'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
-'\" RCS: @(#) $Id: Async.3,v 1.5 2000/07/26 01:29:00 davidg Exp $
-'\"
-'\" The 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.
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-'\" End of vertical sidebar.
-'\"
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-'\" Begin an indented unfilled display.
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-'\"
-'\" .SE
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-'\" Print arg1 underlined, then print arg2 normally.
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-'\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $
-'\"
-'\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
+.TH Tcl_AsyncCreate 3 7.0 Tcl "Tcl Library Procedures"
+.\" 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.
+.\"
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+.\" 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.
+.\"
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+.\" 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
+.\" # Start an argument description
.de AP
.ie !"\\$4"" .TP \\$4
.el \{\
.\}
.ta \\n()Au \\n()Bu
.ie !"\\$3"" \{\
-\&\\$1 \\fI\\$2\\fP (\\$3)
+\&\\$1 \\fI\\$2\\fP (\\$3)
.\".b
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.el \{\
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..
-'\" # define tabbing values for .AP
+.\" # define tabbing values for .AP
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.nr )A 10n
.if !"\\$1"" .nr )A \\w'\\$1'u+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
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+.\" # BS - start boxed text
+.\" # ^y = starting y location
+.\" # ^b = 1
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.if n \l'\\n(.lu\(ul'
.if n .fi
..
-'\" # BE - end boxed text (draw box now)
+.\" # BE - end boxed text (draw box now)
.de BE
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.nr ^b 0
..
-'\" # VS - start vertical sidebar
-'\" # ^Y = starting y location
-'\" # ^v = 1 (for troff; for nroff this doesn't matter)
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+.\" # ^Y = starting y location
+.\" # ^v = 1 (for troff; for nroff this doesn't matter)
.de VS
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.ie n 'mc \s12\(br\s0
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..
-'\" # VE - end of vertical sidebar
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.de VE
.ie n 'mc
.el \{\
.\}
.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.
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+.\" # box/sidebar if in box/sidebar mode, then invoked standard
+.\" # page bottom macro.
.de ^B
.ev 2
'ti 0
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..
-'\" # DS - begin display
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.de DS
.RS
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.sp
..
-'\" # DE - end display
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.fi
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.sp
..
-'\" # SO - start of list of standard options
+.\" # SO - start of list of standard options
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+'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
+.\" # SE - end of list of standard options
.de SE
.fi
.ft R
.LP
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+See the \\*(So manual entry for details on the standard options.
..
-'\" # OP - start of full description for a single option
+.\" # OP - start of full description for a single option
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..
-'\" # CS - begin code excerpt
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.ta .25i .5i .75i 1i
..
-'\" # CE - end code excerpt
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..
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.de UL
\\$1\l'|0\(ul'\\$2
..
-.TH Tcl_AsyncCreate 3 7.0 Tcl "Tcl Library Procedures"
+.\" # 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
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+.\"" 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
Tcl_AsyncCreate, Tcl_AsyncMark, Tcl_AsyncInvoke, Tcl_AsyncDelete, Tcl_AsyncReady \- handle asynchronous events
These procedures provide a safe mechanism for dealing with
asynchronous events such as signals.
If an event such as a signal occurs while a Tcl script is being
-evaluated then it isn't safe to take any substantive action to
+evaluated then it is not safe to take any substantive action to
process the event.
-For example, it isn't safe to evaluate a Tcl script since the
+For example, it is not safe to evaluate a Tcl script since the
interpreter may already be in the middle of evaluating a script;
it may not even be safe to allocate memory, since a memory
allocation could have been in progress when the event occurred.
.PP
\fBTcl_AsyncCreate\fR, \fBTcl_AsyncDelete\fR, and \fBTcl_AsyncReady\fR
are thread sensitive. They access and/or set a thread-specific data
-structure in the event of an --enable-thread built core. The token
-created by Tcl_AsyncCreate contains the needed thread information it
-was called from so that calling Tcl_AsyncMark(token) will only yield
-the origin thread into the AsyncProc.
-.PP
+structure in the event of a core built with \fI\-\-enable\-threads\fR. The token
+created by \fBTcl_AsyncCreate\fR contains the needed thread information it
+was called from so that calling \fBTcl_AsyncMark\fR(\fItoken\fR) will only yield
+the origin thread into the asynchronous handler.
+.PP
\fBTcl_AsyncCreate\fR creates an asynchronous handler and returns
a token for it.
The asynchronous handler must be created before
the actions associated with the asynchronous event.
\fIProc\fR should have arguments and result that match the
type \fBTcl_AsyncProc\fR:
+.PP
.CS
-typedef int Tcl_AsyncProc(
- ClientData \fIclientData\fR,
- Tcl_Interp *\fIinterp\fR,
- int \fIcode\fR);
+typedef int \fBTcl_AsyncProc\fR(
+ ClientData \fIclientData\fR,
+ Tcl_Interp *\fIinterp\fR,
+ int \fIcode\fR);
.CE
+.PP
The \fIclientData\fR will be the same as the \fIclientData\fR
argument passed to \fBTcl_AsyncCreate\fR when the handler was
created.
\fBTcl_AsyncInvoke\fR will invoke them all; at each point it
invokes the highest-priority (oldest) ready handler, repeating
this over and over until there are no longer any ready handlers.
-
.SH WARNING
.PP
It is almost always a bad idea for an asynchronous event
subtle ways and result in bugs that are extremely difficult
to track down.
If an asynchronous event handler needs to evaluate Tcl scripts
-then it should first save the interpreter's result plus the values
-of the variables \fBerrorInfo\fR and \fBerrorCode\fR (this can
-be done, for example, by storing them in dynamic strings).
+then it should first save the interpreter's state by calling
+\fBTcl_SaveInterpState\fR, passing in the \fIcode\fR argument.
When the asynchronous handler is finished it should restore
-the interpreter's result, \fBerrorInfo\fR, and \fBerrorCode\fR,
-and return the \fIcode\fR argument.
+the interpreter's state by calling \fBTcl_RestoreInterpState\fR,
+and then returning the \fIcode\fR argument.
.SH KEYWORDS
-asynchronous event, handler, signal
+asynchronous event, handler, signal, Tcl_SaveInterpState, thread
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