output-stream-p Generic Function

Summary

A generic function that determines if an object is an output stream.

Package

common-lisp

Signature

output-stream-p stream => result

Arguments

stream⇩

A stream.

Values

result

A generalized boolean.

Description

The generic function output-stream-p implements the standard function. There are methods with stream specialized on fundamental-stream, fundamental-input-stream and fundamental-output-stream that returns t if stream is an output stream. If you want to implement a stream class with no inherent directionality (and thus does not inherit from fundamental-input-stream or fundamental-output-stream) but for which the directionality depends on the instance, then you should add specialized method for output-stream-p.

Examples

There is an example in 24.2.3 Stream directionality.

See also

output-stream-p in the Common Lisp HyperSpec
fundamental-output-stream
input-stream-p