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diff --git a/doc/fconfigure.n b/doc/fconfigure.n new file mode 100644 index 0000000..550d071 --- /dev/null +++ b/doc/fconfigure.n @@ -0,0 +1,289 @@ +'\" +'\" Copyright (c) 1995-1996 Sun Microsystems, Inc. +'\" +'\" See the file "license.terms" for information on usage and redistribution +'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. +'\" +.so man.macros +.TH fconfigure n 8.3 Tcl "Tcl Built-In Commands" +.BS +'\" Note: do not modify the .SH NAME line immediately below! +.SH NAME +fconfigure \- Set and get options on a channel +.SH SYNOPSIS +.nf +\fBfconfigure \fIchannelId\fR +\fBfconfigure \fIchannelId\fR \fIname\fR +\fBfconfigure \fIchannelId\fR \fIname value \fR?\fIname value ...\fR? +.fi +.BE +.SH DESCRIPTION +.PP +The \fBfconfigure\fR command sets and retrieves options for channels. +.PP +\fIChannelId\fR identifies the channel for which to set or query an +option and must refer to an open channel such as a Tcl standard +channel (\fBstdin\fR, \fBstdout\fR, or \fBstderr\fR), the return +value from an invocation of \fBopen\fR or \fBsocket\fR, or the result +of a channel creation command provided by a Tcl extension. +.PP +If no \fIname\fR or \fIvalue\fR arguments are supplied, the command +returns a list containing alternating option names and values for the channel. +If \fIname\fR is supplied but no \fIvalue\fR then the command returns +the current value of the given option. +If one or more pairs of \fIname\fR and \fIvalue\fR are supplied, the +command sets each of the named options to the corresponding \fIvalue\fR; +in this case the return value is an empty string. +.PP +The options described below are supported for all channels. In addition, +each channel type may add options that only it supports. See the manual +entry for the command that creates each type of channels for the options +that that specific type of channel supports. For example, see the manual +entry for the \fBsocket\fR command for additional options for sockets, and +the \fBopen\fR command for additional options for serial devices. +.TP +\fB\-blocking\fR \fIboolean\fR +The \fB\-blocking\fR option determines whether I/O operations on the +channel can cause the process to block indefinitely. +The value of the option must be a proper boolean value. +Channels are normally in blocking mode; if a channel is placed into +nonblocking mode it will affect the operation of the \fBgets\fR, +\fBread\fR, \fBputs\fR, \fBflush\fR, and \fBclose\fR commands by +allowing them to operate asynchronously; +see the documentation for those commands for details. +For nonblocking mode to work correctly, the application must be +using the Tcl event loop (e.g. by calling \fBTcl_DoOneEvent\fR or +invoking the \fBvwait\fR command). +.TP +\fB\-buffering\fR \fInewValue\fR +. +If \fInewValue\fR is \fBfull\fR then the I/O system will buffer output +until its internal buffer is full or until the \fBflush\fR command is +invoked. If \fInewValue\fR is \fBline\fR, then the I/O system will +automatically flush output for the channel whenever a newline character +is output. If \fInewValue\fR is \fBnone\fR, the I/O system will flush +automatically after every output operation. The default is for +\fB\-buffering\fR to be set to \fBfull\fR except for channels that +connect to terminal-like devices; for these channels the initial setting +is \fBline\fR. Additionally, \fBstdin\fR and \fBstdout\fR are +initially set to \fBline\fR, and \fBstderr\fR is set to \fBnone\fR. +.TP +\fB\-buffersize\fR \fInewSize\fR +. +\fINewvalue\fR must be an integer; its value is used to set the size of +buffers, in bytes, subsequently allocated for this channel to store input +or output. \fINewvalue\fR must be between one and one million, allowing +buffers of one to one million bytes in size. +.TP +\fB\-encoding\fR \fIname\fR +. +This option is used to specify the encoding of the channel, so that the data +can be converted to and from Unicode for use in Tcl. For instance, in +order for Tcl to read characters from a Japanese file in \fBshiftjis\fR +and properly process and display the contents, the encoding would be set +to \fBshiftjis\fR. Thereafter, when reading from the channel, the bytes