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Diffstat (limited to 'doc/namespace.n')
| -rw-r--r-- | doc/namespace.n | 271 |
1 files changed, 186 insertions, 85 deletions
diff --git a/doc/namespace.n b/doc/namespace.n index ddf7b51..a32c2f3 100644 --- a/doc/namespace.n +++ b/doc/namespace.n @@ -26,6 +26,7 @@ The legal values of \fIsubcommand\fR are listed below. Note that you can abbreviate the \fIsubcommand\fRs. .TP \fBnamespace children \fR?\fInamespace\fR? ?\fIpattern\fR? +. Returns a list of all child namespaces that belong to the namespace \fInamespace\fR. If \fInamespace\fR is not specified, @@ -41,6 +42,7 @@ otherwise the namespace \fInamespace\fR is prepended onto the pattern. .TP \fBnamespace code \fIscript\fR +. Captures the current namespace context for later execution of the script \fIscript\fR. It returns a new script in which \fIscript\fR has been wrapped @@ -68,6 +70,7 @@ See the section \fBSCOPED SCRIPTS\fR for some examples of how this is used to create callback scripts. .TP \fBnamespace current\fR +. Returns the fully-qualified name for the current namespace. The actual name of the global namespace is .MT @@ -76,6 +79,7 @@ but this command returns \fB::\fR for the global namespace as a convenience to programmers. .TP \fBnamespace delete \fR?\fInamespace namespace ...\fR? +. Each namespace \fInamespace\fR is deleted and all variables, procedures, and child namespaces contained in the namespace are deleted. @@ -87,13 +91,13 @@ If a namespace does not exist, this command returns an error. If no namespace names are given, this command does nothing. .TP \fBnamespace ensemble\fR \fIsubcommand\fR ?\fIarg ...\fR? -.VS 8.5 +. Creates and manipulates a command that is formed out of an ensemble of subcommands. See the section \fBENSEMBLES\fR below for further details. -.VE 8.5 .TP \fBnamespace eval\fR \fInamespace arg\fR ?\fIarg ...\fR? +. Activates a namespace called \fInamespace\fR and evaluates some code in that context. If the namespace does not already exist, it is created. @@ -109,10 +113,12 @@ they are automatically created. .RE .TP \fBnamespace exists\fR \fInamespace\fR +. Returns \fB1\fR if \fInamespace\fR is a valid namespace in the current context, returns \fB0\fR otherwise. .TP -\fBnamespace export \fR?\-\fBclear\fR? ?\fIpattern pattern ...\fR? +\fBnamespace export \fR?\fB\-clear\fR? ?\fIpattern pattern ...\fR? +. Specifies which commands are exported from a namespace. The exported commands are those that can be later imported into another namespace using a \fBnamespace import\fR command. @@ -133,6 +139,7 @@ If no \fIpattern\fRs are given and the \fB\-clear\fR flag is not given, this command returns the namespace's current export list. .TP \fBnamespace forget \fR?\fIpattern pattern ...\fR? +. Removes previously imported commands from a namespace. Each \fIpattern\fR is a simple or qualified name such as \fBx\fR, \fBfoo::x\fR or \fBa::b::p*\fR. @@ -157,7 +164,7 @@ If so, this command deletes the corresponding imported commands. In effect, this un-does the action of a \fBnamespace import\fR command. .TP \fBnamespace import \fR?\fB\-force\fR? ?\fIpattern\fR \fIpattern ...\fR? -.VS 8.5 +. Imports commands into a namespace, or queries the set of imported commands in a namespace. When no arguments are present, \fBnamespace import\fR returns the list of commands in @@ -166,7 +173,8 @@ namespaces. The commands in the returned list are in the format of simple names, with no namespace qualifiers at all. This format is suitable for composition with \fBnamespace forget\fR (see \fBEXAMPLES\fR below). -.VE 8.5 +.RS +.PP When \fIpattern\fR arguments are present, each \fIpattern\fR is a qualified name like \fBfoo::x\fR or \fBa::p*\fR. @@ -174,6 +182,11 @@ That is, it includes the name of an exporting namespace and may have glob-style special characters in the command name at the end of the qualified name. Glob characters may not appear in a namespace name. +When the