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| author | Shashank | 2017-05-29 12:40:26 +0530 |
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| committer | Shashank | 2017-05-29 12:40:26 +0530 |
| commit | 0345245e860375a32c9a437c4a9d9cae807134e9 (patch) | |
| tree | ad51ecbfa7bcd3cc5f09834f1bb8c08feaa526a4 /usr/man/mann/refchan.n | |
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diff --git a/usr/man/mann/refchan.n b/usr/man/mann/refchan.n new file mode 100755 index 000000000..6fa08483e --- /dev/null +++ b/usr/man/mann/refchan.n @@ -0,0 +1,606 @@ +'\" +'\" Copyright (c) 2006 Andreas Kupries <andreas_kupries@users.sourceforge.net> +'\" +'\" See the file "license.terms" for information on usage and redistribution +'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. +'\" +.\" The -*- nroff -*- definitions below are for supplemental macros used +.\" in Tcl/Tk manual entries. +.\" +.\" .AP type name in/out ?indent? +.\" Start paragraph describing an argument to a library procedure. +.\" type is type of argument (int, etc.), in/out is either "in", "out", +.\" or "in/out" to describe whether procedure reads or modifies arg, +.\" and indent is equivalent to second arg of .IP (shouldn't ever be +.\" needed; use .AS below instead) +.\" +.\" .AS ?type? ?name? +.\" Give maximum sizes of arguments for setting tab stops. Type and +.\" name are examples of largest possible arguments that will be passed +.\" to .AP later. If args are omitted, default tab stops are used. +.\" +.\" .BS +.\" Start box enclosure. From here until next .BE, everything will be +.\" enclosed in one large box. +.\" +.\" .BE +.\" End of box enclosure. +.\" +.\" .CS +.\" Begin code excerpt. +.\" +.\" .CE +.\" End code excerpt. +.\" +.\" .VS ?version? ?br? +.\" Begin vertical sidebar, for use in marking newly-changed parts +.\" of man pages. The first argument is ignored and used for recording +.\" the version when the .VS was added, so that the sidebars can be +.\" found and removed when they reach a certain age. If another argument +.\" is present, then a line break is forced before starting the sidebar. +.\" +.\" .VE +.\" End of vertical sidebar. +.\" +.\" .DS +.\" Begin an indented unfilled display. +.\" +.\" .DE +.\" End of indented unfilled display. +.\" +.\" .SO ?manpage? +.\" Start of list of standard options for a Tk widget. The manpage +.\" argument defines where to look up the standard options; if +.\" omitted, defaults to "options". The options follow on successive +.\" lines, in three columns separated by tabs. +.\" +.\" .SE +.\" End of list of standard options for a Tk widget. +.\" +.\" .OP cmdName dbName dbClass +.\" Start of description of a specific option. cmdName gives the +.\" option's name as specified in the class command, dbName gives +.\" the option's name in the option database, and dbClass gives +.\" the option's class in the option database. +.\" +.\" .UL arg1 arg2 +.\" Print arg1 underlined, then print arg2 normally. +.\" +.\" .QW arg1 ?arg2? +.\" Print arg1 in quotes, then arg2 normally (for trailing punctuation). +.\" +.\" .PQ arg1 ?arg2? +.\" Print an open parenthesis, arg1 in quotes, then arg2 normally +.\" (for trailing punctuation) and then a closing parenthesis. +.\" +.\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages. +.if t .wh -1.3i ^B +.nr ^l \n(.l +.ad b +.\" # Start an argument description +.de AP +.ie !"\\$4"" .TP \\$4 +.el \{\ +. ie !"\\$2"" .TP \\n()Cu +. el .TP 15 +.\} +.ta \\n()Au \\n()Bu +.ie !"\\$3"" \{\ +\&\\$1 \\fI\\$2\\fP (\\$3) +.\".b +.\} +.el \{\ +.br +.ie !"\\$2"" \{\ +\&\\$1 \\fI\\$2\\fP +.\} +.el \{\ +\&\\fI\\$1\\fP +.\} +.\} +.. +.\" # define tabbing values for .AP +.de AS +.nr )A 10n +.if !"\\$1"" .nr )A \\w'\\$1'u+3n +.nr )B \\n()Au+15n +.\" +.if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n +.nr )C \\n()Bu+\\w'(in/out)'u+2n +.. +.AS Tcl_Interp Tcl_CreateInterp in/out +.\" # BS - start boxed text +.\" # ^y = starting y location +.