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 pipe created by
output pipe created by
String port created by
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.
FILE * stream for port x.
Ports which are particularly well behaved are called fports.
Advanced operations like
only work for fports.
Returns non-zero if x is a port, open port, open input-port, or open output-port, respectively.