auto-loading of ensemble and stubs on demand only (+ test covered now, see clock-0.1);

introduces new possibility to implement namespace-based auto-loading, e. g.:
    set ::auto_index_ns(::some::namespace) [list ::source [::file join $dir some namespace.tcl]]]

loading of clock-stubs (clock.tcl) implemented via handler "auto_index_ns" now.

2 files changed, 65 insertions, 29 deletions

diff --git a/library/init.tcl b/library/init.tcl
index 824f66f..d2c3b6e 100644
--- a/library/init.tcl
+++ b/library/init.tcl
@@ -156,6 +156,17 @@ if {(![interp issafe]) && ($tcl_platform(platform) eq "windows")} {
 if {[interp issafe]} {
     package unknown {::tcl::tm::UnknownHandler ::tclPkgUnknown}
 } else {
+    # Default known auto_index (avoid loading auto index implicit after interp create):
+    
+    array set ::auto_index {
+	::tcl::tm::UnknownHandler {source [info library]/tm.tcl}
+	::tclPkgUnknown {source [info library]/package.tcl}
+	::history {source [info library]/history.tcl}
+    }
+
+    # The newest possibility to load whole namespace:
+    array set ::auto_index_ns {}
+
     # Set up search for Tcl Modules (TIP #189).
     # and setup platform specific unknown package handlers
     if {$tcl_platform(os) eq "Darwin"
@@ -168,28 +179,19 @@ if {[interp issafe]} {
 
     # Set up the 'clock' ensemble
 
-    namespace eval ::tcl::clock [list variable TclLibDir $::tcl_library]
-
     proc clock args {
 	set cmdmap [dict create]
 	foreach cmd {add clicks format microseconds milliseconds scan seconds configure} {
 	    dict set cmdmap $cmd ::tcl::clock::$cmd
 	}
-	namespace eval ::tcl::clock [list namespace ensemble create -command \
-	    [uplevel 1 [list namespace origin [lindex [info level 0] 0]]] \
+	namespace inscope ::tcl::clock [list namespace ensemble create -command \
+	    [uplevel 1 [list ::namespace origin [::lindex [info level 0] 0]]] \
 	    -map $cmdmap -compile 1]
 
-	# Auto-loading stubs for 'clock.tcl'
-	foreach cmd {mcget LocalizeFormat SetupTimeZone GetSystemTimeZone} {
-	    proc ::tcl::clock::$cmd args {
-		variable TclLibDir
-		source -encoding utf-8 [file join $TclLibDir clock.tcl]
-		return [uplevel 1 [info level 0]]
-	    }
-	}
-
-	return [uplevel 1 [info level 0]]
+	uplevel 1 [info level 0]
     }
+    # Auto-loading stubs for 'clock.tcl'
+    set ::auto_index_ns(::tcl::clock) {::namespace inscope ::tcl::clock {::source [::file join [info library] clock.tcl]}}
 }
 
 # Conditionalize for presence of exec.
@@ -417,18 +419,22 @@ proc unknown args {
 #                       for instance. If not given, namespace current is used.
 
 proc auto_load {cmd {namespace {}}} {
-    global auto_index auto_path
+    global auto_index auto_index_ns auto_path
 
+    # qualify names:
     if {$namespace eq ""} {
 	set namespace [uplevel 1 [list ::namespace current]]
     }
     set nameList [auto_qualify $cmd $namespace]
     # workaround non canonical auto_index entries that might be around
     # from older auto_mkindex versions
-    lappend nameList $cmd
-    foreach name $nameList {
+    if {$cmd ni $nameList} {lappend nameList $cmd}
+    
+    # try to load (and create sub-cmd handler "_sub_load_cmd" for further usage):
+    foreach name $nameList [set _sub_load_cmd {
+    	# via auto_index:
 	if {[info exists auto_index($name)]} {
-	    namespace eval :: $auto_index($name)
+	    namespace inscope :: $auto_index($name)
 	    # There's a couple of ways to look for a command of a given
 	    # name.  One is to use
 	    #    info commands $name
@@ -440,22 +446,31 @@ proc auto_load {cmd {namespace {}}} {
 		return 1
 	    }
 	}
-    }
+	# via auto_index_ns - resolver for the whole namespace loaders
+	if {[set ns [::namespace qualifiers $name]] ni {"" "::"} &&
+	    [info exists auto_index_ns($ns)]
+	} {
+	    # remove handler before loading (prevents several self-recursion cases):
+	    set ldr $auto_index_ns($ns); unset auto_index_ns($ns)
+	    namespace inscope :: $ldr
+	    # if got it:
+	    if {[namespace which -command $name] ne ""} {
+		return 1
+	    }
+	}
+    }]
+    
+    # load auto_index if possible:
     if {![info exists auto_path]} {
 	return 0
     }
-
     if {![auto_load_index]} {
 	return 0
     }
-    foreach name $nameList {
-	if {[info exists auto_index($name)]} {
-	    namespace eval :: $auto_index($name)
-	    if {[namespace which -command $name] ne ""} {
-		return 1
-	    }
-	}
-    }
+
+    # try again (something new could be loaded):
+    foreach name $nameList $_sub_load_cmd
+
     return 0
 }
 
@@ -605,7 +620,7 @@ proc auto_import {pattern} {
 	foreach name [array names auto_index $pattern] {
 	    if {([namespace which -command $name] eq "")
 		    && ([namespace qualifiers $pattern] eq [namespace qualifiers $name])} {
-		namespace eval :: $auto_index($name)
+		namespace inscope :: $auto_index($name)
 	    }
 	}
     }
diff --git a/tests/clock.test b/tests/clock.test
index 0737558..af517c8 100644
--- a/tests/clock.test
+++ b/tests/clock.test
@@ -35,6 +35,9 @@ testConstraint y2038 \
 
 # TEST PLAN
 
+# clock-0:
+#	several base test-cases
+#
 # clock-1:
 #	[clock format] - tests of bad and empty arguments
 #
@@ -251,6 +254,24 @@ proc ::testClock::registry { cmd path key } {
     return [dict get $reg $path $key]
 }
 
+# Base test cases:
+
+test clock-0.1 "initial: auto-loading of ensemble and stubs on demand" {
+    set i [interp create]; # because clock can be used somewhere, test it in new interp:
+
+    set ret [$i eval {
+
+	lappend ret ens:[namespace ensemble exists ::clock]
+	clock seconds; # init ensemble (but not yet stubs, loading of clock.tcl retarded)
+	lappend ret ens:[namespace ensemble exists ::clock]
+	lappend ret stubs:[expr {[namespace which -command ::tcl::clock::GetSystemTimeZone] ne ""}]
+	clock format -now; # clock.tcl stubs expected
+	lappend ret stubs:[expr {[namespace which -command ::tcl::clock::GetSystemTimeZone] ne ""}]
+    }]
+    interp delete $i
+    set ret
+} {ens:0 ens:1 stubs:0 stubs:1}
+
 # Test some of the basics of [clock format]
 
 test clock-1.0 "clock format - wrong # args" {