namespace name is not fully qualified (i.e., does not start +with a namespace separator) it is resolved as a namespace name in the +way described in the \fBNAME RESOLUTION\fR section; it is an error if +no namespace with that name can be found. +.PP All the commands that match a \fIpattern\fR string and which are currently exported from their namespace are added to the current namespace. @@ -182,7 +195,7 @@ that points to the exported command in its original namespace; when the new imported command is called, it invokes the exported command. This command normally returns an error if an imported command conflicts with an existing command. -However, if the \-\fBforce\fR option is given, +However, if the \fB\-force\fR option is given, imported commands will silently replace existing commands. The \fBnamespace import\fR command has snapshot semantics: that is, only requested commands that are currently defined @@ -191,8 +204,10 @@ In other words, you can import only the commands that are in a namespace at the time when the \fBnamespace import\fR command is executed. If another command is defined and exported in this namespace later on, it will not be imported. +.RE .TP \fBnamespace inscope\fR \fInamespace\fR \fIscript\fR ?\fIarg ...\fR? +. Executes a script in the context of the specified \fInamespace\fR. This command is not expected to be used directly by programmers; calls to it are generated implicitly when applications @@ -207,15 +222,19 @@ as proper list elements. .CS \fBnamespace inscope ::foo $script $x $y $z\fR .CE +.PP is equivalent to +.PP .CS \fBnamespace eval ::foo [concat $script [list $x $y $z]]\fR .CE +.PP thus additional arguments will not undergo a second round of substitution, as is the case with \fBnamespace eval\fR. .RE .TP \fBnamespace origin \fIcommand\fR +. Returns the fully-qualified name of the original command to which the imported command \fIcommand\fR refers. When a command is imported into a namespace, @@ -230,23 +249,23 @@ If \fIcommand\fR does not refer to an imported command, the command's own fully-qualified name is returned. .TP \fBnamespace parent\fR ?\fInamespace\fR? +. Returns the fully-qualified name of the parent namespace for namespace \fInamespace\fR. If \fInamespace\fR is not specified, the fully-qualified name of the current namespace's parent is returned. .TP \fBnamespace path\fR ?\fInamespaceList\fR? -.\" Should really have the .TP inside the .VS, but that triggers a groff bug -.VS 8.5 +. Returns the command resolution path of the current namespace. If \fInamespaceList\fR is specified as a list of named namespaces, the current namespace's command resolution path is set to those namespaces and returns the empty list. The default command resolution path is always empty. See the section \fBNAME RESOLUTION\fR below for an explanation of the rules regarding name resolution. -.VE 8.5 .TP \fBnamespace qualifiers\fR \fIstring\fR +. Returns any leading namespace qualifiers for \fIstring\fR. Qualifiers are namespace names separated by double colons (\fB::\fR). For the \fIstring\fR \fB::foo::bar::x\fR, @@ -258,6 +277,7 @@ namespace names are, in fact, the names of currently defined namespaces. .TP \fBnamespace tail\fR \fIstring\fR +. Returns the simple name at the end of a qualified string. Qualifiers are namespace names separated by double colons (\fB::\fR). For the \fIstring\fR \fB::foo::bar::x\fR, @@ -267,8 +287,9 @@ This command is the complement of the \fBnamespace qualifiers\fR command. It does not check whether the namespace names are, in fact, the names of currently defined namespaces. .TP -\fBnamespace upvar\fR \fInamespace\fR \fIotherVar myVar \fR?\fIotherVar myVar \fR... -This command arranges for one or more local variables in the current +\fBnamespace upvar\fR \fInamespace\fR ?