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Diffstat (limited to 'tcllib/idoc/man/files/modules/try/tcllib_try.n')
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diff --git a/tcllib/idoc/man/files/modules/try/tcllib_try.n b/tcllib/idoc/man/files/modules/try/tcllib_try.n new file mode 100644 index 0000000..304ea4d --- /dev/null +++ b/tcllib/idoc/man/files/modules/try/tcllib_try.n @@ -0,0 +1,397 @@ +'\" +'\" Generated from file 'tcllib_try\&.man' by tcllib/doctools with format 'nroff' +'\" Copyright (c) 2008 Donal K\&. Fellows, BSD licensed +'\" +.TH "try" n 1 tcllib "Forward compatibility implementation of [try]" +.\" 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 "" +.. +.BS +.SH NAME +try \- try - Trap and process errors and exceptions +.SH SYNOPSIS +package require \fBTcl 8\&.5\fR +.sp +package require \fBtry ?1?\fR +.sp +\fB::try\fR \fIbody\fR ?\fIhandler\&.\&.\&.\fR? ?\fBfinally\fR \fIscript\fR? +.sp +.BE +.SH DESCRIPTION +.PP +This package provides a forward-compatibility implementation of Tcl +8\&.6's try/finally command (TIP 329), for Tcl 8\&.5\&. The code was +directly pulled from Tcl 8\&.6 revision ?, when try/finally was +implemented as Tcl procedure instead of in C\&. +.TP +\fB::try\fR \fIbody\fR ?\fIhandler\&.\&.\&.\fR? ?\fBfinally\fR \fIscript\fR? +This command executes the script \fIbody\fR and, depending on what the +outcome of that script is (normal exit, error, or some other +exceptional result), runs a handler script to deal with the case\&. Once +that has all happened, if the \fBfinally\fR clause is present, the +\fIscript\fR it includes will be run and the result of the handler (or +the \fIbody\fR if no handler matched) is allowed to continue to +propagate\&. Note that the \fBfinally\fR clause is processed even if +an error occurs and irrespective of which, if any, \fIhandler\fR is +used\&. +.sp +The \fIhandler\fR clauses are each expressed as several words, +and must have one of the following forms: +.RS +.TP +\fBon\fR \fIcode variableList script\fR +This clause matches if the evaluation of \fIbody\fR completed with the +exception code \fIcode\fR\&. The \fIcode\fR may be expressed as an +integer or one of the following literal words: +\fBok\fR, \fBerror\fR, \fBreturn\fR, \fBbreak\fR, or +\fBcontinue\fR\&. Those literals correspond to the integers 0 through +4 respectively\&. +.TP +\fBtrap\fR \fIpattern variableList script\fR +This clause matches if the evaluation of \fIbody\fR resulted in an +error and the prefix of the \fB-errorcode\fR from the interpreter's +status dictionary is equal to the \fIpattern\fR\&. The number of prefix +words taken from the \fB-errorcode\fR is equal to the list-length +of \fIpattern\fR, and inter-word spaces are normalized in both the +\fB-errorcode\fR and \fIpattern\fR before comparison\&. +.sp +The \fIvariableList\fR word in each \fIhandler\fR is always +interpreted as a list of variable names\&. If the first word of the list +is present and non-empty, it names a variable into which the result of +the evaluation of \fIbody\fR (from the main \fBtry\fR) will be placed; +this will contain the human-readable form of any errors\&. If the second +word of the list is present and non-empty, it names a variable into +which the options dictionary of the interpreter at the moment of +completion of execution of \fIbody\fR will be placed\&. +.sp +The \fIscript\fR word of each \fIhandler\fR is also always +interpreted the same: as a Tcl script to evaluate if the clause is +matched\&. If \fIscript\fR is a literal \fB-\fR and the \fIhandler\fR +is not the last one, the \fIscript\fR of the following \fIhandler\fR +is invoked instead (just like with the \fBswitch\fR command)\&. +.sp +Note that \fIhandler\fR clauses are matched against in order, +and that the first matching one is always selected\&. +At most one \fIhandler\fR clause will selected\&. +As a consequence, an \fBon error\fR will mask any subsequent +\fBtrap\fR in the \fBtry\fR\&. Also note that \fBon error\fR is +equivalent to \fBtrap {}\fR\&. +.sp +If an exception (i\&.e\&. any non-\fBok\fR result) occurs during +the evaluation of either the \fIhandler\fR or the \fBfinally\fR +clause, the original exception's status dictionary will be added to +the new exception's status dictionary under the \fB-during\fR key\&. +.RE +.PP +.SH EXAMPLES +Ensure that a file is closed no matter what: +.PP +.CS + + +set f [open /some/file/name a] +\fBtry\fR { + puts \\$f "some message" + # \&.\&.\&. +} \fBfinally\fR { + close \\$f +} + +.CE +.PP +Handle different reasons for a file to not be openable for reading: +.PP +.CS + + +\fBtry\fR { + set f [open /some/file/name] +} \fBtrap\fR {POSIX EISDIR} {} { + puts "failed to open /some/file/name: it's a directory" +} \fBtrap\fR {POSIX ENOENT} {} { + puts "failed to open /some/file/name: it doesn't exist" +} + +.CE +.SH "BUGS, IDEAS, FEEDBACK" +This document, and the package it describes, will undoubtedly contain +bugs and other problems\&. +Please report such in the category \fItry\fR of the +\fITcllib Trackers\fR [http://core\&.tcl\&.tk/tcllib/reportlist]\&. +Please also report any ideas for enhancements you may have for either +package and/or documentation\&. +.SH "SEE ALSO" +catch(n), error(n), return(n), throw(n) +.SH KEYWORDS +cleanup, error, exception, final, resource management +.SH CATEGORY +Utility +.SH COPYRIGHT +.nf +Copyright (c) 2008 Donal K\&. Fellows, BSD licensed + +.fi
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