\" # ^b = 1 +.de BS +.br +.mk ^y +.nr ^b 1u +.if n .nf +.if n .ti 0 +.if n \l'\\n(.lu\(ul' +.if n .fi +.. +.\" # BE - end boxed text (draw box now) +.de BE +.nf +.ti 0 +.mk ^t +.ie n \l'\\n(^lu\(ul' +.el \{\ +.\" Draw four-sided box normally, but don't draw top of +.\" box if the box started on an earlier page. +.ie !\\n(^b-1 \{\ +\h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' +.\} +.el \}\ +\h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' +.\} +.\} +.fi +.br +.nr ^b 0 +.. +.\" # VS - start vertical sidebar +.\" # ^Y = starting y location +.\" # ^v = 1 (for troff; for nroff this doesn't matter) +.de VS +.if !"\\$2"" .br +.mk ^Y +.ie n 'mc \s12\(br\s0 +.el .nr ^v 1u +.. +.\" # VE - end of vertical sidebar +.de VE +.ie n 'mc +.el \{\ +.ev 2 +.nf +.ti 0 +.mk ^t +\h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n' +.sp -1 +.fi +.ev +.\} +.nr ^v 0 +.. +.\" # Special macro to handle page bottom: finish off current +.\" # box/sidebar if in box/sidebar mode, then invoked standard +.\" # page bottom macro. +.de ^B +.ev 2 +'ti 0 +'nf +.mk ^t +.if \\n(^b \{\ +.\" Draw three-sided box if this is the box's first page, +.\" draw two sides but no top otherwise. +.ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c +.el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c +.\} +.if \\n(^v \{\ +.nr ^x \\n(^tu+1v-\\n(^Yu +\kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c +.\} +.bp +'fi +.ev +.if \\n(^b \{\ +.mk ^y +.nr ^b 2 +.\} +.if \\n(^v \{\ +.mk ^Y +.\} +.. +.\" # DS - begin display +.de DS +.RS +.nf +.sp +.. +.\" # DE - end display +.de DE +.fi +.RE +.sp +.. +.\" # SO - start of list of standard options +.de SO +'ie '\\$1'' .ds So \\fBoptions\\fR +'el .ds So \\fB\\$1\\fR +.SH "STANDARD OPTIONS" +.LP +.nf +.ta 5.5c 11c +.ft B +.. +.\" # SE - end of list of standard options +.de SE +.fi +.ft R +.LP +See the \\*(So manual entry for details on the standard options. +.. +.\" # OP - start of full description for a single option +.de OP +.LP +.nf +.ta 4c +Command-Line Name: \\fB\\$1\\fR +Database Name: \\fB\\$2\\fR +Database Class: \\fB\\$3\\fR +.fi +.IP +.. +.\" # CS - begin code excerpt +.de CS +.RS +.nf +.ta .25i .5i .75i 1i +.. +.\" # CE - end code excerpt +.de CE +.fi +.RE +.. +.\" # UL - underline word +.de UL +\\$1\l'|0\(ul'\\$2 +.. +.\" # QW - apply quotation marks to word +.de QW +.ie '\\*(lq'"' ``\\$1''\\$2 +.\"" fix emacs highlighting +.el \\*(lq\\$1\\*(rq\\$2 +.. +.\" # PQ - apply parens and quotation marks to word +.de PQ +.ie '\\*(lq'"' (``\\$1''\\$2)\\$3 +.\"" fix emacs highlighting +.el (\\*(lq\\$1\\*(rq\\$2)\\$3 +.. +.\" # QR - quoted range +.de QR +.ie '\\*(lq'"' ``\\$1''\\-``\\$2''\\$3 +.\"" fix emacs highlighting +.el \\*(lq\\$1\\*(rq\\-\\*(lq\\$2\\*(rq\\$3 +.. +.\" # MT - "empty" string +.de MT +.QW "" +.. +.TH refchan n 8.5 Tcl "Tcl Built-In Commands" +.BS +.\" Note: do not modify the .SH NAME line immediately below! +.SH NAME +refchan \- Command handler API of reflected channels, version 1 +.SH SYNOPSIS +\fBcmdPrefix \fIoption\fR ?\fIarg arg ...\fR? +.BE +.SH DESCRIPTION +.PP +The Tcl-level handler for a reflected channel has to be a command with +subcommands (termed an \fIensemble\fR, as it is a command such as that +created by \fBnamespace ensemble create\fR, though the implementation +of handlers for reflected channel \fIis not\fR tied to \fBnamespace +ensemble\fRs in any way). Note that \fIcmdPrefix\fR is whatever was +specified in the call to \fBchan create\fR, and may consist of +multiple arguments; this will be expanded to multiple words in place +of the prefix. +.PP +Of all the possible subcommands, the handler \fImust\fR support +\fBinitialize\fR, \fBfinalize\fR, and \fBwatch\fR. Support for the +other subcommands is optional. +.SS "MANDATORY SUBCOMMANDS" +.TP +\fIcmdPrefix \fBinitialize \fIchannelId mode\fR +. +An invocation of this subcommand will be the first call the +\fIcmdPrefix\fR will receive for the specified new \fIchannelId\fR. It +is