Erlang Programming/Records

From Wikibooks, open books for an open world
< Erlang Programming
Jump to: navigation, search

Records in Erlang are syntactic sugar for tagged tuples. The functionality is provided by the preprocessor, not the compiler, so there are some interesting restrictions on how you use them and their support functions.


Defining Records[edit]

-record(myrecord, {first_element, second_element}).

The code above defines a record called myrecord with two elements: "first_element" and "second_element". From now on we can use the record syntax #myrecord{}.

Equivalent to Tuples[edit]

Records are syntactic sugar for tuples.

#myrecord{first_element=foo, second_element=bar} =:= {myrecord, foo, bar}.
#myrecord{} =:= {myrecord, undefined, undefined}.

The record we defined with two fields is equivalent to a tuple with a tag (the name of the record) and as many elements as the record has fields -- two, in our case.