Updated 2015-11-15 03:44:41 by pooryorick

dict unset removes a key and its associated value from a dictionary of dictionaries.

Attributes  edit

from Tcl version
8.5

Synopsis  edit

dict unset dictVarName key ?key?

Description  edit

dict unset unsets one element from the dictionary of dictionaries named dictVarName. They key arguments form a path to the key to unset. The variable is modified, and its new value is returned. If the given key doesn't exist in the dict, no change is made. If a key path is given, all keys except the last must exist.
% # Simple example:
% set data {a 1 b 2}
a 1 b 2
% dict unset data a ;# Remove key "a" and its corresponding value "1"
b 2
% set data ;# Verify that variable is modified.
b 2
% dict unset data nonexistent ;# Check nonexistent key handling
b 2
% # Example using nested dicts:
% set data {row1 {col1 val11 col2 val12} row2 {col1 val21 col2 val22}}
row1 {col1 val11 col2 val12} row2 {col1 val21 col2 val22}
% dict unset data row2 col2 ;# Remove element "col2" in nested dict "row2"
row1 {col1 val11 col2 val12} row2 {col1 val21}
% dict unset data row1 ;# Remove element "row1"
row2 {col1 val21}
% set data ;# Verify again that variable is modified
row2 {col1 val21}
% dict unset data row2 col2 ;# Check nonexistent key handling
row2 {col1 val21}
% dict unset data row1 col2 ;# Check nonexistent nested dict handling
key "row1" not known in dictionary

A synonym for
dict unset dictname key

is
dict update dictname key key {unset key}