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Diffstat (limited to 'doc/interp.n')
| -rw-r--r-- | doc/interp.n | 525 |
1 files changed, 340 insertions, 185 deletions
diff --git a/doc/interp.n b/doc/interp.n index 8516941..92113a6 100644 --- a/doc/interp.n +++ b/doc/interp.n @@ -1,28 +1,26 @@ '\" '\" Copyright (c) 1995-1996 Sun Microsystems, Inc. '\" Copyright (c) 2004 Donal K. Fellows +'\" Copyright (c) 2006-2008 Joe Mistachkin. '\" '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. '\" -'\" RCS: @(#) $Id: interp.n,v 1.19 2004/10/27 14:24:37 dkf Exp $ -'\" +.TH interp n 8.6 Tcl "Tcl Built-In Commands" .so man.macros -.TH interp n 7.6 Tcl "Tcl Built-In Commands" .BS '\" Note: do not modify the .SH NAME line immediately below! .SH NAME interp \- Create and manipulate Tcl interpreters .SH SYNOPSIS -\fBinterp \fIoption \fR?\fIarg arg ...\fR? +\fBinterp \fIsubcommand \fR?\fIarg arg ...\fR? .BE - .SH DESCRIPTION .PP -This command makes it possible to create one or more new Tcl +This command makes it possible to create one or more new Tcl interpreters that co-exist with the creating interpreter in the same application. The creating interpreter is called the \fImaster\fR -and the new interpreter is called a \fIslave\fR. +and the new interpreter is called a \fIslave\fR. A master can create any number of slaves, and each slave can itself create additional slaves for which it is master, resulting in a hierarchy of interpreters. @@ -36,10 +34,7 @@ command to be invoked in its master interpreter or in another slave interpreter. The only other connections between interpreters are through environment variables (the \fBenv\fR variable), which are normally shared among all interpreters in the application, -.VS 8.5 -and by resource limit exceeded callbacks. -.VE -Note that the +and by resource limit exceeded callbacks. Note that the name space for files (such as the names returned by the \fBopen\fR command) is no longer shared between interpreters. Explicit commands are provided to share files and to transfer references to open files from one interpreter @@ -59,17 +54,25 @@ instead, it is \fIhidden\fR, so that only trusted interpreters can obtain access to it. For a detailed explanation of hidden commands, see \fBHIDDEN COMMANDS\fR, below. The alias mechanism can be used for protected communication (analogous to a -kernel call) between a slave interpreter and its master. -See \fBALIAS INVOCATION\fR, below, for more details +kernel call) between a slave interpreter and its master. +See \fBALIAS INVOCATION\fR, below, for more details on how the alias mechanism works. .PP A qualified interpreter name is a proper Tcl lists containing a subset of its ancestors in the interpreter hierarchy, terminated by the string naming the interpreter in its immediate master. Interpreter names are relative to the -interpreter in which they are used. For example, if \fBa\fR is a slave of -the current interpreter and it has a slave \fBa1\fR, which in turn has a -slave \fBa11\fR, the qualified name of \fBa11\fR in \fBa\fR is the list -\fBa1 a11\fR. +interpreter in which they are used. For example, if +.QW \fBa\fR +is a slave of the current interpreter and it has a slave +.QW \fBa1\fR , +which in turn has a slave +.QW \fBa11\fR , +the qualified name of +.QW \fBa11\fR +in +.QW \fBa\fR +is the list +.QW "\fBa1 a11\fR" . .PP The \fBinterp\fR command, described below, accepts qualified interpreter names as arguments; the interpreter in which the command is being evaluated @@ -83,9 +86,10 @@ Both restrictions are motivated by safety concerns. The \fBinterp\fR command is used to create, delete, and manipulate slave interpreters, and to share or transfer channels between interpreters. It can have any of several forms, depending -on the \fIoption\fR argument: +on the \fIsubcommand\fR argument: .TP \fBinterp\fR \fBalias\fR \fIsrcPath\fR \fIsrcToken\fR +. Returns a Tcl list whose elements are the \fItargetCmd\fR and \fIarg\fRs associated with the alias represented by \fIsrcToken\fR (this is the value returned when the alias was @@ -93,6 +97,7 @@ created; it is possible that the name of the source command in the slave is different from \fIsrcToken\fR). .TP \fBinterp\fR \fBalias\fR \fIsrcPath\fR \fIsrcToken\fR \fB{}\fR +. Deletes the alias for \fIsrcToken\fR in the slave interpreter identified by \fIsrcPath\fR. \fIsrcToken\fR refers to the value returned when the alias @@ -100,6 +105,7 @@ was created; if the source command has been renamed, the renamed command will be deleted. .TP \fBinterp\fR \fBalias\fR \fIsrcPath\fR \fIsrcCmd\fR \fItargetPath\fR \fItargetCmd \fR?\fIarg arg ...