From 68d53c01b0b8e9a007a6a30158c19e34b2d2a34e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Wed, 18 May 2016 15:53:35 +0200 Subject: Update STDLIB documentation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Language cleaned up by the technical writers xsipewe and tmanevik from Combitech. Proofreading and corrections by Björn Gustavsson and Hans Bolinder. --- lib/stdlib/doc/src/proplists.xml | 280 ++++++++++++++++++++++++--------------- 1 file changed, 171 insertions(+), 109 deletions(-) (limited to 'lib/stdlib/doc/src/proplists.xml') diff --git a/lib/stdlib/doc/src/proplists.xml b/lib/stdlib/doc/src/proplists.xml index 832df9556a..fe6b8cc3bf 100644 --- a/lib/stdlib/doc/src/proplists.xml +++ b/lib/stdlib/doc/src/proplists.xml @@ -30,51 +30,66 @@ 2002-09-28 A - proplists.sgml + proplists.xml proplists - Support functions for property lists + Support functions for property lists.

Property lists are ordinary lists containing entries in the form of either tuples, whose first elements are keys used for lookup and - insertion, or atoms, which work as shorthand for tuples {Atom, true}. (Other terms are allowed in the lists, but are ignored - by this module.) If there is more than one entry in a list for a + insertion, or atoms, which work as shorthand for tuples + {Atom, true}. (Other terms are allowed in the lists, but are + ignored by this module.) If there is more than one entry in a list for a certain key, the first occurrence normally overrides any later (irrespective of the arity of the tuples).

+

Property lists are useful for representing inherited properties, - such as options passed to a function where a user may specify options + such as options passed to a function where a user can specify options overriding the default settings, object properties, annotations, - etc.

-

Two keys are considered equal if they match (=:=). In other - words, numbers are compared literally rather than by value, so that, - for instance, 1 and 1.0 are different keys.

+ and so on.

+ +

Two keys are considered equal if they match (=:=). That is, + numbers are compared literally rather than by value, so that, + for example, 1 and 1.0 are different keys.

 + + -

Similar to get_all_values/2, but each value is - wrapped in a list unless it is already itself a list, and the - resulting list of lists is concatenated. This is often useful for - "incremental" options; e.g., append_values(a, [{a, [1,2]}, {b, 0}, {a, 3}, {c, -1}, {a, [4]}]) will return the list - [1,2,3,4].

+

Similar to + get_all_values/2, + but each value is wrapped in a list unless it is already itself a + list. The resulting list of lists is concatenated. This is often + useful for "incremental" options.

+

Example:

+ +append_values(a, [{a, [1,2]}, {b, 0}, {a, 3}, {c, -1}, {a, [4]}]) +

returns:

+ +[1,2,3,4] +

Minimizes the representation of all entries in the list. This is equivalent to .

-

See also: property/1, unfold/1.

+

See also + property/1, + unfold/1.

 + @@ -83,96 +98,111 @@ List.

 +

Expands particular properties to corresponding sets of - properties (or other terms). For each pair {Property, Expansion} in Expansions, if E is - the first entry in ListIn with the same key as - Property, and E and Property - have equivalent normal forms, then E is replaced with - the terms in Expansion, and any following entries with - the same key are deleted from ListIn.

-

For example, the following expressions all return [fie, bar, baz, fum]:

+ properties (or other terms). For each pair {Property, + Expansion} in Expansions: if + E is the first entry in ListIn with the + same key as Property, and E and + Property have equivalent normal forms, then + E is replaced with the terms in Expansion, + and any following entries with the same key are deleted from + ListIn.

