58 lines
2.3 KiB
Racket
58 lines
2.3 KiB
Racket
#lang scribble/doc
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@(require "mz.ss")
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@title[#:tag "port-ops"]{Managing Ports}
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@defproc[(input-port? [v any/c]) boolean?]{
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Returns @scheme[#t] if @scheme[v] is an input port, @scheme[#f] otherwise.}
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@defproc[(output-port? [v any/c]) boolean?]{
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Returns @scheme[#t] if @scheme[v] is an output port, @scheme[#f] otherwise.}
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@defproc[(port? [v any/c]) boolean?]{
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Returns @scheme[#t] if either @scheme[(input-port? v)] or
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@scheme[(output-port? v)] is @scheme[#t], @scheme[#f] otherwise.}
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@defproc[(close-input-port [in input-port?]) void?]{
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Closes the input port @scheme[in]. For some kinds of ports, closing
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the port releases lower-level resources, such as a file handle. If
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the port is already closed, @scheme[close-input-port] has no effect.}
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@defproc[(close-output-port [out output-port?]) void?]{
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Closes the output port @scheme[out]. For some kinds of ports, closing
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the port releases lower-level resources, such as a file handle. Also,
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if the port is buffered, closing may first flush the port before
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closing it, and this flushing process can block. If the port is
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already closed, @scheme[close-output-port] has no effect.}
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@defproc[(port-closed? [port port?]) boolean?]{
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Returns @scheme[#t] if the input or output port @scheme[port] is
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closed, @scheme[#f] otherwise.}
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@defparam[current-input-port in input-port?]{A parameter that
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determines a default input port for many operations, such as
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@scheme[read].}
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@defparam[current-output-port out output-port?]{A parameter that
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determines a default output port for many operations, such as
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@scheme[write].}
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@defparam[current-error-port out output-port?]{A parameter that
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determines an output port that is typically used for errors and
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logging. For example, the default error display handler writes to this
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port.}
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@defproc[(file-stream-port? [port port?]) boolean?]{
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Returns @scheme[#t] if the given port is a @tech{file-stream port} (see
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@secref["file-ports"]), @scheme[#f] otherwise.}
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@defproc[(terminal-port? [port port?]) boolean?]{
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Returns @scheme[#t] if the given port is attached to an interactive
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terminal, @scheme[#f] otherwise.}
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@defthing[eof eof-object?]{A value (distinct from all other values)
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that represents an end-of-file.}
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@defproc[(eof-object? [a any/c]) boolean?]{Returns @scheme[#t] is
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@scheme[v] is @scheme[eof], @scheme[#f] otherwise.}
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