[OpenSPARC-T2-SAM] / sam-t2 / devtools / v8plus / man / mann / uplevel.n

'\"
'\" Copyright (c) 1993 The Regents of the University of California.
'\" Copyright (c) 1994-1997 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" RCS: @(#) $Id: uplevel.n,v 1.3.18.1 2004/10/27 14:43:15 dkf 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.
'\"	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.
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'\" .SO
'\"	Start of list of standard options for a Tk widget.  The
'\"	options follow on successive lines, in four 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.
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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.
.if t .wh -1.3i ^B
.nr ^l \n(.l
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.de AP
.ie !"\\$4"" .TP \\$4
.el \{\
.   ie !"\\$2"" .TP \\n()Cu
.   el          .TP 15
.\}
.ta \\n()Au \\n()Bu
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\&\\$1	\\fI\\$2\\fP	(\\$3)
.\".b
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.br
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\&\\$1	\\fI\\$2\\fP
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..
.AS Tcl_Interp Tcl_CreateInterp in/out
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.\}
.el \}\
\h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
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.\"	draw two sides but no top otherwise.
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.el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.\}
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\kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c
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.SH "STANDARD OPTIONS"
.LP
.nf
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..
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.ft R
.LP
See the \\fBoptions\\fR 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
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\\$1\l'|0\(ul'\\$2
..
.TH uplevel n "" Tcl "Tcl Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
uplevel \- Execute a script in a different stack frame
.SH SYNOPSIS
\fBuplevel \fR?\fIlevel\fR?\fI arg \fR?\fIarg ...\fR?
.BE

.SH DESCRIPTION
.PP
All of the \fIarg\fR arguments are concatenated as if they had
been passed to \fBconcat\fR; the result is then evaluated in the
variable context indicated by \fIlevel\fR.  \fBUplevel\fR returns
the result of that evaluation.
.PP
If \fIlevel\fR is an integer then
it gives a distance (up the procedure calling stack) to move before
executing the command.  If \fIlevel\fR consists of \fB#\fR followed by
a number then the number gives an absolute level number.  If \fIlevel\fR
is omitted then it defaults to \fB1\fR.  \fILevel\fR cannot be
defaulted if the first \fIcommand\fR argument starts with a digit or \fB#\fR.
.PP
For example, suppose that procedure \fBa\fR was invoked
from top-level, and that it called \fBb\fR, and that \fBb\fR called \fBc\fR.
Suppose that \fBc\fR invokes the \fBuplevel\fR command.  If \fIlevel\fR
is \fB1\fR or \fB#2\fR  or omitted, then the command will be executed
in the variable context of \fBb\fR.  If \fIlevel\fR is \fB2\fR or \fB#1\fR
then the command will be executed in the variable context of \fBa\fR.
If \fIlevel\fR is \fB3\fR or \fB#0\fR then the command will be executed
at top-level (only global variables will be visible).
.PP
The \fBuplevel\fR command causes the invoking procedure to disappear
from the procedure calling stack while the command is being executed.
In the above example, suppose \fBc\fR invokes the command
.CS
\fBuplevel\fR 1 {set x 43; d}
.CE
where \fBd\fR is another Tcl procedure.  The \fBset\fR command will
modify the variable \fBx\fR in \fBb\fR's context, and \fBd\fR will execute
at level 3, as if called from \fBb\fR.  If it in turn executes
the command
.CS
\fBuplevel\fR {set x 42}
.CE
then the \fBset\fR command will modify the same variable \fBx\fR in \fBb\fR's
context:  the procedure \fBc\fR does not appear to be on the call stack
when \fBd\fR is executing.  The command ``\fBinfo level\fR'' may
be used to obtain the level of the current procedure.
.PP
\fBUplevel\fR makes it possible to implement new control
constructs as Tcl procedures (for example, \fBuplevel\fR could
be used to implement the \fBwhile\fR construct as a Tcl procedure).
.PP
\fBnamespace eval\fR is another way (besides procedure calls)
that the Tcl naming context can change.
It adds a call frame to the stack to represent the namespace context.
This means each \fBnamespace eval\fR command
counts as another call level for \fBuplevel\fR and \fBupvar\fR commands.
For example, \fBinfo level 1\fR will return a list
describing a command that is either
the outermost procedure call or the outermost \fBnamespace eval\fR command.