+

For example, the following expressions all return + [fie, bar, baz, fum]:

- expand([{foo, [bar, baz]}], - [fie, foo, fum]) - expand([{{foo, true}, [bar, baz]}], - [fie, foo, fum]) - expand([{{foo, false}, [bar, baz]}], - [fie, {foo, false}, fum]) -

However, no expansion is done in the following call:

+expand([{foo, [bar, baz]}], [fie, foo, fum]) +expand([{{foo, true}, [bar, baz]}], [fie, foo, fum]) +expand([{{foo, false}, [bar, baz]}], [fie, {foo, false}, fum]) +

However, no expansion is done in the following call + because {foo, false} shadows foo:

- expand([{{foo, true}, [bar, baz]}], - [{foo, false}, fie, foo, fum]) -

because {foo, false} shadows foo.

-

Note that if the original property term is to be preserved in the +expand([{{foo, true}, [bar, baz]}], [{foo, false}, fie, foo, fum]) +

Notice that if the original property term is to be preserved in the result when expanded, it must be included in the expansion list. The inserted terms are not expanded recursively. If - Expansions contains more than one property with the same - key, only the first occurrence is used.

-

See also: normalize/2.

+ Expansions contains more than one property with + the same key, only the first occurrence is used.

+

See also + normalize/2.

 + -

Similar to get_value/2, but returns the list of - values for all entries {Key, Value} in - List. If no such entry exists, the result is the empty - list.

-

See also: get_value/2.

+

Similar to + get_value/2, + but returns the list of values for all entries + {Key, Value} in List. If no such entry + exists, the result is the empty list.

 +

Returns the value of a boolean key/value option. If - lookup(Key, List) would yield {Key, true}, - this function returns true; otherwise false - is returned.

-

See also: get_value/2, lookup/2.

+ lookup(Key, List) would yield + {Key, true}, this function returns true, + otherwise false.

+

See also + get_value/2, + lookup/2.

 + -

Returns an unordered list of the keys used in List, - not containing duplicates.

+

Returns an unordered list of the keys used in + List, not containing duplicates.

 + -

Equivalent to get_value(Key, List, undefined).

+

Equivalent to + get_value(Key, List, undefined).

 +

Returns the value of a simple key/value property in - List. If lookup(Key, List) would yield - {Key, Value}, this function returns the corresponding - Value, otherwise Default is returned.

-

See also: get_all_values/2, get_bool/2, - get_value/2, lookup/2.

+ List. If lookup(Key, + List) would yield {Key, Value}, + this function returns the corresponding Value, otherwise + Default.

+

See also + get_all_values/2, + get_bool/2, + get_value/2, + lookup/2.

 +

Returns true if List contains at least one entry associated with Key, otherwise - false is returned.

+ false.

 + @@ -181,128 +211,160 @@ List, if one exists, otherwise returns none. For an atom A in the list, the tuple {A, true} is the entry associated with A.

-

See also: get_bool/2, get_value/2, - lookup_all/2.

+

See also + get_bool/2, + get_value/2, + lookup_all/2.

 + -

Returns the list of all entries associated with Key - in List. If no such entry exists, the result is the - empty list.

-

See also: lookup/2.

+

Returns the list of all entries associated with + Key in List. If no such entry + exists, the result is the empty list.

+

See also + lookup/2.

 +

Passes ListIn through a sequence of substitution/expansion stages. For an aliases operation, - the function substitute_aliases/2 is applied using the - given list of aliases; for a negations operation, - substitute_negations/2 is applied using the given - negation list; for an expand operation, the function - expand/2 is applied using the given list of expansions. - The final result is automatically compacted (cf. - compact/1).

+ function + substitute_aliases/2 is applied using the + specified list of aliases:

+ + +

For a negations operation, substitute_negations/2 + is applied using the specified negation list.

+ + +

For an expand operation, function + expand/2 + is applied using the specified list of expansions.

+ + +

The final result is automatically compacted (compare + compact/1).

Typically you want to substitute negations first, then aliases, then perform one or more expansions (sometimes you want to pre-expand particular entries before doing the main expansion). You might want to substitute negations and/or aliases repeatedly, to allow such forms in the right-hand side of aliases and expansion lists.

-

See also: compact/1, expand/2, - substitute_aliases/2, substitute_negations/2.

+

See also + substitute_negations/2.