\fIotherVar myVar \fR... +. +This command arranges for zero or more local variables in the current procedure to refer to variables in \fInamespace\fR. The namespace name is resolved as described in section \fBNAME RESOLUTION\fR. The command @@ -278,9 +299,11 @@ used for qualified namespace or variable names. \fBnamespace upvar\fR returns an empty string. .TP \fBnamespace unknown\fR ?\fIscript\fR? +. Sets or returns the unknown command handler for the current namespace. The handler is invoked when a command called from within the namespace -cannot be found (in either the current namespace or the global namespace). +cannot be found in the current namespace, the namespace's path nor in +the global namespace. The \fIscript\fR argument, if given, should be a well formed list representing a command name and optional arguments. When the handler is invoked, the full invocation line will be appended to the @@ -288,7 +311,8 @@ script and the result evaluated in the context of the namespace. The default handler for all namespaces is \fB::unknown\fR. If no argument is given, it returns the handler for the current namespace. .TP -\fBnamespace which\fR ?\-\fBcommand\fR? ?\-\fBvariable\fR? \fIname\fR +\fBnamespace which\fR ?\fB\-command\fR? ?\fB\-variable\fR? \fIname\fR +. Looks up \fIname\fR as either a command or variable and returns its fully-qualified name. For example, if \fIname\fR does not exist in the current namespace @@ -312,17 +336,19 @@ which we refer to as the \fIglobal namespace\fR. The global namespace holds all global variables and commands. The \fBnamespace eval\fR command lets you create new namespaces. For example, +.PP .CS \fBnamespace eval\fR Counter { - \fBnamespace export\fR bump - variable num 0 + \fBnamespace export\fR bump + variable num 0 - proc bump {} { - variable num - incr num - } + proc bump {} { + variable num + incr num + } } .CE +.PP creates a new namespace containing the variable \fBnum\fR and the procedure \fBbump\fR. The commands and variables in this namespace are separate from @@ -342,23 +368,25 @@ so you can build up the contents of a namespace over time using a series of \fBnamespace eval\fR commands. For example, the following series of commands has the same effect as the namespace definition shown above: +.PP .CS \fBnamespace eval\fR Counter { - variable num 0 - proc bump {} { - variable num - return [incr num] - } + variable num 0 + proc bump {} { + variable num + return [incr num] + } } \fBnamespace eval\fR Counter { - proc test {args} { - return $args - } + proc test {args} { + return $args + } } \fBnamespace eval\fR Counter { - rename test "" + rename test "" } .CE +.PP Note that the \fBtest\fR procedure is added to the \fBCounter\fR namespace, and later removed via the \fBrename\fR command. .PP @@ -390,19 +418,24 @@ you must use some extra syntax. Names must be qualified by the namespace that contains them. From the global namespace, we might access the \fBCounter\fR procedures like this: +.PP .CS Counter::bump 5 Counter::Reset .CE +.PP We could access the current count like this: +.PP .CS puts "count = $Counter::num" .CE +.PP When one namespace contains another, you may need more than one qualifier to reach its elements. If we had a namespace \fBFoo\fR that contained the namespace \fBCounter\fR, you could invoke its \fBbump\fR procedure from the global namespace like this: +.PP .CS Foo::Counter::bump 3 .CE @@ -410,10 +443,13 @@ Foo::Counter::bump 3 You can also use qualified names when you create and rename commands. For example, you could add a procedure to the \fBFoo\fR namespace like this: +.PP .CS proc Foo::Test {args} {return $args} .CE +.PP And you could move the same procedure to another namespace like this: +.PP .CS rename Foo::Test Bar::Test .CE @@ -440,43 +476,46 @@ you mean. However, if the name does not start with a \fB::\fR (i.e., is \fIrelative\fR), Tcl follows basic rules for looking it up: -Variable names are always resolved -by looking first in the current namespace, -and then in the global namespace. -.VS 8.5 -Command names are also always resolved by looking in the current -namespace