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A ptob is a port object, capable of delivering or accepting characters. See Ports in Revised(5) Report on the Algorithmic Language Scheme. Unlike the types described so far, new varieties of ptobs can be defined dynamically (see Defining Ptobs). These are the initial ptobs:
input port.
output port.
input-output port.
input pipe created by popen()
.
output pipe created by popen()
.
String port created by cwos()
or cwis()
.
Software (virtual) port created by mksfpt()
(see Soft Ports).
Returns non-zero if x is a port, open port, open input-port, open output-port, input-port, or output-port, respectively.
Returns non-zero if port x is open or closed, respectively.
Returns the FILE *
stream for port x.
Ports which are particularly well behaved are called fports.
Advanced operations like file-position
and reopen-file
only work for fports.
Returns non-zero if x is a port, open port, open input-port, or open output-port, respectively.