\fR? +. This command creates an alias between one slave and another (see the \fBalias\fR slave command below for creating aliases between a slave and its master). In this command, either of the slave interpreters @@ -107,11 +113,15 @@ may be anywhere in the hierarchy of interpreters under the interpreter invoking the command. \fISrcPath\fR and \fIsrcCmd\fR identify the source of the alias. \fISrcPath\fR is a Tcl list whose elements select a particular -interpreter. For example, ``\fBa b\fR'' identifies an interpreter -\fBb\fR, which is a slave of interpreter \fBa\fR, which is a slave -of the invoking interpreter. An empty list specifies the interpreter -invoking the command. \fIsrcCmd\fR gives the name of a new -command, which will be created in the source interpreter. +interpreter. For example, +.QW "\fBa b\fR" +identifies an interpreter +.QW \fBb\fR , +which is a slave of interpreter +.QW \fBa\fR , +which is a slave of the invoking interpreter. An empty list specifies +the interpreter invoking the command. \fIsrcCmd\fR gives the name of +a new command, which will be created in the source interpreter. \fITargetPath\fR and \fItargetCmd\fR specify a target interpreter and command, and the \fIarg\fR arguments, if any, specify additional arguments to \fItargetCmd\fR which are prepended to any arguments specified @@ -121,24 +131,51 @@ already exist; it is not created by this command. The alias arranges for the given target command to be invoked in the target interpreter whenever the given source command is invoked in the source interpreter. See \fBALIAS INVOCATION\fR below for -more details. +more details. The command returns a token that uniquely identifies the command created \fIsrcCmd\fR, even if the command is renamed afterwards. The token may but does not have to be equal to \fIsrcCmd\fR. .TP \fBinterp\fR \fBaliases \fR?\fIpath\fR? +. This command returns a Tcl list of the tokens of all the source commands for aliases defined in the interpreter identified by \fIpath\fR. The tokens -correspond to the values returned when -the aliases were created (which may not be the same +correspond to the values returned when +the aliases were created (which may not be the same as the current names of the commands). .TP +\fBinterp bgerror \fIpath\fR ?\fIcmdPrefix\fR? +. +This command either gets or sets the current background exception handler +for the interpreter identified by \fIpath\fR. If \fIcmdPrefix\fR is +absent, the current background exception handler is returned, and if it is +present, it is a list of words (of minimum length one) that describes +what to set the interpreter's background exception handler to. See the +\fBBACKGROUND EXCEPTION HANDLING\fR section for more details. +.TP +\fBinterp\fR \fBcancel \fR?\fB\-unwind\fR? ?\fB\-\|\-\fR? ?\fIpath\fR? ?\fIresult\fR? +.VS 8.6 +Cancels the script being evaluated in the interpreter identified by +\fIpath\fR. Without the \fB\-unwind\fR switch the evaluation stack for +the interpreter is unwound until an enclosing catch command is found or +there are no further invocations of the interpreter left on the call +stack. With the \fB\-unwind\fR switch the evaluation stack for the +interpreter is unwound without regard to any intervening catch command +until there are no further invocations of the interpreter left on the +call stack. The \fB\-\|\-\fR switch can be used to mark the end of +switches; it may be needed if \fIpath\fR is an unusual value such +as \fB\-safe\fR. If \fIresult\fR is present, it will be used as the +error message string; otherwise, a default error message string will be +used. +.VE 8.6 +.TP \fBinterp\fR \fBcreate \fR?\fB\-safe\fR? ?\fB\-\|\-\fR? ?\fIpath\fR? +. Creates a slave interpreter identified by \fIpath\fR and a new command, called a \fIslave command\fR. The name of the slave command is the last component of \fIpath\fR. The new slave interpreter and the slave command are created in the interpreter identified by the path obtained by removing -the last component from \fIpath\fR. For example, if \fIpath is \fBa b +the last component from \fIpath\fR. For example, if \fIpath\fR is \fBa b c\fR then a new slave interpreter and slave command named \fBc\fR are created in the interpreter identified by the path \fBa b\fR. The slave command may be used to manipulate the new interpreter as @@ -157,7 +194,50 @@ given name already exists in this master. The initial recursion limit of the slave interpreter is set to the current recursion limit of its parent interpreter. .TP +\fBinterp\fR \fBdebug \fIpath\fR ?\fB\-frame\fR ?\fIbool\fR?? +. +Controls whether frame-level stack information is captured in the +slave interpreter identified by \fIpath\fR. If no arguments are +given, option and current setting are returned. If \fB\-frame\fR +is given, the debug setting is set to the given boolean if provided +and the current setting is returned. +This only effects the output of \fBinfo frame\fR, in that exact +frame-level information for command invocation at the bytecode level +is only captured with this setting on. +.RS +.PP +For example, with code like +.PP +.CS +\fBproc\fR mycontrol {... script} { + ... + \fBuplevel\fR 1 $script + ... +} + +\fBproc\fR dosomething {...} { + ... + mycontrol { + somecode + } +} +.CE +.PP +the standard setting will provide a relative line number for the +command \fBsomecode\fR and the relevant frame will be of type +\fBeval\fR. With frame-debug active on the other hand the tracking +extends so far that the system will be able to determine the file and +absolute line number of this command, and return a frame of type +\fBsource\fR. This more exact information is paid for with slower +execution of all commands. +.PP +Note that once it is on, this flag cannot be switched back off: such +attempts are silently ignored. This is needed to maintain the +consistency of the underlying interpreter's state. +.RE +.TP \fBinterp\fR \fBdelete \fR?\fIpath ...?