Vimscript dictionary

The last Vimscript type we're talking about will be a dictionary. The Vimscript dictionary is similar to the dict in Python, the hash in Ruby, and the object in Javascript.

The dictionary is created with braces. T he value is heterogeneic, but the key is cast into a string. It's as simple as that, didn't you?

To execute this command:

:echo {'a': 1, 100: 'foo'}

Vim {'a':1,'100':'foo'} which means that Vimscript does cast the key to a string while keeping the value unchanged.

Vimscript avoids the stupidity of the Javascript standard, allowing you to leave a comma behind the last element of the dictionary. I n Javascript standards, the last element cannot be followed by a comma. B ut in Firefox, it's allowed to leave that comma, but that's Firefox's problem. Do the following command:

:echo {'a': 1, 100: 'foo',}

Vim again shows {'a':1,'100':'foo'} You should always leave an extra comma in the dictionary, especially if the dictionary definition spans multiple lines, so adding new items is not easy to make mistakes.

Index

The syntax for finding a value in a dictionary is the same as in most languages. To execute this command:

:echo {'a': 1, 100: 'foo',}['a']

Vim shows 1 . Try using an index that is not a string:

:echo {'a': 1, 100: 'foo',}[100]

Vim makes sense to cast the index into a string before looking, because the key can only be a string.

Vimscript also supports Javascript-style "dot" lookups when the keys consist only of letters, numbers, and/or underscores. Try the following command:

:echo {'a': 1, 100: 'foo',}.a
:echo {'a': 1, 100: 'foo',}.100

In both cases, Vim shows the correct elements. The way you use an index dictionary depends on your own preferences.

Assignments and additions

Assigning items to a dictionary as if they were variables makes it easy to add new items to the dictionary.

:let foo = {'a': 1}
:let foo.a = 100
:let foo.b = 200
:echo foo

Vim {'a': 100, 'b': 200} . The assignment is the same as adding a new item.

Remove the item

There are two ways to remove items from a dictionary. Execute the following command:

:let test = remove(foo, 'a')
:unlet foo.b
:echo foo
:echo test

Vim {} and 100 . remove function removes the item for a given key in a given dictionary and returns the value that was removed. unlet command also removes items from the dictionary, but does not return a value.

You cannot remove items that do not exist in the dictionary. Try this command:

:unlet foo["asdf"]

Vim throws an error.

The choice remove or unlet largely on personal preference. I f I have to say, I recommend remove is more unlet remove do anything unlet which in turn does not hold true. So choose remove can be fresh, eat all over the day.

Dictionary function

Like a list, Vim has many built-in dictionary functions. Execute the following command:

:echom get({'a': 100}, 'a', 'default')
:echom get({'a': 100}, 'b', 'default')

Vim displays 100 default like the list version of get function.

You can also check whether a given key is in a given dictionary. To execute this command:

:echom has_key({'a': 100}, 'a')
:echom has_key({'a': 100}, 'b')

Vim shows 1 and 0 Don't forget that Vimscript 0 as a fake and other numbers as true.

You can execute this command by using items to get the corresponding key value pair from a dictionary:

:echo items({'a': 100, 'b': 200})

Vim will display such nested lists as [['a',100],['b',200]] and so on. So far, the Vimscript dictionary is not necessarily ordered, so don't expect items to return in an orderly manner!

You can use keys return all the keys in the dictionary and values return all the values. They work as well as they are - you can check it out.

Practice

Read :help Dictionary A fter reading it. Note capital D

Read :help get() .

Read :help has_key() .

Read :help items() .

Read :help keys() .

Read :help values() .