in +the Japanese file would be converted to Unicode as they are read. +Writing is also supported \- as Tcl strings are written to the channel they +will automatically be converted to the specified encoding on output. +.RS +.PP +If a file contains pure binary data (for instance, a JPEG image), the +encoding for the channel should be configured to be \fBbinary\fR. Tcl +will then assign no interpretation to the data in the file and simply read or +write raw bytes. The Tcl \fBbinary\fR command can be used to manipulate this +byte-oriented data. It is usually better to set the +\fB\-translation\fR option to \fBbinary\fR when you want to transfer +binary data, as this turns off the other automatic interpretations of +the bytes in the stream as well. +.PP +The default encoding for newly opened channels is the same platform- and +locale-dependent system encoding used for interfacing with the operating +system, as returned by \fBencoding system\fR. +.RE +.TP +\fB\-eofchar\fR \fIchar\fR +.TP +\fB\-eofchar\fR \fB{\fIinChar outChar\fB}\fR +. +This option supports DOS file systems that use Control-z (\ex1a) as an +end of file marker. If \fIchar\fR is not an empty string, then this +character signals end-of-file when it is encountered during input. For +output, the end-of-file character is output when the channel is closed. +If \fIchar\fR is the empty string, then there is no special end of file +character marker. For read-write channels, a two-element list specifies +the end of file marker for input and output, respectively. As a +convenience, when setting the end-of-file character for a read-write +channel you can specify a single value that will apply to both reading +and writing. When querying the end-of-file character of a read-write +channel, a two-element list will always be returned. The default value +for \fB\-eofchar\fR is the empty string in all cases except for files +under Windows. In that case the \fB\-eofchar\fR is Control-z (\ex1a) for +reading and the empty string for writing. +The acceptable range for \fB\-eofchar\fR values is \ex01 - \ex7f; +attempting to set \fB\-eofchar\fR to a value outside of this range will +generate an error. +.TP +\fB\-translation\fR \fImode\fR +.TP +\fB\-translation\fR \fB{\fIinMode outMode\fB}\fR +. +In Tcl scripts the end of a line is always represented using a single +newline character (\en). However, in actual files and devices the end of +a line may be represented differently on different platforms, or even for +different devices on the same platform. For example, under UNIX newlines +are used in files, whereas carriage-return-linefeed sequences are +normally used in network connections. On input (i.e., with \fBgets\fR +and \fBread\fR) the Tcl I/O system automatically translates the external +end-of-line representation into newline characters. Upon output (i.e., +with \fBputs\fR), the I/O system translates newlines to the external +end-of-line representation. The default translation mode, \fBauto\fR, +handles all the common cases automatically, but the \fB\-translation\fR +option provides explicit control over the end of line translations. +.RS +.PP +The value associated with \fB\-translation\fR is a single item for +read-only and write-only channels. The value is a two-element list for +read-write channels; the read translation mode is the first element of +the list, and the write translation mode is the second element. As a +convenience, when setting the translation mode for a read-write channel +you can specify a single value that will apply to both reading and +writing. When querying the translation mode of a read-write channel, a +two-element list will always be returned. The following values are +currently supported: +.TP +\fBauto\fR +. +As the input translation mode, \fBauto\fR treats any of newline +(\fBlf\fR), carriage return (\fBcr\fR), or carriage return followed by a +newline (\fBcrlf\fR) as the end of line representation. The end of line +representation can even change from line-to-line, and all cases are +translated to a newline. As the output translation mode, \fBauto\fR +chooses a platform specific representation; for sockets on all platforms +Tcl chooses \fBcrlf\fR, for all Unix flavors, it chooses \fBlf\fR, and +for the various flavors of Windows it chooses \fBcrlf\fR. The default +setting for \fB\-translation\fR is \fBauto\fR for both input and output. +.TP +\fBbinary\fR +. +No end-of-line translations are performed. This is nearly identical to +\fBlf\fR mode, except that in addition \fBbinary\fR mode also sets the +end-of-file character to the empty string (which disables it) and sets the +encoding to \fBbinary\fR (which disables encoding filtering). See the +description of \fB\-eofchar\fR and \fB\-encoding\fR for more information. +.RS +.PP +Internally, i.e. when it comes to the actual behaviour of the +translator this value \fBis\fR identical to \fBlf\fR and is therefore +reported as such when queried. Even if \fBbinary\fR was used to set +the translation. +.RE +.TP +\fBcr\fR +. +The end of a line in the underlying file or device is represented by a +single carriage return character. As the input translation mode, +\fBcr\fR mode converts carriage returns to newline characters. As the +output translation mode, \fBcr\fR mode translates newline characters to +carriage returns. +.TP +\fBcrlf\fR +. +The end of a line in the underlying file or device is represented by a +carriage return character followed by a linefeed character. As the input +translation mode, \fBcrlf\fR mode converts carriage-return-linefeed +sequences to newline characters. As the output translation mode, +\fBcrlf\fR mode translates newline characters to carriage-return-linefeed +sequences. This mode is typically used on Windows platforms and for +network connections. +.TP +\fBlf\fR +. +The end of a line in the underlying file or device is represented by a +single newline (linefeed) character. In this mode no translations occur +during either input or output. This mode is typically used on UNIX +platforms. +.RE +.PP +.SH "STANDARD CHANNELS" +.PP +The Tcl standard channels (\fBstdin\fR, \fBstdout\fR, and \fBstderr\fR) +can be configured through this command like every other channel opened +by the Tcl library. Beyond the standard options described above they +will also support any special option according to their current type. +If, for example, a Tcl application is started by the \fBinet\fR +super-server common on Unix system its Tcl standard channels will be +sockets and thus support the socket options. +.SH EXAMPLES +.PP +Instruct Tcl to always send output to \fBstdout\fR immediately, +whether or not it is to a terminal: +.PP +.CS +\fBfconfigure\fR stdout -buffering none +.CE +.PP +Open a socket and read lines from it without ever blocking the +processing of other events: +.PP +.CS +set s [socket some.where.com 12345] +\fBfconfigure\fR $s -blocking 0 +fileevent $s readable "readMe $s" +proc readMe chan { + if {[gets $chan line] < 0} { + if {[eof $chan]} { + close $chan + return + } + # Could not read a complete line this time; Tcl's + # internal buffering will hold the partial line for us + # until some more data is available over the socket. + } else { + puts stdout $line + } +} +.CE +.PP +Read a PPM-format image from a file: +.PP +.CS +# Open the file and put it into Unix ASCII mode +set f [open teapot.ppm] +\fBfconfigure\fR $f \-encoding ascii \-translation lf + +# Get the header +if {[gets $f] ne "P6"} { + error "not a raw\-bits PPM" +} + +# Read lines until we have got non-comment lines +# that supply us with three decimal values. +set words {} +while {[llength $words] < 3} { + gets $f line + if {[string match "#*" $line]} continue + lappend words {*}[join [scan $line %d%d%d]] +} + +# Those words supply the size of the image and its +# overall depth per channel. Assign to variables. +lassign $words xSize ySize depth + +# Now switch to binary mode to pull in the data, +# one byte per channel (red,green,blue) per pixel. +\fBfconfigure\fR $f \-translation binary +set numDataBytes [expr {3 * $xSize * $ySize}] +set data [read $f $numDataBytes] + +close $f +.CE +.SH "SEE ALSO" +close(n), flush(n), gets(n), open(n), puts(n), read(n), socket(n), +Tcl_StandardChannels(3) +.SH KEYWORDS +blocking, buffering, carriage return, end of line, flushing, linemode, +newline, nonblocking, platform, translation, encoding, filter, byte array, +binary +'\" Local Variables: +'\" mode: nroff +'\" End: |