Subcommand of [dict], used for getting a value out of a dictionary or nested set of dictionaries.
: '''dict get''' ''dict'' ?''key …''?
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[AMG]: Here's a [[dict getnull]] command which returns empty string rather than raise an [error] when the requested element doesn't exist. This example uses [{*}] and [[[namespace ensemble]]]. It also takes advantage of the fact that the return value of [[[if]]] or a [proc] is the return value of the last command it executed, or empty string if it didn't execute anything.
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proc ::tcl::dict::getnull {dictionary args} {
if {[exists $dictionary {*}$args]} {
get $dictionary {*}$args
}
}
namespace ensemble configure dict -map\
[dict replace [namespace ensemble configure dict -map]\
getnull ::tcl::dict::getnull]
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Examples:
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dict getnull {a b c {d e f g}} a ;# b
dict getnull {a b c {d e f g}} c ;# d e f g
dict getnull {a b c {d e f g}} c d ;# e
dict getnull {a b c {d e f g}} c f ;# g
dict getnull {a b c {d e f g}} h ;# (empty string)
dict getnull {a b c {d e f g}} c h ;# (empty string)
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[ufko] Example kv:
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proc kv {lst key} {
set idx [lsearch $lst $key] if {$idx == -1} {
return -1
}
incr idx
return [lindex $lst $idx]
}
set L {id 100 name john}
puts [kv $L id]
set L {id 100 person {firstname Dave lastname Doe}}
puts [kv [kv $L person] lastname]
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See Also: [dict get?]
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