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       AnyFile  { built-in type }


AnyFile is a built-in type that can only be used for parameters and pointer targets. Any kind of file variable (Text, untyped and typed file) can be passed to such a parameter and their address assigned to such a pointer. On the other side, only generic file operations are possible with AnyFile parameters/pointer targets.

This type is useful for implementing generic file handling routines. Also some built-in file routines use this type for their parameters, e.g. IOSelectRead (see Run Time System).

BlockRead (see BlockRead) and BlockWrite (see BlockWrite) treat AnyFile specially, in that they accept all AnyFiles as arguments (even if the actual file is a typed or Text file) and always use a block size of 1 (even if the actual file is an untyped file with different block size or a typed file of a type with size not equal to one). This is the only way to reliably read/write a certain amount of data from/to an AnyFile.

AnyFile pointers cannot be allocated with New (because it would be unspecified which kind of file to create).

Conforming to

AnyFile is a GNU Pascal extension.


     program AnyFileDemo;
     procedure Test (var f: AnyFile);
     var v: ^AnyFile;
       { Generic file operations are allowed for `AnyFile' }
       Rewrite (f);
       { `AnyFile' can also be accessed via pointers }
       v := @f;
       Close (v^)
       t: Text;
       f: file;
       g: file of Integer;
       { Any kind of file variable can be passed as `AnyFile' }
       Test (t);
       Test (f);
       Test (g)

See also

Text, file.