if false {wdb on page tcl9var, we discussed unification of namespaces of commands and variables. Main argument against it was broken compatibility to current variables.
Here a try to use it with source-compatibility to Tcl 8.x:
}
package require Tcl 8.5
# because of dict
namespace eval tcl9var {
variable tcl9val {}
namespace export tcl9var
}
proc tcl9var::handleVar {name {cmd get} args} {
variable tcl9val
if {$cmd in {set unset}} then {
dict $cmd tcl9val $name {*}$args
} else {
dict $cmd $tcl9val $name {*}$args
}
}
proc tcl9var::tcl9var {name args} {
variable tcl9val
set ns [uplevel namespace current]
if {$ns eq "::"} then {
set n ::$name
} else {
set n ${ns}::$name
}
dict set tcl9val $n {*}$args
uplevel 1 [list proc $name args {
::tcl9var::handleVar [
namespace origin [lindex [info level 0] 0]
] {*}$args
}]
$name
}
namespace import tcl9var::tcl9var
if false {As an example, we use a simple variable:
% tcl9var a apple
apple
% puts "my [a] is red"
my apple is red
% a set [a]tree
::obst {a apfel b birne} ::a appletree
% puts "my [a] is high"
my appletree is high
% In one way we can build a variable as a dictionary:
tcl9var fruit
% tcl9var fruit a apple
a apple
% tcl9var fruit o orange
a apple o orange
% fruit
a apple o orange
% fruit get
a apple o orange
% fruit get a
apple
% fruit get o
orange
% fruit set o mango
::a appletree ::fruit {a apple o mango}
% fruit get o
mangoCare must be taken if the "raw value" of a variable has an odd number of elements -- then dict usage fails.
Compatibility issues
With usage as dict, we can introduce a special variable $ internally built as dictionary as follows:
% tcl9var $ start 0
start 0
% tcl9var $ end 10
start 0 end 10
% $ get start
0
% $ get end
10
%
}
if false {Now, the syntax $abc shall shall be expanded by proc expand$ to the appropriate call of variable $ above.
With this expansion of cmd lines, you can make things like $hello, or $hello(world), or $hello(world)(of_tcl_programming), i.e. true multi-dimensional arrays.
}
proc expand$ str {
if {((?:[(].*[)])*)} $str m v b]} then {
return $str
}
set matchStart [string first $m $str]
set matchEnd $matchStart
incr matchEnd [string length $m]
incr matchStart -1
append result [string range $str 0 $matchStart]\
"\[$ get $v"
foreach x [split [string trim [string map {( ""} $b] )] )] {
append result " [list $x]"
}
append result \]\
[expand$ [string range $str $matchEnd end]]
}
if false {Example:
% expand$ {This $a stems from $your(garden)}
This [$ get a] stems from [$ get your garden]
%
% expand$ {test call: $a(b)(c)(d)}
test call: [$ get a b c d]
% An appropriate procedure set can be defined as needed by backwards compatibility.
Consequences: syntax with $ works as usual.
Semantics of dict provided by variable methods. Shorter source code.
Unsolved problems: as $ is a procedure here, it cannot (yet) be local to a proc or apply close. Perhaps subject for a TIP? (I'm not sure.)
}