to supposed text files
>lacking trailing newlines (or end-of-line of OS).
>

	Also note that point (7) implies that even if one is using
control-characters as terminators, a valid text file ends with
<newline><newpage><end-of-file> 

	What does that do to your editor? <G>
-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/

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Re: Reading in cooked mode (was Re: Python MSI not installing, log file showing name of a Viatnemese communist revolutionary) Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-03-23 10:37 -0400

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