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SYNOPSIS
mixed * filter(mixed *arg, string fun, string|object ob
, mixed extra...)
mixed * filter(mixed *arg, closure cl, mixed extra...)
mixed * filter(mixed *arg, mapping map, mixed extra...)
string filter(string arg, string fun, string|object ob
, mixed extra...)
string filter(string arg, closure cl, mixed extra...)
string filter(string arg, mapping map, mixed extra...)
mapping filter(mapping arg, string func, string|object ob
, mixed extra...)
mapping filter(mapping arg, closure cl, mixed extra...)
DESCRIPTION
Call the function <ob>-><func>() resp. the closure <cl> for
every element of the array, or mapping <arg>, and return a
result made from those elements for which the function call
returns TRUE. The <extra> arguments are passed as additional
parameters to the function calls and must not be references of
array of mapping elements (like &(i[1]) ).
If <ob> is omitted, or neither a string nor an object, it
defaults to this_object().
If <arg> is an array or struct, the function will be called with
each of the array/struct values as first parameter, followed by the
<extra> arguments. If the result from the function call is true,
the array element in question is included into the efun result.
If the efun is used with a mapping <map> instead of a function,
every array element which is key in <map> is included into the
result.
If <arg> is a mapping, the function will be called with
each of the mapping keys as first, and (if existing) the
associated values as second parameter, followed by the <extra>
arguments. If the result is true, the mapping element in question
is included into the result.
Depending on the width of the mapping <arg>, the function
call takes one of three forms:
widthof(arg) == 0: ob->func(key, 0, extra...)
== 1: ob->func(key, arg[key], extra...)
> 1: ob->func( key
, ({ arg[key,0] ...arg[key,width-1] })
, extra...)
The advantage of this approach is that the two types of
multi-dimensional mappings (mappings with multiple values
per key, and mappings of arrays) can be treated in the same way.
Historical Note: filter() used with arrays behaves like
filter_array(), but used with mappings is a generalisation of
filter_indices().
HISTORY
Introduced in LDMud 3.2.6, obsoletes filter_array().
LDMud 3.3.439 added filtering of strings.
SEE ALSO
filter(E), filter_indices(E), map(E), walk_mapping(E), member(E),
m_contains(E)