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<TITLE>Built in functions</TITLE>
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<H2>6 Built in functions</H2>
<A NAME="6.1"><!-- Empty --></A>
<H3>6.1 Some notes about BIFs</H3>
<P>
<P>
<DL>
<DT>
<STRONG>list_to_atom/1</STRONG>
</DT>
<DD>
Since atoms are not garbage collected it is not a good
idea to create atoms dynamically in a system that will run
continously. Sooner or later the limit 1048576 for number of
atoms will be reached with a emulator crash as result. In
addition to the bad memory consumption characteristics the
function is also quite expensive to execute.
</DD>
<DT>
<STRONG>length/1</STRONG>
</DT>
<DD>
is an operation on lists and each time the
length is tested the entire list must be traversed. Since
length is implemented in C it is quite efficient anyway but it
still has linear characteristics. The size/1 function which
can be applied on tuples and binaries is for example much more
efficient since it only reads a size field in the internal
data structure.
</DD>
<DT>
<STRONG>setelement/3</STRONG>
</DT>
<DD>
Compared with element/2 that is very efficient and independent of the tuple size
setelement/3 is an expensive operation for large tuples
(>50 elements) since it implies that all fields must be copied
to a new tuple. Therefore it is not recommended to use setelement in recursions
involving large tuples.
</DD>
<DT>
<STRONG>split_binary/2</STRONG>
</DT>
<DD>
Depending on the situation it is in most cases more
efficient to split a binary through matching instead of calling
the split_binary/2 function.<BR>
<STRONG>DO</STRONG><BR>
<PRE>
<<Bin1:Num/binary,Bin2/binary>> = Bin,
</PRE>
<STRONG>DON'T</STRONG><BR>
<PRE>
{Bin1,Bin2} = split_binary(Bin,Num),
</PRE>
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