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A.10.2 Text File Management
Static Semantics
1
The only allowed
file modes for text files are the modes In_File, Out_File, and Append_File.
The subprograms given in subclause
A.8.2
for the control of external files, and the function End_Of_File given
in subclause
A.8.3 for sequential input-output,
are also available for text files. There is also a version of End_Of_File
that refers to the current default input file. For text files, the procedures
have the following additional effects:
2
- For the procedures Create and Open:
After a file with mode Out_File or Append_File is opened, the page length
and line length are unbounded (both have the conventional value zero).
After a file (of any mode) is opened, the current column, current line,
and current page numbers are set to one. If the mode is Append_File,
it is implementation defined whether a page terminator will separate
preexisting text in the file from the new text to be written.
3
- For the procedure Close: If the file
has the current mode Out_File or Append_File, has the effect of calling
New_Page, unless the current page is already terminated; then outputs
a file terminator.
4
- For the procedure Reset: If the file
has the current mode Out_File or Append_File, has the effect of calling
New_Page, unless the current page is already terminated; then outputs
a file terminator. The current column, line, and page numbers are set
to one, and the line and page lengths to Unbounded. If the new mode is
Append_File, it is implementation defined whether a page terminator will
separate preexisting text in the file from the new text to be written.
5
The exception Mode_Error is propagated by the
procedure Reset upon an attempt to change the mode of a file that is
the current default input file, the current default output file, or the
current default error file.
6
22 An
implementation can define the Form parameter of Create and Open to control
effects including the following:
7
- the interpretation
of line and column numbers for an interactive file, and
8
- the interpretation
of text formats in a file created by a foreign program.
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