first. If not found there, they are searched for in every -namespace on the current namespace's command path (which is empty by -default). If not found there, command names are looked up in the -global namespace (or, failing that, are processed by the \fBunknown\fR -command.) -.VE 8.5 -Namespace names, on the other hand, are always resolved -by looking in only the current namespace. +.IP \(bu +\fBVariable names\fR are always resolved by looking first in the current +namespace, and then in the global namespace. +.IP \(bu +\fBCommand names\fR are always resolved by looking in the current namespace +first. If not found there, they are searched for in every namespace on the +current namespace's command path (which is empty by default). If not found +there, command names are looked up in the global namespace (or, failing that, +are processed by the appropriate \fBnamespace unknown\fR handler.) +.IP \(bu +\fBNamespace names\fR are always resolved by looking in only the current +namespace. .PP In the following example, +.PP .CS set traceLevel 0 \fBnamespace eval\fR Debug { - printTrace $traceLevel + printTrace $traceLevel } .CE +.PP Tcl looks for \fBtraceLevel\fR in the namespace \fBDebug\fR and then in the global namespace. It looks up the command \fBprintTrace\fR in the same way. If a variable or command name is not found in either context, the name is undefined. To make this point absolutely clear, consider the following example: +.PP .CS set traceLevel 0 \fBnamespace eval\fR Foo { - variable traceLevel 3 + variable traceLevel 3 - \fBnamespace eval\fR Debug { - printTrace $traceLevel - } + \fBnamespace eval\fR Debug { + printTrace $traceLevel + } } .CE +.PP Here Tcl looks for \fBtraceLevel\fR first in the namespace \fBFoo::Debug\fR. Since it is not found there, Tcl then looks for it in the global namespace. @@ -486,14 +525,18 @@ during the name resolution process. You can use the \fBnamespace which\fR command to clear up any question about name resolution. For example, the command: +.PP .CS \fBnamespace eval\fR Foo::Debug {\fBnamespace which\fR \-variable traceLevel} .CE +.PP returns \fB::traceLevel\fR. On the other hand, the command, +.PP .CS \fBnamespace eval\fR Foo {\fBnamespace which\fR \-variable traceLevel} .CE +.PP returns \fB::Foo::traceLevel\fR. .PP As mentioned above, @@ -531,23 +574,29 @@ that it is a nuisance to type their qualified names. For example, suppose that all of the commands in a package like BLT are contained in a namespace called \fBBlt\fR. Then you might access these commands like this: +.PP .CS Blt::graph .g \-background red Blt::table . .g 0,0 .CE +.PP If you use the \fBgraph\fR and \fBtable\fR commands frequently, you may want to access them without the \fBBlt::\fR prefix. You can do this by importing the commands into the current namespace, like this: +.PP .CS \fBnamespace import\fR Blt::* .CE +.PP This adds all exported commands from the \fBBlt\fR namespace into the current namespace context, so you can write code like this: +.PP .CS graph .g \-background red table . .g 0,0 .CE +.PP The \fBnamespace import\fR command only imports commands from a namespace that that namespace exported with a \fBnamespace export\fR command. @@ -556,9 +605,11 @@ Importing \fIevery\fR command from a namespace is generally a bad idea since you do not know what you will get. It is better to import just the specific commands you need. For example, the command +.PP .CS \fBnamespace import\fR Blt::graph Blt::table .CE +.PP imports only the \fBgraph\fR and \fBtable\fR commands into the current context. .PP @@ -569,57 +620,67 @@ you may want to get around this restriction. You may want to reissue the \fBnamespace import\fR command to pick up new commands that have appeared in a namespace. In that case, you can use the \fB\-force\fR option, and existing commands will be silently overwritten: +.PP .CS \fBnamespace import\fR \-force Blt::graph Blt::table .CE +.PP If for some