\fR +. Deletes zero or more interpreters given by the optional \fIpath\fR arguments, and for each interpreter, it also deletes its slaves. The command also deletes the slave command for each interpreter deleted. @@ -165,12 +245,13 @@ For each \fIpath\fR argument, if no interpreter by that name exists, the command raises an error. .TP \fBinterp\fR \fBeval\fR \fIpath arg \fR?\fIarg ...\fR? +. This command concatenates all of the \fIarg\fR arguments in the same fashion as the \fBconcat\fR command, then evaluates the resulting string as a Tcl script in the slave interpreter identified by \fIpath\fR. The result -of this evaluation (including error information such as the \fBerrorInfo\fR -and \fBerrorCode\fR variables, if an error occurs) is returned to the -invoking interpreter. +of this evaluation (including all \fBreturn\fR options, +such as \fB\-errorinfo\fR and \fB\-errorcode\fR information, if an +error occurs) is returned to the invoking interpreter. Note that the script will be executed in the current context stack frame of the \fIpath\fR interpreter; this is so that the implementations (in a master interpreter) of aliases in a slave interpreter can execute scripts in @@ -178,11 +259,13 @@ the slave that find out information about the slave's current state and stack frame. .TP \fBinterp exists \fIpath\fR -Returns \fB1\fR if a slave interpreter by the specified \fIpath\fR +. +Returns \fB1\fR if a slave interpreter by the specified \fIpath\fR exists in this master, \fB0\fR otherwise. If \fIpath\fR is omitted, the invoking interpreter is used. .TP \fBinterp expose \fIpath\fR \fIhiddenName\fR ?\fIexposedCmdName\fR? +. Makes the hidden command \fIhiddenName\fR exposed, eventually bringing it back under a new \fIexposedCmdName\fR name (this name is currently accepted only if it is a valid global name space name without any ::), @@ -193,13 +276,14 @@ fails. Hidden commands are explained in more detail in \fBHIDDEN COMMANDS\fR, below. .TP \fBinterp\fR \fBhide\fR \fIpath\fR \fIexposedCmdName\fR ?\fIhiddenCmdName\fR? +. Makes the exposed command \fIexposedCmdName\fR hidden, renaming it to the hidden command \fIhiddenCmdName\fR, or keeping the same name if -\fIhiddenCmdName\fR is not given, in the interpreter denoted +\fIhiddenCmdName\fR is not given, in the interpreter denoted by \fIpath\fR. If a hidden command with the targeted name already exists, this command fails. -Currently both \fIexposedCmdName\fR and \fIhiddenCmdName\fR can +Currently both \fIexposedCmdName\fR and \fIhiddenCmdName\fR can not contain namespace qualifiers, or an error is raised. Commands to be hidden by \fBinterp hide\fR are looked up in the global namespace even if the current namespace is not the global one. This @@ -208,41 +292,49 @@ command, by making the current namespace be different from the global one. Hidden commands are explained in more detail in \fBHIDDEN COMMANDS\fR, below. .TP \fBinterp\fR \fBhidden\fR \fIpath\fR +. Returns a list of the names of all hidden commands in the interpreter identified by \fIpath\fR. .TP -\fBinterp\fR \fBinvokehidden\fR \fIpath\fR ?\fB-namespace\fR \fInamespace\fR? ?\fB-global\fR? ?\fB\-\|\-\fR? \fIhiddenCmdName\fR ?\fIarg ...\fR? +\fBinterp\fR \fBinvokehidden\fR \fIpath\fR ?\fI\-option ...\fR? \fIhiddenCmdName\fR ?\fIarg ...\fR? +. Invokes the hidden command \fIhiddenCmdName\fR with the arguments supplied in the interpreter denoted by \fIpath\fR. No substitutions or evaluation -are applied to the arguments. -If the \fB-namespace\fR flag is present, the hidden command is invoked in -the specified namespace in the target interpreter. -If the \fB-global\fR flag is present, the hidden command is invoked at the +are applied to the arguments. Three \fI\-option\fRs are supported, all +of which start with \fB\-\fR: \fB\-namespace\fR (which takes a single +argument afterwards, \fInsName\fR), \fB\-global\fR, and \fB\-\|\-\fR. +If the \fB\-namespace\fR flag is present, the hidden command is invoked in +the namespace called \fInsName\fR in the target interpreter. +If the \fB\-global\fR flag is present, the hidden command is invoked at the global level in the target interpreter; otherwise it is invoked at the current call frame and can access local variables in that and outer call frames. -If both the \fB-namespace\fR and \fB-global\fR flags are present, the -\fB-namespace\fR flag is ignored. +The \fB\-\|\-\fR flag allows the \fIhiddenCmdName\fR argument to start with a +.QW \- +character, and is otherwise unnecessary. +If both the \fB\-namespace\fR and \fB\-global\fR flags are present, the +\fB\-namespace\fR flag is ignored. Note that the hidden command will be executed (by default) in the current context stack frame of the \fIpath\fR interpreter. Hidden commands are explained in more detail in \fBHIDDEN COMMANDS\fR, below. .TP -\fBinterp\fR \fBlimit\fR \fIpath\fR \fIlimitType\fR ?\fIoption\fR? ?\fIvalue\fR \fI...\fR? -.VS 8.5 +\fBinterp issafe\fR ?\fIpath\fR? +. +Returns \fB1\fR if the interpreter identified by the specified \fIpath\fR +is safe, \fB0\fR otherwise. +.TP +\fBinterp\fR \fBlimit\fR \fIpath\fR \fIlimitType\fR ?\fI\-option\fR? ?\fIvalue\fR \fI...