6.1.6 Ptob Cells

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:

ptob: tc16_inport

input port.

ptob: tc16_outport

output port.

ptob: tc16_ioport

input-output port.

ptob: tc16_inpipe

input pipe created by popen().

ptob: tc16_outpipe

output pipe created by popen().

ptob: tc16_strport

String port created by cwos() or cwis().

ptob: tc16_sfport

Software (virtual) port created by mksfpt() (see Soft Ports).

Macro: PORTP x

Macro: OPPORTP x

Macro: OPINPORTP x

Macro: OPOUTPORTP x

Macro: INPORTP x

Macro: OUTPORTP x

Returns non-zero if x is a port, open port, open input-port, open output-port, input-port, or output-port, respectively.

Macro: OPENP x

Macro: CLOSEDP x

Returns non-zero if port x is open or closed, respectively.

Macro: STREAM x

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.

Macro: FPORTP x

Macro: OPFPORTP x

Macro: OPINFPORTP x

Macro: OPOUTFPORTP x

Returns non-zero if x is a port, open port, open input-port, or open output-port, respectively.