11.43 srfi.192 - Port positioning

Module: srfi.192 ¶

This srfi defines procedures to get and set the current position of the port.

This feature is already supported in the Gauche core, so the following procedure is described in Common port operations.

port-position
port-has-port-position?
set-port-position!
port-has-set-port-position?

Function: make-i/o-invalid-position-error pos ¶

[SRFI-192]{srfi.192} This portably creates a condition suitable to be raised from set-port-position! when the given position object can’t be accepted. The pos argument is the offending position object.

In Gauche, such condition is represented by <io-invalid-position-error> class, which is a subclass of <port-error>.

If you raise a condition created with this procedure from the set-position! callback of the custom ports (see srfi.181 - Custom ports), Gauche intercepts it and adds the port information to the condition.

Function: i/o-invalid-position-error? obj ¶

[SRFI-192]{srfi.192} Returns #t iff obj is an i/o-invalid-position-error condition (or a compound condition that includes it).

In Gauche, it is the same as (condition-has-type? obj <io-invalid-position-error>).