reason, you want to stop using the imported commands, you can remove them with a \fBnamespace forget\fR command, like this: +.PP .CS \fBnamespace forget\fR Blt::* .CE +.PP This searches the current namespace for any commands imported from \fBBlt\fR. If it finds any, it removes them. Otherwise, it does nothing. After this, the \fBBlt\fR commands must be accessed with the \fBBlt::\fR prefix. .PP When you delete a command from the exporting namespace like this: +.PP .CS rename Blt::graph "" .CE +.PP the command is automatically removed from all namespaces that import it. .SH "EXPORTING COMMANDS" You can export commands from a namespace like this: +.PP .CS \fBnamespace eval\fR Counter { - \fBnamespace export\fR bump reset - variable Num 0 - variable Max 100 + \fBnamespace export\fR bump reset + variable Num 0 + variable Max 100 - proc bump {{by 1}} { - variable Num - incr Num $by - Check - return $Num - } - proc reset {} { - variable Num - set Num 0 - } - proc Check {} { - variable Num - variable Max - if {$Num > $Max} { - error "too high!" - } - } + proc bump {{by 1}} { + variable Num + incr Num $by + Check + return $Num + } + proc reset {} { + variable Num + set Num 0 + } + proc Check {} { + variable Num + variable Max + if {$Num > $Max} { + error "too high!" + } + } } .CE +.PP The procedures \fBbump\fR and \fBreset\fR are exported, so they are included when you import from the \fBCounter\fR namespace, like this: +.PP .CS \fBnamespace import\fR Counter::* .CE +.PP However, the \fBCheck\fR procedure is not exported, so it is ignored by the import operation. .PP @@ -640,13 +701,13 @@ namespace: .PP .CS \fBnamespace eval\fR a { - variable b - proc theTraceCallback { n1 n2 op } { - upvar 1 $n1 var - puts "the value of $n1 has changed to $var" - return - } - trace add variable b write [\fBnamespace code\fR theTraceCallback] + variable b + proc theTraceCallback { n1 n2 op } { + upvar 1 $n1 var + puts "the value of $n1 has changed to $var" + return + } + trace add variable b write [\fBnamespace code\fR theTraceCallback] } set a::b c .CE @@ -658,7 +719,6 @@ the value of a::b has changed to c .CE .SH ENSEMBLES .PP -.VS 8.5 The \fBnamespace ensemble\fR is used to create and manipulate ensemble commands, which are commands formed by grouping subcommands together. The commands typically come from the current namespace when the @@ -672,6 +732,7 @@ namespace is maintained however the ensemble is renamed. Three subcommands of the \fBnamespace ensemble\fR command are defined: .TP \fBnamespace ensemble create\fR ?\fIoption value ...\fR? +. Creates a new ensemble command linked to the current namespace, returning the fully qualified name of the command created. The arguments to \fBnamespace ensemble create\fR allow the configuration @@ -682,12 +743,14 @@ namespace. See the section \fBENSEMBLE OPTIONS\fR below for a full list of options supported and their effects. .TP \fBnamespace ensemble configure \fIcommand\fR ?\fIoption\fR? ?\fIvalue ...\fR? +. Retrieves the value of an option associated with the ensemble command named \fIcommand\fR, or updates some options associated with that ensemble command. See the section \fBENSEMBLE OPTIONS\fR below for a full list of options supported and their effects. .TP \fBnamespace ensemble exists\fR \fIcommand\fR +. Returns a boolean value that describes whether the command \fIcommand\fR exists and is an ensemble command. This command only ever returns an error if the number of arguments to the command is @@ -710,6 +773,7 @@ create\fR and \fBnamespace ensemble configure\fR commands, control how an ensemble command behaves: .TP \fB\-map\fR +. When non-empty, this option supplies a dictionary that provides a mapping from subcommand names to a list of prefix words to substitute in place of the ensemble command and subcommand words (in a manner @@ -720,13 +784,23 @@ name. Note that when this option is non-empty and the \fB\-subcommands\fR option is empty, the ensemble