Pairs¶

Pairs are a type of entry. In OLDL, you can spot them by the colon.

Input	Output
`foo:bar`	`[P("foo", "bar")]`

There should not be any space around the colon. If so, it should be considered as a text entry.

Input	Output
`foo :bar`	`[T("foo :bar")]`
`foo: bar`	`[T("foo: bar")]`
`foo : bar`	`[T("foo : bar")]`

Keys and Values with Multiple Words¶

The key and value in a pair might include a space, but then the key or value should be enclosed in single or double quotes.

Input	Output
`foo:"bar baz"`	`[P("foo", "bar baz")]`
`foo:'bar baz'`	`[P("foo", "bar baz")]`
`"foo bar":baz`	`[P("foo bar", "baz")]`
`'foo bar':baz`	`[P("foo bar", "baz")]`

Warning (For Developers)

While this is an option, this is usually not a good idea. It breaks the readability and makes it harder to comprehend. So, avoid it as much as possible.

The Type of Key and Value¶

The type of key and (especially) value should always be string. That is because it is the developer's responsibility to handle the type.

There are many possible types out there. While the primitive ones are integers, floats, booleans or whatnot, the developer might want to have, for example, a valid datetime, or a range for prices. The possibilities are limitless. So, it's better to KISS.

While the implementors should always provide their implementations to always return a string for key and value in a pair, they might want to choose to expand it with extensions. The core, however, should obey this principle.

Arrays (Especially for Developers)¶

As mentioned The Type of Key and Value, there is no other type than string. However, the developer might want to have an array. For example, filtering the movies by multiple genres. Two possible approaches come to mind.

Approach	Input	Output	Description	Pros	Cons
One key with comma-separated values	`genres:action,horror`	`[P("genres", "action,horror")]`	Use a split method on value	Easier to write	User might provide comma+space separated values, which breaks the parser
Multiple keys with different values	`genre:action genre:horror`	`[P("genre", "action"), P("genre", "horror")]`	Add values to a list each time a key with same name occurs	Easier to comprehend	Many keystrokes Takes longer to write

Pick your poison.