Also, \fBuplevel #0\fR evaluates a script
at top-level in the outermost namespace (the global namespace).
.SH EXAMPLE
As stated above, the \fBuplevel\fR command is useful for creating new
control constructs.  This example shows how (without error handling)
it can be used to create a \fBdo\fR command that is the counterpart of
\fBwhile\fR except for always performing the test after running the
loop body:
.CS
proc do {body while condition} {
    if {$while ne "while"} {
        error "required word missing"
    }
    set conditionCmd [list expr $condition]
    while {1} {
        \fBuplevel\fR 1 $body
        if {![\fBuplevel\fR 1 $conditionCmd]} {
            break
        }
    }
}
.CE

.SH "SEE ALSO"
namespace(n), upvar(n)

.SH KEYWORDS
context, level, namespace, stack frame, variables
Commit	Line	Data
920dae64 AT	1	'\"
	2	'\" Copyright (c) 1993 The Regents of the University of California.
	3	'\" Copyright (c) 1994-1997 Sun Microsystems, Inc.
	4	'\"
	5	'\" See the file "license.terms" for information on usage and redistribution
	6	'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
	7	'\"
	8	'\" RCS: @(#) $Id: uplevel.n,v 1.3.18.1 2004/10/27 14:43:15 dkf Exp $
	9	'\"
	10	'\" The definitions below are for supplemental macros used in Tcl/Tk
	11	'\" manual entries.
	12	'\"
	13	'\" .AP type name in/out ?indent?
	14	'\" Start paragraph describing an argument to a library procedure.
	15	'\" type is type of argument (int, etc.), in/out is either "in", "out",
	16	'\" or "in/out" to describe whether procedure reads or modifies arg,
	17	'\" and indent is equivalent to second arg of .IP (shouldn't ever be
	18	'\" needed; use .AS below instead)
	19	'\"
	20	'\" .AS ?type? ?name?
	21	'\" Give maximum sizes of arguments for setting tab stops. Type and
	22	'\" name are examples of largest possible arguments that will be passed
	23	'\" to .AP later. If args are omitted, default tab stops are used.
	24	'\"
	25	'\" .BS
	26	'\" Start box enclosure. From here until next .BE, everything will be
	27	'\" enclosed in one large box.
	28	'\"
	29	'\" .BE
	30	'\" End of box enclosure.
	31	'\"
	32	'\" .CS
	33	'\" Begin code excerpt.
	34	'\"
	35	'\" .CE
	36	'\" End code excerpt.
	37	'\"
	38	'\" .VS ?version? ?br?
	39	'\" Begin vertical sidebar, for use in marking newly-changed parts
	40	'\" of man pages. The first argument is ignored and used for recording
	41	'\" the version when the .VS was added, so that the sidebars can be
	42	'\" found and removed when they reach a certain age. If another argument
	43	'\" is present, then a line break is forced before starting the sidebar.
	44	'\"
	45	'\" .VE
	46	'\" End of vertical sidebar.
	47	'\"
	48	'\" .DS
	49	'\" Begin an indented unfilled display.
	50	'\"
	51	'\" .DE
	52	'\" End of indented unfilled display.
	53	'\"
	54	'\" .SO
	55	'\" Start of list of standard options for a Tk widget. The
	56	'\" options follow on successive lines, in four columns separated
	57	'\" by tabs.
	58	'\"
	59	'\" .SE
	60	'\" End of list of standard options for a Tk widget.
	61	'\"
	62	'\" .OP cmdName dbName dbClass
	63	'\" Start of description of a specific option. cmdName gives the
	64	'\" option's name as specified in the class command, dbName gives
65	'\" the option's name in the option database, and dbClass gives
66	'\" the option's class in the option database.
67	'\"
68	'\" .UL arg1 arg2
69	'\" Print arg1 underlined, then print arg2 normally.
70	'\"
71	'\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $
72	'\"
73	'\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
74	.if t .wh -1.3i ^B
75	.nr ^l \n(.l
76	.ad b
77	'\" # Start an argument description
78	.de AP
79	.ie !"\\$4"" .TP \\$4
80	.el \{\
81	. ie !"\\$2"" .TP \\n()Cu
82	. el .TP 15
83	.\}
84	.ta \\n()Au \\n()Bu
85	.ie !"\\$3"" \{\
86	\&\\$1 \\fI\\$2\\fP (\\$3)
87	.\".b
88	.\}
89	.el \{\
90	.br
91	.ie !"\\$2"" \{\
92	\&\\$1 \\fI\\$2\\fP
93	.\}
94	.el \{\
95	\&\\fI\\$1\\fP
96	.\}
97	.\}
98	..
