Records

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== Defining Records == == Defining Records ==
 +
 +=== Without Defaults ===
 +
 +Defining a record in code looks like this:
<code> <code>
-record( recordname, { element1, element2, element3 } ). -record( recordname, { element1, element2, element3 } ).
</code> </code>
 +
 +Defining one in the interpreter looks like this:
 +
 +<code>
 +rd(recordname, {element1, element2, element3}).
 +</code>
 +
 +=== With Defaults ===
== Creating a Record == == Creating a Record ==
 +
 +Defining a record in code looks like this:
<code> <code>
-R = #recordname{ element1 = "One", element2 = 2, element3 = three }.+-record( recordname, { element1 = "One", element2 = 2, element3 = three } ).
 +</code>
 + 
 +Defining one in the interpreter (what I did to create these examples) looks like this:
 + 
 +<code>
 +rd(recordname, {element1 = "One", element2 = 2, element3 = three }).
</code> </code>
Line 15: Line 35:
<code> <code>
elementTwoTimesEight( #recordname{ element2 = T } ) -> T * 8. elementTwoTimesEight( #recordname{ element2 = T } ) -> T * 8.
 +</code>
 +
 +== Modifying a Record ==
 +
 +<code>
 +2> R1 = #recordname{}. % Uses the defaults.
 +#recordname{element1 = "One",element2 = 2,element3 = three}
 +3> R2 = R1#recordname{ element1 = "Two" }. % Only modify one part of the record.
 +#recordname{element1 = "Two",element2 = 2,element3 = three}
</code> </code>

Revision as of 11:43, 15 July 2007

Contents

Defining Records

Without Defaults

Defining a record in code looks like this: 

-record( recordname, { element1, element2, element3 } ).

Defining one in the interpreter looks like this: 

rd(recordname, {element1, element2, element3}).

With Defaults

Creating a Record

Defining a record in code looks like this: 

-record( recordname, { element1 = "One", element2 = 2, element3 = three } ).

Defining one in the interpreter (what I did to create these examples) looks like this: 

rd(recordname, {element1 = "One", element2 = 2, element3  = three }).

Matching a Record 

elementTwoTimesEight( #recordname{ element2 = T } ) -> T * 8.

Modifying a Record 

2> R1 = #recordname{}.  % Uses the defaults. 
#recordname{element1 = "One",element2 = 2,element3 = three}
3> R2 = R1#recordname{ element1 = "Two" }.  % Only modify one part of the record.
#recordname{element1 = "Two",element2 = 2,element3 = three}

More Information

More information at http://erlang.org/doc/getting_started/records_macros.html#5.3.

Retrieved from "http://www.trapexit.org/Records"
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