subcommand names will be exactly those words that have mappings in the dictionary. .TP +\fB\-parameters\fR +.VS 8.6 +This option gives a list of named arguments (the names being used during +generation of error messages) that are passed by the caller of the ensemble +between the name of the ensemble and the subcommand argument. By default, it +is the empty list. +.VE 8.6 +.TP \fB\-prefixes\fR +. This option (which is enabled by default) controls whether the ensemble command recognizes unambiguous prefixes of its subcommands. When turned off, the ensemble command requires exact matching of subcommand names. .TP \fB\-subcommands\fR +. When non-empty, this option lists exactly what subcommands are in the ensemble. The mapping for each of those commands will be either whatever is defined in the \fB\-map\fR option, or to the command with the same @@ -737,6 +811,7 @@ of the linked namespace at the time of the invocation of the ensemble command. .TP \fB\-unknown\fR +. When non-empty, this option provides a partial command (to which all the words that are arguments to the ensemble command, including the fully-qualified name of the ensemble, are appended) to handle the case @@ -750,6 +825,7 @@ The following extra option is allowed by \fBnamespace ensemble create\fR: .TP \fB\-command\fR +. This write-only option allows the name of the ensemble created by \fBnamespace ensemble create\fR to be anything in any existing namespace. The default value for this option is the fully-qualified @@ -760,6 +836,7 @@ The following extra option is allowed by \fBnamespace ensemble configure\fR: .TP \fB\-namespace\fR +. This read-only option allows the retrieval of the fully-qualified name of the namespace which the ensemble was created within. .SS "UNKNOWN HANDLER BEHAVIOUR" @@ -811,29 +888,30 @@ error message from \fBTcl_GetIndexFromObj\fR). This is the error that will be thrown when the subcommand is still not recognized during reparsing. It is also an error for an \fB\-unknown\fR handler to delete its namespace. -.VE 8.5 .SH EXAMPLES Create a namespace containing a variable and an exported command: +.PP .CS \fBnamespace eval\fR foo { - variable bar 0 - proc grill {} { - variable bar - puts "called [incr bar] times" - } - \fBnamespace export\fR grill + variable bar 0 + proc grill {} { + variable bar + puts "called [incr bar] times" + } + \fBnamespace export\fR grill } .CE .PP Call the command defined in the previous example in various ways. +.PP .CS # Direct call ::foo::grill # Use the command resolution path to find the name \fBnamespace eval\fR boo { - \fBnamespace path\fR ::foo - grill + \fBnamespace path\fR ::foo + grill } # Import into current namespace, then call local alias @@ -843,23 +921,46 @@ grill # Create two ensembles, one with the default name and one with a # specified name. Then call through the ensembles. \fBnamespace eval\fR foo { - \fBnamespace ensemble\fR create - \fBnamespace ensemble\fR create -command ::foobar + \fBnamespace ensemble\fR create + \fBnamespace ensemble\fR create -command ::foobar } foo grill foobar grill .CE .PP Look up where the command imported in the previous example came from: +.PP .CS puts "grill came from [\fBnamespace origin\fR grill]" .CE .PP Remove all imported commands from the current namespace: +.PP .CS namespace forget {*}[namespace import] .CE +.PP +.VS 8.6 +Create an ensemble for simple working with numbers, using the +\fB\-parameters\fR option to allow the operator to be put between the first +and second arguments. +.PP +.CS +\fBnamespace eval\fR do { + \fBnamespace export\fR * + \fBnamespace ensemble\fR create -parameters x + proc plus {x y} {expr { $x + $y }} + proc minus {x y} {expr { $x - $y }} +} + +# In use, the ensemble works like this: +puts [do 1 plus [do 9 minus 7]] +.CE +.VE 8.6 .SH "SEE ALSO" interp(n), upvar(n), variable(n) .SH KEYWORDS command, ensemble, exported, internal, variable +'\" Local Variables: +'\" mode: nroff +'\" End: |