\fR? +. Sets up, manipulates and queries the configuration of the resource limit \fIlimitType\fR for the interpreter denoted by \fIpath\fR. If -no \fIoption\fR is specified, return the current configuration of the -limit. If \fIoption\fR is the sole argument, return the value of that -option. Otherwise, a list of \fIoption\fR/\fIvalue\fR argument pairs +no \fI\-option\fR is specified, return the current configuration of the +limit. If \fI\-option\fR is the sole argument, return the value of that +option. Otherwise, a list of \fI\-option\fR/\fIvalue\fR argument pairs must supplied. See \fBRESOURCE LIMITS\fR below for a more detailed explanation of what limits and options are supported. -.VE 8.5 -.TP -\fBinterp issafe\fR ?\fIpath\fR? -Returns \fB1\fR if the interpreter identified by the specified \fIpath\fR -is safe, \fB0\fR otherwise. .TP \fBinterp marktrusted\fR \fIpath\fR +. Marks the interpreter identified by \fIpath\fR as trusted. Does not expose the hidden commands. This command can only be invoked from a trusted interpreter. @@ -250,23 +342,27 @@ The command has no effect if the interpreter identified by \fIpath\fR is already trusted. .TP \fBinterp\fR \fBrecursionlimit\fR \fIpath\fR ?\fInewlimit\fR? +. Returns the maximum allowable nesting depth for the interpreter specified by \fIpath\fR. If \fInewlimit\fR is specified, the interpreter recursion limit will be set so that nesting -of more than \fInewlimit\fR calls to \fBTcl_Eval()\fR +of more than \fInewlimit\fR calls to \fBTcl_Eval\fR and related procedures in that interpreter will return an error. The \fInewlimit\fR value is also returned. The \fInewlimit\fR value must be a positive integer between 1 and the -maximum value of a non-long integer on the platform. -.sp +maximum value of a non-long integer on the platform. +.RS +.PP The command sets the maximum size of the Tcl call stack only. It cannot by itself prevent stack overflows on the C stack being used by the application. If your machine has a limit on the size of the C stack, you may get stack overflows before reaching the limit set by the command. If this happens, see if there is a mechanism in your system for increasing -the maximum size of the C stack. +the maximum size of the C stack. +.RE .TP \fBinterp\fR \fBshare\fR \fIsrcPath channelId destPath\fR +. Causes the IO channel identified by \fIchannelId\fR to become shared between the interpreter identified by \fIsrcPath\fR and the interpreter identified by \fIdestPath\fR. Both interpreters have the same permissions @@ -276,11 +372,13 @@ channels accessible in an interpreter are automatically closed when an interpreter is destroyed. .TP \fBinterp\fR \fBslaves\fR ?\fIpath\fR? +. Returns a Tcl list of the names of all the slave interpreters associated with the interpreter identified by \fIpath\fR. If \fIpath\fR is omitted, the invoking interpreter is used. .TP \fBinterp\fR \fBtarget\fR \fIpath alias\fR +. Returns a Tcl list describing the target interpreter for an alias. The alias is specified with an interpreter path and source command name, just as in \fBinterp alias\fR above. The name of the target interpreter is @@ -291,6 +389,7 @@ invoking interpreter or one of its descendants then an error is generated. The target command does not have to be defined at the time of this invocation. .TP \fBinterp\fR \fBtransfer\fR \fIsrcPath channelId destPath\fR +. Causes the IO channel identified by \fIchannelId\fR to become available in the interpreter identified by \fIdestPath\fR and unavailable in the interpreter identified by \fIsrcPath\fR. @@ -301,20 +400,24 @@ new Tcl command is created in the master interpreter with the same name as the new interpreter. This command may be used to invoke various operations on the interpreter. It has the following general form: +.PP .CS \fIslave command \fR?\fIarg arg ...\fR? .CE +.PP \fISlave\fR is the name of the interpreter, and \fIcommand\fR and the \fIarg\fRs determine the exact behavior of the command. The valid forms of this command are: .TP \fIslave \fBaliases\fR +. Returns a Tcl list whose elements are the tokens of all the aliases in \fIslave\fR. The tokens correspond to the values returned when -the aliases were created (which may not be the same +the aliases were created (which may not be the same as the current names of the commands). .TP \fIslave \fBalias \fIsrcToken\fR +. Returns a Tcl list whose elements are the \fItargetCmd\fR and \fIarg\fRs associated with the alias represented by \fIsrcToken\fR (this is the value returned when the alias was @@ -322,12 +425,14 @@ created; it is possible that the actual source command in the slave is different from \fIsrcToken\fR). .TP \fIslave \fBalias \fIsrcToken \fB{}\fR +. Deletes the alias for \fIsrcToken\fR in the slave interpreter. \fIsrcToken\fR refers to the value returned when the alias was created; if the source command has been renamed, the renamed command will be deleted. .TP \fIslave \fBalias \fIsrcCmd targetCmd \fR?\fIarg ..\fR? +. Creates an alias such that whenever \fIsrcCmd\fR is invoked in \fIslave\fR, \fItargetCmd\fR is invoked in the master. The \fIarg\fR arguments will be passed to \fItargetCmd\fR as additional @@ -338,12 +443,22 @@ The command returns a token that uniquely identifies the command created \fIsrcCmd\fR, even if the command is renamed afterwards. The token may but does not have to be equal to \fIsrcCmd\fR. .TP +\fIslave \fBbgerror\fR ?