99	'\" # define tabbing values for .AP
100	.de AS
101	.nr )A 10n
102	.if !"\\$1"" .nr )A \\w'\\$1'u+3n
103	.nr )B \\n()Au+15n
104	.\"
105	.if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
106	.nr )C \\n()Bu+\\w'(in/out)'u+2n
107	..
108	.AS Tcl_Interp Tcl_CreateInterp in/out
109	'\" # BS - start boxed text
110	'\" # ^y = starting y location
111	'\" # ^b = 1
112	.de BS
113	.br
114	.mk ^y
115	.nr ^b 1u
116	.if n .nf
117	.if n .ti 0
118	.if n \l'\\n(.lu\(ul'
119	.if n .fi
120	..
121	'\" # BE - end boxed text (draw box now)
122	.de BE
123	.nf
124	.ti 0
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126	.ie n \l'\\n(^lu\(ul'
127	.el \{\
128	.\" Draw four-sided box normally, but don't draw top of
129	.\" box if the box started on an earlier page.
130	.ie !\\n(^b-1 \{\
131	\h'-1.5n'\L'\|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'\|0u-1.5n\(ul'
132	.\}
133	.el \}\
134	\h'-1.5n'\L'\|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'\|0u-1.5n\(ul'
135	.\}
136	.\}
137	.fi
138	.br
139	.nr ^b 0
140	..
141	'\" # VS - start vertical sidebar
142	'\" # ^Y = starting y location
143	'\" # ^v = 1 (for troff; for nroff this doesn't matter)
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148	.el .nr ^v 1u
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151	.de VE
152	.ie n 'mc
153	.el \{\
154	.ev 2
155	.nf
156	.ti 0
157	.mk ^t
158	\h'\|\\n(^lu+3n'\L'\|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-\|\\n(^lu+3n'
159	.sp -1
160	.fi
161	.ev
162	.\}
163	.nr ^v 0
164	..
165	'\" # Special macro to handle page bottom: finish off current
166	'\" # box/sidebar if in box/sidebar mode, then invoked standard
167	'\" # page bottom macro.
168	.de ^B
169	.ev 2
170	'ti 0
171	'nf
172	.mk ^t
173	.if \\n(^b \{\
174	.\" Draw three-sided box if this is the box's first page,
175	.\" draw two sides but no top otherwise.
176	.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
177	.el \h'-1.5n'\L'\|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'\|0u'\c
178	.\}
179	.if \\n(^v \{\
180	.nr ^x \\n(^tu+1v-\\n(^Yu
181	\kx\h'-\\nxu'\h'\|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'\|0u'\c
182	.\}
183	.bp
184	'fi
185	.ev
186	.if \\n(^b \{\
187	.mk ^y
188	.nr ^b 2
189	.\}
190	.if \\n(^v \{\
191	.mk ^Y
192	.\}
193	..
194	'\" # DS - begin display
195	.de DS
196	.RS
197	.nf
198	.sp
199	..
200	'\" # DE - end display
201	.de DE
202	.fi
203	.RE
204	.sp
205	..
206	'\" # SO - start of list of standard options
207	.de SO
208	.SH "STANDARD OPTIONS"
209	.LP
210	.nf
211	.ta 5.5c 11c
212	.ft B
213	..
214	'\" # SE - end of list of standard options
215	.de SE
216	.fi
217	.ft R
218	.LP
219	See the \\fBoptions\\fR manual entry for details on the standard options.
220	..
221	'\" # OP - start of full description for a single option
222	.de OP
223	.LP
224	.nf
225	.ta 4c
226	Command-Line Name: \\fB\\$1\\fR
227	Database Name: \\fB\\$2\\fR
228	Database Class: \\fB\\$3\\fR
229	.fi
230	.IP
231	..
232	'\" # CS - begin code excerpt
233	.de CS
234	.RS
235	.nf
236	.ta .25i .5i .75i 1i
237	..
238	'\" # CE - end code excerpt
239	.de CE
240	.fi
241	.RE
242	..
243	.de UL
244	\\$1\l'\|0\(ul'\\$2
245	..
