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Postings from September 2005
Tcl's [expr] command now compiles expressions to PIR (before, it
would create an AST that it would then interpret when you wanted the
value.). Note: the language itself is still interpreted, this is only
one command in the language.
E.g: given a command like
while {$a < 10} {incr $a}
Originally, the while would parse the $a < 10 expression once, then
interpret it (walk through the AST and generate a value) each time.
Now, it compiles the expression to PIR once:
.pragma n_operators 1
.sub blah @ANON
.local pmc read
read=find_global "_Tcl", "__read"
.local pmc number
number=find_global "_Tcl", "__number"
$P0 = read("a")
$P0 = number($P0)
$P1 = new .TclInt
$P1=10
$I2 = islt $P0, $P1
$P2 = new .TclInt
$P2= $I2
.return ($P2)
.end
and then just invokes it when it wants the current value.
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