\fIcmdPrefix\fR? +. +This command either gets or sets the current background exception handler +for the \fIslave\fR interpreter. If \fIcmdPrefix\fR is +absent, the current background exception handler is returned, and if it is +present, it is a list of words (of minimum length one) that describes +what to set the interpreter's background exception handler to. See the +\fBBACKGROUND EXCEPTION HANDLING\fR section for more details. +.TP \fIslave \fBeval \fIarg \fR?\fIarg ..\fR? +. This command concatenates all of the \fIarg\fR arguments in the same fashion as the \fBconcat\fR command, then evaluates the resulting string as a Tcl script in \fIslave\fR. -The result of this evaluation (including error information -such as the \fBerrorInfo\fR and \fBerrorCode\fR variables, if an +The result of this evaluation (including all \fBreturn\fR options, +such as \fB\-errorinfo\fR and \fB\-errorcode\fR information, if an error occurs) is returned to the invoking interpreter. Note that the script will be executed in the current context stack frame of \fIslave\fR; this is so that the implementations (in a master @@ -352,6 +467,7 @@ the slave that find out information about the slave's current state and stack frame. .TP \fIslave \fBexpose \fIhiddenName \fR?\fIexposedCmdName\fR? +. This command exposes the hidden command \fIhiddenName\fR, eventually bringing it back under a new \fIexposedCmdName\fR name (this name is currently accepted only if it is a valid global name space name without any ::), @@ -361,12 +477,13 @@ fails. For more details on hidden commands, see \fBHIDDEN COMMANDS\fR, below. .TP \fIslave \fBhide \fIexposedCmdName\fR ?\fIhiddenCmdName\fR? -This command hides the exposed command \fIexposedCmdName\fR, renaming it to +. +This command hides the exposed command \fIexposedCmdName\fR, renaming it to the hidden command \fIhiddenCmdName\fR, or keeping the same name if the argument is not given, in the \fIslave\fR interpreter. If a hidden command with the targeted name already exists, this command fails. -Currently both \fIexposedCmdName\fR and \fIhiddenCmdName\fR can +Currently both \fIexposedCmdName\fR and \fIhiddenCmdName\fR can not contain namespace qualifiers, or an error is raised. Commands to be hidden are looked up in the global namespace even if the current namespace is not the global one. This @@ -375,59 +492,70 @@ command, by making the current namespace be different from the global one. For more details on hidden commands, see \fBHIDDEN COMMANDS\fR, below. .TP \fIslave \fBhidden\fR +. Returns a list of the names of all hidden commands in \fIslave\fR. .TP -\fIslave \fBinvokehidden\fR ?\fB-namespace\fR \fInamespace\fR? ?\fB-global\fR ?\fB\-\|\-\fR? \fIhiddenName \fR?\fIarg ..\fR? +\fIslave \fBinvokehidden\fR ?\fI\-option ...\fR? \fIhiddenName \fR?\fIarg ..\fR? +. This command invokes the hidden command \fIhiddenName\fR with the supplied arguments, in \fIslave\fR. No substitutions or evaluations are -applied to the arguments. -If the \fB-namespace\fR flag is given, the hidden command is invoked in +applied to the arguments. Three \fI\-option\fRs are supported, all +of which start with \fB\-\fR: \fB\-namespace\fR (which takes a single +argument afterwards, \fInsName\fR), \fB\-global\fR, and \fB\-\|\-\fR. +If the \fB\-namespace\fR flag is given, the hidden command is invoked in the specified namespace in the slave. -If the \fB-global\fR flag is given, the command is invoked at the global +If the \fB\-global\fR flag is given, the command is invoked at the global level in the slave; otherwise it is invoked at the current call frame and can access local variables in that or outer call frames. -If both the \fB-namespace\fR and \fB-global\fR flags are given, the -\fB-namespace\fR flag is ignored. +The \fB\-\|\-\fR flag allows the \fIhiddenCmdName\fR argument to start with a +.QW \- +character, and is otherwise unnecessary. +If both the \fB\-namespace\fR and \fB\-global\fR flags are given, the +\fB\-namespace\fR flag is ignored. Note that the hidden command will be executed (by default) in the current context stack frame of \fIslave\fR. -For more details on hidden commands, +For more details on hidden commands, see \fBHIDDEN COMMANDS\fR, below. .TP \fIslave \fBissafe\fR +. Returns \fB1\fR if the slave interpreter is safe, \fB0\fR otherwise. .TP -\fIslave \fBlimit\fR \fIlimitType\fR ?\fIoption\fR? ?\fIvalue\fR \fI...\fR? -.VS 8.5 +\fIslave \fBlimit\fR \fIlimitType\fR ?\fI\-option\fR? ?\fIvalue\fR \fI...\fR? +. Sets up, manipulates and queries the configuration of the resource -limit \fIlimitType\fR for the slave interpreter. If no \fIoption\fR +limit \fIlimitType\fR for the slave interpreter. If no \fI\-option\fR is specified, return the current configuration of the limit. If -\fIoption\fR is the sole argument, return the value of that option. -Otherwise, a list of \fIoption\fR/\fIvalue\fR argument pairs must +\fI\-option\fR is the sole argument, return the value of that option. +Otherwise, a list of \fI\-option\fR/\fIvalue\fR argument pairs must supplied. See \fBRESOURCE LIMITS\fR below for a more detailed explanation of what limits and options are supported. -.VE 8.5 .TP \fIslave \fBmarktrusted\fR +. Marks the slave interpreter as trusted. Can only be invoked by a trusted interpreter. This command does not expose any hidden commands in the slave interpreter. The command has no effect if the slave is already trusted. .TP \fIslave\fR \fBrecursionlimit\fR ?