the responsibility of this subcommand to set up any internal data +structures required to keep track of the channel and its state. +.RS +.PP +The return value of the method has to be a list containing the names +of all subcommands supported by the \fIcmdPrefix\fR. This also tells +the Tcl core which version of the API for reflected channels is used by +this command handler. +.PP +Any error thrown by the method will abort the creation of the channel +and no channel will be created. The thrown error will appear as error +thrown by \fBchan create\fR. Any exception other than an \fBerror\fR +(e.g. \fBbreak\fR, etc.) is treated as (and converted to) an error. +.PP +\fBNote:\fR If the creation of the channel was aborted due to failures +here, then the \fBfinalize\fR subcommand will not be called. +.PP +The \fImode\fR argument tells the handler whether the channel was +opened for reading, writing, or both. It is a list containing any of +the strings \fBread\fR or \fBwrite\fR. The list will always +contain at least one element. +.PP +The subcommand must throw an error if the chosen mode is not +supported by the \fIcmdPrefix\fR. +.RE +.TP +\fIcmdPrefix \fBfinalize \fIchannelId\fR +. +An invocation of this subcommand will be the last call the +\fIcmdPrefix\fR will receive for the specified \fIchannelId\fR. It will +be generated just before the destruction of the data structures of the +channel held by the Tcl core. The command handler \fImust not\fR +access the \fIchannelId\fR anymore in no way. Upon this subcommand being +called, any internal resources allocated to this channel must be +cleaned up. +.RS +.PP +The return value of this subcommand is ignored. +.PP +If the subcommand throws an error the command which caused its +invocation (usually \fBclose\fR) will appear to have thrown this +error. Any exception beyond \fIerror\fR (e.g. \fIbreak\fR, etc.) is +treated as (and converted to) an error. +.PP +This subcommand is not invoked if the creation of the channel was +aborted during \fBinitialize\fR (See above). +.RE +.TP +\fIcmdPrefix \fBwatch \fIchannelId eventspec\fR +. +This subcommand notifies the \fIcmdPrefix\fR that the specified +\fIchannelId\fR is interested in the events listed in the +\fIeventspec\fR. This argument is a list containing any of \fBread\fR +and \fBwrite\fR. The list may be empty, which signals that the +channel does not wish to be notified of any events. In that situation, +the handler should disable event generation completely. +.RS +.PP +\fBWarning:\fR Any return value of the subcommand is ignored. This +includes all errors thrown by the subcommand, break, continue, and +custom return codes. +.PP +This subcommand interacts with \fBchan postevent\fR. Trying to post an +event which was not listed in the last call to \fBwatch\fR will cause +\fBchan postevent\fR to throw an error. +.RE +.SS "OPTIONAL SUBCOMMANDS" +.TP +\fIcmdPrefix \fBread \fIchannelId count\fR +. +This \fIoptional\fR subcommand is called when the user requests data from the +channel \fIchannelId\fR. \fIcount\fR specifies how many \fBbytes\fR have been +requested. If the subcommand is not supported then it is not possible to read +from the channel handled by the command. +.RS +.PP +The return value of this subcommand is taken as the requested data +\fIbytes\fR. If the returned data contains more bytes than requested, +an error will be signaled and later thrown by the command which +performed the read (usually \fBgets\fR or \fBread\fR). However, +returning fewer bytes than requested is acceptable. +.PP +Note that returning nothing (0 bytes) is a signal to the higher layers +that \fBEOF\fR has been reached on the channel. To signal that the +channel is out of data right now, but has not yet reached \fBEOF\fR, +it is necessary to throw the error "EAGAIN", i.e. to either +.PP +.CS +return -code error EAGAIN +.CE +or +.CS +error EAGAIN +.CE +.PP +For extensibility any error whose value is a negative integer number +will cause the higher layers to set the C-level variable "\fBerrno\fR" +to the absolute value of this number, signaling a system error. This +means that both +.PP +.CS +return -code error -11 +.CE +and +.CS +error -11 +.CE +.PP +are equivalent to the examples above, using the more readable string "EAGAIN". +No other error value has such a mapping to a symbolic string. +.PP +If the subcommand throws any other error, the command which caused its +invocation (usually \fBgets\fR, or \fBread\fR) will appear to have +thrown this error. Any exception beyond \fIerror\fR, (e.g. +\fIbreak\fR, etc.) is treated as and converted to an error. +.RE +.TP +\fIcmdPrefix \fBwrite \fIchannelId data\fR +. +This \fIoptional\fR subcommand is called when the user writes data to +the channel \fIchannelId\fR. The \fIdata\fR argument contains \fIbytes\fR, not +characters. Any type of transformation (EOL, encoding) configured for +the channel has already been applied at this point. If this subcommand +is not supported then it is not possible to write to the channel +handled by the command. +.RS +.PP +The return value of the subcommand is taken as the number of bytes +written by the channel. Anything non-numeric will cause an error to be +signaled and later thrown by the command which performed the write. A +negative value implies that the write failed. Returning a value +greater than the number of bytes given to the handler, or zero, is +forbidden and will cause the Tcl core to throw an error. +.PP +To signal that the channel is not able to accept data for writing +right now, it is necessary to throw the error "EAGAIN", i.e. to either +.PP +.CS +return -code error EAGAIN +.CE +or +.CS +error EAGAIN +.CE +.PP +For extensibility any error whose value is a negative integer number +will cause the higher layers to set the C-level variable "\fBerrno\fR" +to the absolute value of this number, signaling a system error. +However, note that the exact mapping between these error numbers and +their meanings is operating system dependent. +.PP +For example, while on Linux both +.PP +.CS +return -code error -11 +.CE +and +.CS +error -11 +.CE +.PP +are equivalent to the examples above, using the more readable string "EAGAIN", +this is not true for BSD, where the equivalent number is -35. +.PP +The symbolic string however is the same across systems, and internally +translated to the correct number. No other error value has such a mapping +to a symbolic string. +.PP +If the subcommand throws any other error the command which caused its +invocation (usually \fBputs\fR) will appear to have thrown this error. +Any exception beyond \fIerror\fR (e.g.\ \fIbreak\fR, etc.) is treated +as and converted to an error. +.RE +.TP +\fIcmdPrefix \fBseek \fIchannelId offset base\fR +. +This \fIoptional\fR subcommand is responsible for the handling of +\fBseek\fR and \fBtell\fR requests on the channel \fIchannelId\fR. If it is not +supported then seeking will not be possible for the channel. +.RS +.PP +The \fIbase\fR argument is one of +.TP 10 +\fBstart\fR +. +Seeking is relative to the beginning of the channel. +.TP 10 +\fBcurrent\fR +. +Seeking is relative to the current seek position. +.TP 10 +\fBend\fR +. +Seeking is relative to the end of the channel. +.PP +The \fIbase\fR argument of the builtin \fBchan seek\fR command takes +the same names. +.PP +The \fIoffset\fR is an integer number specifying the amount of +\fBbytes\fR to seek forward or backward. A positive number should seek +forward, and a negative number should seek backward. +.PP +A channel may provide only limited seeking. For example sockets can +seek forward, but not backward. +.PP +The return value of the subcommand is taken as the (new) location of +the channel, counted from the start. This has to be an integer number +greater than or equal to zero. +.PP +If the subcommand throws an error the command which caused its +invocation (usually \fBseek\fR, or \fBtell\fR) will appear to