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Null object (view source)

Revision as of 11:59, 26 September 2012

8 bytes added ,  11 years ago
m
[Erlang] Format cleanup, improve wording.
m ([Erlang] Format code clearly.)
m ([Erlang] Format cleanup, improve wording.)
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=={{header|Erlang}}==
 
Erlang does not have an undefinednull valueobject. As an alternative, many applications tend to pick a convention for returnreturning valuesan empty condition and use that.
 
Example alternatives:
# Something like <pre>{ok, 3} % normal case</pre> or <pre>{err, no_more} % error case</pre> on error.
# Don't ever allow an undefined return value, and throw an exception instead.
# Return an atom:
## <pre>'''undefined</pre>'''*
## <pre>'''undef</pre>'''
## <pre>'''null</pre>'''
## <pre>'''nil</pre>'''
## <pre>'''none</pre>'''
 
<pre>'''undefined</pre>''' is often used by records as an initial value and the stdlib module.
 
Atoms are erlang's user-defined constants that always evaluates to is itself. It is also equal to no other value else but itself.
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