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Gestalt Items |
Copyright © 2008, 2009 Arndt Roger Schneider
wrapper around foreach … break sequences.
seteach {a b} [list 1 2]
# replaces: foreach {a b} [list 1 2] break
…
set a ➠ 1
set b ➠ 2
Seteach does also support nested lists.
Example 9.6. Seteach with nested Lists
seteach {{{a b} c} {d e} f} \
[list [list [list 1 2] 3] [list 4 5]]
…
a ➟1, b ➟2, c ➟3, d ➟4, e ➟5, f nothing.Seteach always expects the same amount of
values and variables –for security reasons.
That is seteach {a b} 1; produces
a variable »a b« with the value »1«. And
seteach {a b c} {1 2} produces a variable
»a b c« with the value »1 2«.
The nested list extension over the
simple foreach … break was written
to support tkpath::mmult.
On foreach .. break: break alters the
control flux inside of an application. Using such a
keyword in a conventional expression, makes it a
commonplace figure inside the source code; obscuring
where it alters the flux. This is highly
dangerous and therefore »seteach« exist.
Seteach accepts an optional argument »format«. The value for -format is a format string.
Example 9.7. seteach with format
seteach {x y} {x y} -format {winfo %s .}
➟ x := window x position of ».«
y := window y position of ».«
Format can be used during navigation. The format string must return exact the same atoms as expected by the variable definition.
Example 9.8. Forbidden format usage
set mylist {{1 2} x y z {3 4 f o r b i d d e n}}
seteach {
{x y} {v w}
} {0 end} -format {lindex $mylist %s}
➟ {v w} := {3 4 f o r b i d d e n} ;# error
x := 1
y := 2
# The end item has 11 atoms and
# only two are expected.
Navigation through encapsulated lists requires, that the amount of atoms inside the sublist is identical to the number of expected replacements.