Tcl Built-In Commands - dict manual page

Performs one of several operations on dictionary values or variables containing dictionary values, depending on option. The legal options (which may be abbreviated) are:

dict append dictionaryVariable key ?string ...?

This appends the given string (or strings) to the value that the given key maps to in the dictionary value contained in the given variable, writing the resulting dictionary value back to that variable. Non-existent keys are treated as if they map to an empty string.

dict create ?key value ...?

Create a new dictionary that contains each of the key/value mappings listed as arguments (keys and values alternating, with each key being followed by its associated value.)

dict exists dictionaryValue key ?key ...?

This returns a boolean value indicating whether the given key (or path of keys through a set of nested dictionaries) exists in the given dictionary value. This returns a true value exactly when dict get on that path will succeed.

dict filter dictionaryValue filterType arg ?arg ...?

This takes a dictionary value and returns a new dictionary that contains just those key/value pairs that match the specified filter type (which may be abbreviated.) Supported filter types are:

dict filter dictionaryValue key globPattern: The key rule only matches those key/value pairs whose keys match the given pattern (in the style of string match.)
dict filter dictionaryValue script {keyVar valueVar} script: The script rule tests for matching by assigning the key to the keyVar and the value to the valueVar, and then evaluating the given script which should return a boolean value (with the key/value pair only being included in the result of the dict filter when a true value is returned.) Note that the first argument after the rule selection word is a two-element list. If the script returns with a condition of TCL_BREAK, no further key/value pairs are considered for inclusion in the resulting dictionary, and a condition of TCL_CONTINUE is equivalent to a false result.
dict filter dictionaryValue value globPattern: The value rule only matches those key/value pairs whose values match the given pattern (in the style of string match.)

dict for {keyVar valueVar} dictionaryValue body

This command takes three arguments, the first a two-element list of variable names (for the key and value respectively of each mapping in the dictionary), the second the dictionary value to iterate across, and the third a script to be evaluated for each mapping with the key and value variables set appropriately (in the manner of foreach.) The result of the command is an empty string. If any evaluation of the body generates a TCL_BREAK result, no further pairs from the dictionary will be iterated over and the dict for command will terminate successfully immediately. If any evaluation of the body generates a TCL_CONTINUE result, this shall be treated exactly like a normal TCL_OK result. The order of iteration is undefined.

dict get dictionaryValue ?key ...?

Given a dictionary value (first argument) and a key (second argument), this will retrieve the value for that key. Where several keys are supplied, the behaviour of the command shall be as if the result of dict get $dictVal $key was passed as the first argument to dict get with the remaining arguments as second (and possibly subsequent) arguments. This facilitates lookups in nested dictionaries. For example, the following two commands are equivalent:

dict get $dict foo bar spong
dict get [dict get [dict get $dict foo] bar] spong

If no keys are provided, dict would return a list containing pairs of elements in a manner similar to array get. That is, the first element of each pair would be the key and the second element would be the value for that key. It is an error to attempt to retrieve a value for a key that is not present in the dictionary.

dict incr dictionaryVariable key ?increment?

This adds the given increment value (an integer that defaults to 1 if not specified) to the value that the given key maps to in the dictionary value contained in the given variable, writing the resulting dictionary value back to that variable. Non-existent keys are treated as if they map to 0. It is an error to increment a value for an existing key if that value is not an integer.

dict info dictionaryValue

This returns information (intended for display to people) about the given dictionary though the format of this data is dependent on the implementation of the dictionary. For dictionaries that are implemented by hash tables, it is expected that this will return the string produced by Tcl_HashStats, similar to array info.

dict keys dictionaryValue ?globPattern?

Return a list of all keys in the given dictionary value. If a pattern is supplied, only those keys that match it (according to the rules of string match) will be returned. The returned keys will be in an arbitrary implementation-specific order, though where no pattern is supplied the i'th key returned by dict keys will be the key for the i'th value returned by dict values applied to the same dictionary value.

dict lappend dictionaryVariable key ?value ...?

This appends the given items to the list value that the given key maps to in the dictionary value contained in the given variable, writing the resulting dictionary value back to that variable. Non-existent keys are treated as if they map to an empty list, and it is legal for there to be no items to append to the list. It is an error for the value that the key maps to to not be representable as a list.

dict remove dictionaryValue ?key ...?

Return a new dictionary that is a copy of an old one passed in as first argument except without mappings for each of the keys listed. It is legal for there to be no keys to remove, and it also legal for any of the keys to be removed to not be present in the input dictionary in the first place.

dict replace dictionaryValue ?key value ...?

Return a new dictionary that is a copy of an old one passed in as first argument except with some values different or some extra key/value pairs added. It is legal for this command to be called with no key/value pairs, but illegal for this command to be called with a key but no value.

dict set dictionaryVariable key ?key ...? value

This operation takes the name of a variable containing a dictionary value and places an updated dictionary value in that variable containing a mapping from the given key to the given value. In a manner analogous to lset, where multiple keys are present, they do indexing into nested dictionaries.

dict size dictionaryValue

Return the number of key/value mappings in the given dictionary value.

dict unset dictionaryVariable key ?key ...?

This operation (the companion to dict set) takes the name of a variable containing a dictionary value and places an updated dictionary value in that variable that does not contain a mapping for the given key. Where multiple keys are present, this describes a path through nested dictionaries to the mapping to remove. At least one key must be specified, but the last key on the key-path need not exist. All other components on the path must exist.

dict values dictionaryValue ?globPattern?

Return a list of all values in the given dictionary value. If a pattern is supplied, only those values that match it (according to the rules of string match) will be returned. The returned values will be in an arbitrary implementation-specific order, though where no pattern is supplied the i'th key returned by dict keys will be the key for the i'th value returned by dict values applied to the same dictionary value.

KEYWORDS

dictionary, create, update, lookup, iterate, filter

Copyright © 2003 Donal K. Fellows
Copyright © 1995-1997 Roger E. Critchlow Jr.

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