VAX Ada sequential IO and Direct IO

VAX Ada sequential IO and Direct IO

[alden]

Has anyone had problems with VAX Ada sequential_io and direct_IO when
instantiated with a discriminated record type which has an unconstrained
component.  I keep getting use_error raised when doing a create or open.

example


type foo(a : integer) is
	record
	   f1 : string(1..a);
	end record;

even if I restrict the range of 'a' by using a subtype of integer, or
create an integer type with a restricted range I still get a use_error.
In addition to the use error, an RMS error is listed as max record size 
exceeded.

	... Tony Alden
	(TRW)

Re: VAX Ada sequential IO and Direct IO

[gary]

> Has anyone had problems with VAX Ada sequential_io and direct_IO when
> instantiated with a discriminated record type which has an unconstrained
> component.  I keep getting use_error raised when doing a create or open.
> 
> example
> 
> 
> type foo(a : integer) is
> 	record
> 	   f1 : string(1..a);
> 	end record;
> 
> even if I restrict the range of 'a' by using a subtype of integer, or
> create an integer type with a restricted range I still get a use_error.
> In addition to the use error, an RMS error is listed as max record size 
> exceeded.
> 
> 	... Tony Alden
> 	(TRW)
> 
> 
We've been able to use sequential and direct io with discrimant
records successfully by specifying a default discriminant value,
i.e. the records have to be "constrained" at time of
instantiation of io package.

	You might try something like the following:

  type foo(a : integer := MAXLENGTH) is
  	record
  	   f1 : string(1..a);
  	end record;
  
  package rec_io is new sequential_io(foo);


	Good Luck,

				Gary Gafke
				gary@aplpy.arpa
			or	seismo!mimsy!aplcen!gary
			or	(301) 953-6999