 +

Creates a normal form (minimal) representation of a property. If - PropertyIn is {Key, true} where - Key is an atom, this returns Key, otherwise - the whole term PropertyIn is returned.

-

See also: property/2.

+ PropertyIn is {Key, true}, where + Key is an atom, Key is returned, otherwise + the whole term PropertyIn is returned.

+

See also + property/2.

 + -

Creates a normal form (minimal) representation of a simple - key/value property. Returns Key if Value is - true and Key is an atom, otherwise a tuple - {Key, Value} is returned.

-

See also: property/1.

+

Creates a normal form (minimal) representation of a simple key/value + property. Returns Key if Value + is true and Key is an atom, otherwise a + tuple {Key, Value} is returned.

+

See also + property/1.

 +

Partitions List into a list of sublists and a - remainder. Lists contains one sublist for each key in - Keys, in the corresponding order. The relative order of - the elements in each sublist is preserved from the original - List. Rest contains the elements in - List that are not associated with any of the given keys, + remainder. Lists contains one sublist for each key + in Keys, in the corresponding order. The relative + order of the elements in each sublist is preserved from the original + List. Rest contains the + elements in List that are not associated with any + of the specified keys, also with their original relative order preserved.

-

Example: - split([{c, 2}, {e, 1}, a, {c, 3, 4}, d, {b, 5}, b], [a, b, c])

-

returns

-

{[[a], [{b, 5}, b],[{c, 2}, {c, 3, 4}]], [{e, 1}, d]}

+

Example:

+ +split([{c, 2}, {e, 1}, a, {c, 3, 4}, d, {b, 5}, b], [a, b, c]) +

returns:

+ +{[[a], [{b, 5}, b],[{c, 2}, {c, 3, 4}]], [{e, 1}, d]} +

Substitutes keys of properties. For each entry in - ListIn, if it is associated with some key K1 - such that {K1, K2} occurs in Aliases, the + ListIn, if it is associated with some key + K1 such that {K1, K2} occurs in + Aliases, the key of the entry is changed to K2. If the same K1 occurs more than once in Aliases, only the first occurrence is used.

-

Example: substitute_aliases([{color, colour}], L) - will replace all tuples {color, ...} in L +

For example, substitute_aliases([{color, colour}], L) + replaces all tuples {color, ...} in L with {colour, ...}, and all atoms color with colour.

-

See also: normalize/2, substitute_negations/2.

+

See also + normalize/2, + + substitute_negations/2.

 +

Substitutes keys of boolean-valued properties and simultaneously negates their values. For each entry in - ListIn, if it is associated with some key K1 - such that {K1, K2} occurs in Negations, then - if the entry was {K1, true} it will be replaced with - {K2, false}, otherwise it will be replaced with - {K2, true}, thus changing the name of the option and - simultaneously negating the value given by - get_bool(ListIn). If the same K1 occurs more - than once in Negations, only the first occurrence is - used.

-

Example: substitute_negations([{no_foo, foo}], L) - will replace any atom no_foo or tuple + ListIn, if it is associated with some key + K1 such that {K1, K2} occurs in + Negations: if the entry was + {K1, true}, it is replaced with {K2, false}, otherwise + with {K2, true}, thus changing the name of the option and + simultaneously negating the value specified by + + get_bool(Key, ListIn. + If the same K1 occurs more than once in + Negations, only the first occurrence is used.

+

For example, substitute_negations([{no_foo, foo}], L) + replaces any atom no_foo or tuple {no_foo, true} in L with {foo, false}, - and any other tuple {no_foo, ...} with - {foo, true}.

-

See also: get_bool/2, normalize/2, - substitute_aliases/2.

+ and any other tuple {no_foo, ...} with {foo, true}.

+

See also + get_bool/2, + normalize/2, + + substitute_aliases/2.

 + -

Unfolds all occurrences of atoms in ListIn to tuples - {Atom, true}.

+

Unfolds all occurrences of atoms in ListIn to + tuples {Atom, true}.

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