have +thrown this error. Any exception beyond \fIerror\fR (e.g. \fIbreak\fR, +etc.) is treated as and converted to an error. +.PP +The offset/base combination of 0/\fBcurrent\fR signals a \fBtell\fR +request, i.e. seek nothing relative to the current location, making +the new location identical to the current one, which is then returned. +.RE +.TP +\fIcmdPrefix \fBconfigure \fIchannelId option value\fR +. +This \fIoptional\fR subcommand is for setting the type-specific options of +channel \fIchannelId\fR. The \fIoption\fR argument indicates the option to be +written, and the \fIvalue\fR argument indicates the value to set the option to. +.RS +.PP +This subcommand will never try to update more than one option at a +time; that is behavior implemented in the Tcl channel core. +.PP +The return value of the subcommand is ignored. +.PP +If the subcommand throws an error the command which performed the +(re)configuration or query (usually \fBfconfigure\fR or \fBchan +configure\fR) will appear to have thrown this error. Any exception +beyond \fIerror\fR (e.g. \fIbreak\fR, etc.) is treated as and +converted to an error. +.RE +.TP +\fIcmdPrefix \fBcget \fIchannelId option\fR +. +This \fIoptional\fR subcommand is used when reading a single type-specific +option of channel \fIchannelId\fR. If this subcommand is supported then the +subcommand \fBcgetall\fR must be supported as well. +.RS +.PP +The subcommand should return the value of the specified \fIoption\fR. +.PP +If the subcommand throws an error, the command which performed the +(re)configuration or query (usually \fBfconfigure\fR) will appear to +have thrown this error. Any exception beyond \fIerror\fR (e.g. +\fIbreak\fR, etc.) is treated as and converted to an error. +.RE +.TP +\fIcmdPrefix \fBcgetall \fIchannelId\fR +. +This \fIoptional\fR subcommand is used for reading all type-specific options +of channel \fIchannelId\fR. If this subcommand is supported then the +subcommand \fBcget\fR has to be supported as well. +.RS +.PP +The subcommand should return a list of all options and their values. +This list must have an even number of elements. +.PP +If the subcommand throws an error the command which performed the +(re)configuration or query (usually \fBfconfigure\fR) will appear to +have thrown this error. Any exception beyond \fIerror\fR (e.g. +\fIbreak\fR, etc.) is treated as and converted to an error. +.RE +.TP +\fIcmdPrefix \fBblocking \fIchannelId mode\fR +. +This \fIoptional\fR subcommand handles changes to the blocking mode of the +channel \fIchannelId\fR. The \fImode\fR is a boolean flag. A true value means +that the channel has to be set to blocking, and a false value means that the +channel should be non-blocking. +.RS +.PP +The return value of the subcommand is ignored. +.PP +If the subcommand throws an error the command which caused its +invocation (usually \fBfconfigure\fR) will appear to have thrown this +error. Any exception beyond \fIerror\fR (e.g. \fIbreak\fR, etc.) is +treated as and converted to an error. +.RE +.SH NOTES +Some of the functions supported in channels defined in Tcl's C +interface are not available to channels reflected to the Tcl level. +.PP +The function \fBTcl_DriverGetHandleProc\fR is not supported; i.e. +reflected channels do not have OS specific handles. +.PP +The function \fBTcl_DriverHandlerProc\fR is not supported. This driver +function is relevant only for stacked channels, i.e. transformations. +Reflected channels are always base channels, not transformations. +.PP +The function \fBTcl_DriverFlushProc\fR is not supported. This is +because the current generic I/O layer of Tcl does not use this +function anywhere at all. Therefore support at the Tcl level makes no +sense either. This may be altered in the future (through extending the +API defined here and changing its version number) should the function +be used at some time in the future. +.SH "SEE ALSO" +chan(n) +.SH KEYWORDS +channel, reflection |