\fInewlimit\fR? +. Returns the maximum allowable nesting depth for the \fIslave\fR interpreter. If \fInewlimit\fR is specified, the recursion limit in \fIslave\fR will be set so that nesting of more than \fInewlimit\fR calls to \fBTcl_Eval()\fR and related procedures in \fIslave\fR will return an error. The \fInewlimit\fR value is also returned. The \fInewlimit\fR value must be a positive integer between 1 and the -maximum value of a non-long integer on the platform. -.sp +maximum value of a non-long integer on the platform. +.RS +.PP The command sets the maximum size of the Tcl call stack only. It cannot by itself prevent stack overflows on the C stack being used by the application. If your machine has a limit on the size of the C stack, you may get stack overflows before reaching the limit set by the command. If this happens, see if there is a mechanism in your system for increasing -the maximum size of the C stack. +the maximum size of the C stack. +.RE .SH "SAFE INTERPRETERS" .PP A safe interpreter is one with restricted functionality, so that @@ -453,31 +581,33 @@ A safe interpreter is created with exactly the following set of built-in commands: .DS .ta 1.2i 2.4i 3.6i -\fBafter append array binary -break case catch clock -close concat continue eof -error eval expr fblocked -fcopy fileevent flush for -foreach format gets global -if incr info interp -join lappend lindex linsert -list llength lrange lreplace -lsearch lsort namespace package -pid proc puts read -regexp regsub rename return -scan seek set split -string subst switch tell -time trace unset update -uplevel upvar variable vwait -while\fR +\fBafter\fR \fBappend\fR \fBapply\fR \fBarray\fR +\fBbinary\fR \fBbreak\fR \fBcatch\fR \fBchan\fR +\fBclock\fR \fBclose\fR \fBconcat\fR \fBcontinue\fR +\fBdict\fR \fBeof\fR \fBerror\fR \fBeval\fR +\fBexpr\fR \fBfblocked\fR \fBfcopy\fR \fBfileevent\fR +\fBflush\fR \fBfor\fR \fBforeach\fR \fBformat\fR +\fBgets\fR \fBglobal\fR \fBif\fR \fBincr\fR +\fBinfo\fR \fBinterp\fR \fBjoin\fR \fBlappend\fR +\fBlassign\fR \fBlindex\fR \fBlinsert\fR \fBlist\fR +\fBllength\fR \fBlrange\fR \fBlrepeat\fR \fBlreplace\fR +\fBlsearch\fR \fBlset\fR \fBlsort\fR \fBnamespace\fR +\fBpackage\fR \fBpid\fR \fBproc\fR \fBputs\fR +\fBread\fR \fBregexp\fR \fBregsub\fR \fBrename\fR +\fBreturn\fR \fBscan\fR \fBseek\fR \fBset\fR +\fBsplit\fR \fBstring\fR \fBsubst\fR \fBswitch\fR +\fBtell\fR \fBtime\fR \fBtrace\fR \fBunset\fR +\fBupdate\fR \fBuplevel\fR \fBupvar\fR \fBvariable\fR +\fBvwait\fR \fBwhile\fR .DE The following commands are hidden by \fBinterp create\fR when it creates a safe interpreter: .DS .ta 1.2i 2.4i 3.6i -\fBcd encoding exec exit -fconfigure file glob load -open pwd socket source\fR +\fBcd\fR \fBencoding\fR \fBexec\fR \fBexit\fR +\fBfconfigure\fR \fBfile\fR \fBglob\fR \fBload\fR +\fBopen\fR \fBpwd\fR \fBsocket\fR \fBsource\fR +\fBunload\fR .DE These commands can be recreated later as Tcl procedures or aliases, or re-exposed by \fBinterp expose\fR. @@ -486,25 +616,24 @@ The following commands from Tcl's library of support procedures are not present in a safe interpreter: .DS .ta 1.6i 3.2i -\fBauto_exec_ok auto_import auto_load -auto_load_index auto_qualify unknown\fR +\fBauto_exec_ok\fR \fBauto_import\fR \fBauto_load\fR +\fBauto_load_index\fR \fBauto_qualify\fR \fBunknown\fR .DE Note in particular that safe interpreters have no default \fBunknown\fR -command, so Tcl's default autoloading facilities are not available. +command, so Tcl's default autoloading facilities are not available. Autoload access to Tcl's commands that are normally autoloaded: .DS .ta 2.1i -\fB -auto_mkindex auto_mkindex_old -auto_reset history -parray pkg_mkIndex -::pkg::create ::safe::interpAddToAccessPath -::safe::interpCreate ::safe::interpConfigure -::safe::interpDelete ::safe::interpFindInAccessPath -::safe::interpInit ::safe::setLogCmd -tcl_endOfWord tcl_findLibrary -tcl_startOfNextWord tcl_startOfPreviousWord -tcl_wordBreakAfter tcl_wordBreakBefore\fR +\fBauto_mkindex\fR \fBauto_mkindex_old\fR +\fBauto_reset\fR \fBhistory\fR +\fBparray\fR \fBpkg_mkIndex\fR +\fB::pkg::create\fR \fB::safe::interpAddToAccessPath\fR +\fB::safe::interpCreate\fR \fB::safe::interpConfigure\fR +\fB::safe::interpDelete\fR \fB::safe::interpFindInAccessPath\fR +\fB::safe::interpInit\fR \fB::safe::setLogCmd\fR +\fBtcl_endOfWord\fR \fBtcl_findLibrary\fR +\fBtcl_startOfNextWord\fR \fBtcl_startOfPreviousWord\fR +\fBtcl_wordBreakAfter\fR \fBtcl_wordBreakBefore\fR .DE can only be provided by explicit definition of an \fBunknown\fR command in the safe interpreter. This will involve exposing the \fBsource\fR @@ -547,9 +676,10 @@ as they would be for any other command invoked in that interpreter. The command procedure for the source command takes its arguments and merges them with the \fItargetCmd\fR and \fIarg\fRs for the alias to create a new array of arguments. If the words -of \fIsrcCmd\fR were ``\fIsrcCmd arg1 arg2 ... argN\fR'', +of \fIsrcCmd\fR were +.QW "\fIsrcCmd arg1 arg2 ... argN\fR" , the new set of words will be -``\fItargetCmd arg arg ... arg arg1 arg2 ... argN\fR'', +.QW "\fItargetCmd arg arg ... arg arg1 arg2 ... argN\fR" , where \fItargetCmd\fR and \fIarg\fRs are the values supplied when the alias was created. \fITargetCmd\fR is then used to locate a command procedure in the target interpreter, and that command procedure @@ -637,119 +767,144 @@ namespace even if the current namespace is not the global one. This prevents slaves from fooling a master interpreter into hiding the wrong command, by making the current namespace be different from the global one. .SH "RESOURCE LIMITS" -.VS 8.5 -.PP -Every interpreter has two kinds of resource limits that may be imposed -by any master interpreter upon its slaves. Command limits (of type -\fBcommand\fR) restrict the total number of Tcl commands that may be -executed by an interpreter (as can be inspected via the \fBinfo -cmdcount\fR command), and time limits (of type \fBtime\fR) place a -limit by which execution within the interpreter must complete. -.PP -When a limit is exceeded for an interpreter, first any handler -callbacks defined by master interpreters are called. If those -callbacks increase or remove the limit, execution within the -(previously) limited interpreter continues. If the limit is still in -force, an error is generated at that point and normal processing of -errors within the interpreter (by the \fBcatch\fR command) is -disabled, so the error propagates outwards (building a stack-trace as -it goes) to the point where the limited interpreter was invoked -(e.g. by \fBinterp eval\fR) where it becomes the responsibility of the -calling code to catch and handle. -.PP -Every limit has a number of options associated with it, some of which -are common across all kinds of limits, and others of which are -particular to the kind of limit. +.PP +Every interpreter has two kinds of resource limits that may be imposed by any +master interpreter upon its slaves. Command limits (of type \fBcommand\fR) +restrict the total number of Tcl commands that may be executed by an +interpreter (as can be inspected via the \fBinfo cmdcount\fR command), and +time limits (of type \fBtime\fR) place a limit by which execution within the +interpreter must complete. Note that time limits are expressed as +\fIabsolute\fR times (as in \fBclock seconds\fR) and not relative times (as in +\fBafter\fR) because they may be modified after creation. +.PP +When a limit is exceeded for an interpreter, first any handler callbacks +defined by master interpreters are called. If those callbacks increase or +remove the limit, execution within the (previously) limited interpreter +continues. If the limit is still in force, an error is generated at that point +and normal processing of errors within the interpreter (by the \fBcatch\fR +command) is disabled, so the error propagates outwards (building a stack-trace +as it goes) to the point where the limited interpreter was invoked (e.g. by +\fBinterp eval\fR) where it becomes the responsibility of the calling code to +catch and handle. +.SS "LIMIT OPTIONS" +.PP +Every limit has a number of options associated with it, some of which are +common across all kinds of limits, and others of which are particular to the +kind of limit. .TP \fB\-command\fR -This option (common for all limit types) specifies (if non-empty) a -Tcl script to be executed in the global namespace of the interpreter -reading and writing the option when the particular limit in the -limited interpreter is exceeded. The callback may modify the limit on -the interpreter if it wishes the limited interpreter to continue -executing. If the callback generates an error, it is reported through -the background error mechansism (see \fBbgerror\fR). Note that the -callbacks defined by one interpreter are completely isolated from the -callbacks defined by another, and that the order in which those -callbacks are called is undefined. +. +This option (common for all limit types) specifies (if non-empty) a Tcl script +to be executed in the global namespace of the interpreter reading and writing +the option when the particular limit in the limited interpreter is exceeded. +The callback may modify the limit on the interpreter if it wishes the limited +interpreter to continue executing. If the callback generates an exception, it +is reported through the background exception mechanism (see +\fBBACKGROUND EXCEPTION HANDLING\fR). +Note that the callbacks defined by one interpreter are +completely isolated from the callbacks defined by another, and that the order +in which those callbacks are called is undefined. .TP \fB\-granularity\fR -This option (common for all limit types) specifies how frequently (out -of the points when the Tcl interpreter is in a consistent state where -limit checking is possible) that the limit is actually checked. This -allows the tuning of how frequently a limit is checked, and hence how -often the limit-checking overhead (which may be substantial in the -case of time limits) is incurred. +. +This option (common for all limit types) specifies how frequently (out of the +points when the Tcl interpreter is in a consistent state where limit checking +is possible) that the limit is actually checked. This allows the tuning of how +frequently a limit is checked, and hence how often the limit-checking overhead +(which may be substantial in the case of time limits) is incurred. .TP \fB\-milliseconds\fR -This option specifies the number of milliseconds after the moment -defined in the \fB\-seconds\fR option that the time limit will fire. -It should only ever be specified in conjunction with the -\fB\-seconds\fR option (whether it was set