246	.TH uplevel n "" Tcl "Tcl Built-In Commands"
247	.BS
248	'\" Note: do not modify the .SH NAME line immediately below!
249	.SH NAME
250	uplevel \- Execute a script in a different stack frame
251	.SH SYNOPSIS
252	\fBuplevel \fR?\fIlevel\fR?\fI arg \fR?\fIarg ...\fR?
253	.BE
254
255	.SH DESCRIPTION
256	.PP
257	All of the \fIarg\fR arguments are concatenated as if they had
258	been passed to \fBconcat\fR; the result is then evaluated in the
259	variable context indicated by \fIlevel\fR. \fBUplevel\fR returns
260	the result of that evaluation.
261	.PP
262	If \fIlevel\fR is an integer then
263	it gives a distance (up the procedure calling stack) to move before
264	executing the command. If \fIlevel\fR consists of \fB#\fR followed by
265	a number then the number gives an absolute level number. If \fIlevel\fR
266	is omitted then it defaults to \fB1\fR. \fILevel\fR cannot be
267	defaulted if the first \fIcommand\fR argument starts with a digit or \fB#\fR.
268	.PP
269	For example, suppose that procedure \fBa\fR was invoked
270	from top-level, and that it called \fBb\fR, and that \fBb\fR called \fBc\fR.
271	Suppose that \fBc\fR invokes the \fBuplevel\fR command. If \fIlevel\fR
272	is \fB1\fR or \fB#2\fR or omitted, then the command will be executed
273	in the variable context of \fBb\fR. If \fIlevel\fR is \fB2\fR or \fB#1\fR
274	then the command will be executed in the variable context of \fBa\fR.
275	If \fIlevel\fR is \fB3\fR or \fB#0\fR then the command will be executed
276	at top-level (only global variables will be visible).
277	.PP
278	The \fBuplevel\fR command causes the invoking procedure to disappear
279	from the procedure calling stack while the command is being executed.
280	In the above example, suppose \fBc\fR invokes the command
281	.CS
282	\fBuplevel\fR 1 {set x 43; d}
283	.CE
284	where \fBd\fR is another Tcl procedure. The \fBset\fR command will
285	modify the variable \fBx\fR in \fBb\fR's context, and \fBd\fR will execute
286	at level 3, as if called from \fBb\fR. If it in turn executes
287	the command
288	.CS
289	\fBuplevel\fR {set x 42}
290	.CE
291	then the \fBset\fR command will modify the same variable \fBx\fR in \fBb\fR's
292	context: the procedure \fBc\fR does not appear to be on the call stack
293	when \fBd\fR is executing. The command ``\fBinfo level\fR'' may
294	be used to obtain the level of the current procedure.
295	.PP
296	\fBUplevel\fR makes it possible to implement new control
297	constructs as Tcl procedures (for example, \fBuplevel\fR could
298	be used to implement the \fBwhile\fR construct as a Tcl procedure).
299	.PP
300	\fBnamespace eval\fR is another way (besides procedure calls)
301	that the Tcl naming context can change.
302	It adds a call frame to the stack to represent the namespace context.
303	This means each \fBnamespace eval\fR command
304	counts as another call level for \fBuplevel\fR and \fBupvar\fR commands.
305	For example, \fBinfo level 1\fR will return a list
306	describing a command that is either
307	the outermost procedure call or the outermost \fBnamespace eval\fR command.
308	Also, \fBuplevel #0\fR evaluates a script
309	at top-level in the outermost namespace (the global namespace).
310	.SH EXAMPLE
311	As stated above, the \fBuplevel\fR command is useful for creating new
312	control constructs. This example shows how (without error handling)
313	it can be used to create a \fBdo\fR command that is the counterpart of
314	\fBwhile\fR except for always performing the test after running the
315	loop body:
316	.CS
317	proc do {body while condition} {
318	if {$while ne "while"} {
319	error "required word missing"
320	}
321	set conditionCmd [list expr $condition]
322	while {1} {
323	\fBuplevel\fR 1 $body
324	if {![\fBuplevel\fR 1 $conditionCmd]} {
325	break
326	}
327	}
328	}
329	.CE
330
331	.SH "SEE ALSO"
332	namespace(n), upvar(n)
333
334	.SH KEYWORDS
335	context, level, namespace, stack frame, variables