previously or is being set -this invokation.) +. +This option specifies the number of milliseconds after the moment defined in +the \fB\-seconds\fR option that the time limit will fire. It should only ever +be specified in conjunction with the \fB\-seconds\fR option (whether it was +set previously or is being set this invocation.) .TP \fB\-seconds\fR -This option specifies the number of seconds after the epoch (see -\fBclock seconds\fR) that the time limit for the interpreter will be -triggered. The limit will be triggered at the start of the second -unless specified at a sub-second level using the \fB\-milliseconds\fR -option. This option may be the empty string, which indicates that a -time limit is not set for the interpreter. +. +This option specifies the number of seconds after the epoch (see \fBclock +seconds\fR) that the time limit for the interpreter will be triggered. The +limit will be triggered at the start of the second unless specified at a +sub-second level using the \fB\-milliseconds\fR option. This option may be the +empty string, which indicates that a time limit is not set for the +interpreter. .TP \fB\-value\fR -This option specifies the number of commands that the interpreter may -execute before triggering the command limit. This option may be the -empty string, which indicates that a command limit is not set for the -interpreter. +. +This option specifies the number of commands that the interpreter may execute +before triggering the command limit. This option may be the empty string, +which indicates that a command limit is not set for the interpreter. .PP Where an interpreter with a resource limit set on it creates a slave -interpreter, that slave interpreter will have resource limits imposed -on it that are at least as restrictive as the limits on the creating -master interpreter. If the master interpreter of the limited master -wishes to relax these conditions, it should hide the \fBinterp\fR -command in the child and then use aliases and the \fBinterp -invokehidden\fR subcommand to provide such access as it chooses to the -\fBinterp\fR command to the limited master as necessary. -.VE 8.5 +interpreter, that slave interpreter will have resource limits imposed on it +that are at least as restrictive as the limits on the creating master +interpreter. If the master interpreter of the limited master wishes to relax +these conditions, it should hide the \fBinterp\fR command in the child and +then use aliases and the \fBinterp invokehidden\fR subcommand to provide such +access as it chooses to the \fBinterp\fR command to the limited master as +necessary. +.SH "BACKGROUND EXCEPTION HANDLING" +.PP +When an exception happens in a situation where it cannot be reported directly up +the stack (e.g. when processing events in an \fBupdate\fR or \fBvwait\fR call) +the exception is instead reported through the background exception handling mechanism. +Every interpreter has a background exception handler registered; the default exception +handler arranges for the \fBbgerror\fR command in the interpreter's global +namespace to be called, but other exception handlers may be installed and process +background exceptions in substantially different ways. +.PP +A background exception handler consists of a non-empty list of words to which will +be appended two further words at invocation time. The first word will be the +interpreter result at time of the exception, typically an error message, +and the second will be the dictionary of return options at the time of +the exception. These are the same values that \fBcatch\fR can capture +when it controls script evaluation in a non-background situation. +The resulting list will then be executed +in the interpreter's global namespace without further substitutions being +performed. .SH CREDITS -This mechanism is based on the Safe-Tcl prototype implemented +The safe interpreter mechanism is based on the Safe-Tcl prototype implemented by Nathaniel Borenstein and Marshall Rose. .SH EXAMPLES +.PP Creating and using an alias for a command in the current interpreter: +.PP .CS \fBinterp alias\fR {} getIndex {} lsearch {alpha beta gamma delta} set idx [getIndex delta] .CE .PP Executing an arbitrary command in a safe interpreter where every -invokation of \fBlappend\fR is logged: +invocation of \fBlappend\fR is logged: +.PP .CS set i [\fBinterp create\fR -safe] \fBinterp hide\fR $i lappend \fBinterp alias\fR $i lappend {} loggedLappend $i proc loggedLappend {i args} { - puts "logged invokation of lappend $args" - \fBinterp invokehidden\fR $i lappend {expand}$args + puts "logged invocation of lappend $args" + \fBinterp invokehidden\fR $i lappend {*}$args } \fBinterp eval\fR $i $someUntrustedScript .CE .PP -.VS 8.5 Setting a resource limit on an interpreter so that an infinite loop terminates. +.PP .CS set i [\fBinterp create\fR] \fBinterp limit\fR $i command -value 1000 \fBinterp eval\fR $i { - set x 0 - while {1} { - puts "Counting up... [incr x]" - } + set x 0 + while {1} { + puts "Counting up... [incr x]" + } } .CE -.VE 8.5 - .SH "SEE ALSO" -load(n), safe(n), Tcl_CreateSlave(3) +bgerror(n), load(n), safe(n), Tcl_CreateSlave(3), Tcl_Eval(3), Tcl_BackgroundException(3) .SH KEYWORDS alias, master interpreter, safe interpreter, slave interpreter +'\"Local Variables: +'\"mode: nroff +'\"End: |