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Diffstat (limited to 'lib/stdlib/doc')
| -rw-r--r-- | lib/stdlib/doc/src/notes.xml | 261 |
1 files changed, 261 insertions, 0 deletions
diff --git a/lib/stdlib/doc/src/notes.xml b/lib/stdlib/doc/src/notes.xml index 87f5335723..76d49e37c2 100644 --- a/lib/stdlib/doc/src/notes.xml +++ b/lib/stdlib/doc/src/notes.xml @@ -31,6 +31,267 @@ </header> <p>This document describes the changes made to the STDLIB application.</p> +<section><title>STDLIB 3.0</title> + + <section><title>Fixed Bugs and Malfunctions</title> + <list> + <item> + <p> Fix a race bug affecting <c>dets:open_file/2</c>. + </p> + <p> + Own Id: OTP-13260 Aux Id: seq13002 </p> + </item> + <item> + <p>Don't search for non-existing Map keys twice</p> + <p>For <c>maps:get/2,3</c> and <c>maps:find/2</c>, + searching for an immediate key, e.g. an atom, in a small + map, the search was performed twice if the key did not + exist.</p> + <p> + Own Id: OTP-13459</p> + </item> + <item> + <p> + Avoid stray corner-case math errors on Solaris, e.g. an + error is thrown on undeflows in exp() and pow() when it + shouldn't be.</p> + <p> + Own Id: OTP-13531</p> + </item> + <item> + <p>Fix linting of map key variables</p> + <p>Map keys cannot be unbound and then used in parallel + matching.</p> + <p>Example: <c> #{ K := V } = #{ k := K } = M.</c> This + is illegal if <c>'K'</c> is not bound.</p> + <p> + Own Id: OTP-13534 Aux Id: ERL-135 </p> + </item> + </list> + </section> + + + <section><title>Improvements and New Features</title> + <list> + <item> + <p>The types of The Abstract Format in the + <c>erl_parse</c> module have been refined. </p> + <p> + Own Id: OTP-10292</p> + </item> + <item> + <p> Undocumented syntax for function specifications, + <c>-spec F/A :: Domain -> Range</c>, has been removed + (without deprecation). </p> <p> Using the + <c>is_subtype(V, T)</c> syntax for constraints (in + function specifications) is no longer documented, and the + newer syntax <c>V :: T</c> should be used instead. The + Erlang Parser still recognizes the <c>is_subtype</c> + syntax, and will continue to do so for some time. </p> + <p> + *** POTENTIAL INCOMPATIBILITY ***</p> + <p> + Own Id: OTP-11879</p> + </item> + <item> + <p>The '<c>random</c>' module has been deprecated. Use + the '<c>rand</c>' module instead.</p> + <p> + Own Id: OTP-12502 Aux Id: OTP-12501 </p> + </item> + <item> + <p>Background: In record fields with a type declaration + but without an initializer, the Erlang parser inserted + automatically the singleton type <c>'undefined'</c> to + the list of declared types, if that value was not present + there. That is, the record declaration:</p> + <p> + -record(rec, {f1 :: float(), f2 = 42 :: integer(), f3 :: + some_mod:some_typ()}).</p> + <p>was translated by the parser to:</p> + <p> + -record(rec, {f1 :: float() | 'undefined', f2 = 42 :: + integer(), f3 :: some_mod:some_typ() | 'undefined'}).</p> + <p>The rationale for this was that creation of a "dummy" + <c>#rec{}</c> record should not result in a warning from + dialyzer that, for example, the implicit initialization + of the <c>#rec.f1</c> field violates its type + declaration.</p> + <p>Problems: This seemingly innocent action has some + unforeseen consequences.</p> + <p>For starters, there is no way for programmers to + declare that e.g. only floats make sense for the + <c>f1</c> field of <c>#rec{}</c> records when there is no + "obvious" default initializer for this field. (This also + affects tools like PropEr that use these declarations + produced by the Erlang parser to generate random + instances of records for testing purposes.)</p> + <p>It also means that dialyzer does not warn if e.g. an + <c>is_atom/1</c> test or something more exotic like an + <c>atom_to_list/1</c> call is performed on the value of + the <c>f1</c> field.</p> + <p>Similarly, there is no way to extend dialyzer to warn + if it finds record constructions where <c>f1</c> is not + initialized to some float.</p> + <p>Last but not least, it is semantically problematic + when the type of the field is an opaque type: creating a + union of an opaque and a structured type is very + problematic for analysis because it fundamentally breaks + the opacity of the term at that point.</p> + <p>Change: To solve these problems the parser will not + automatically insert the <c>'undefined'</c> value + anymore; instead the user has the option to choose the + places where this value makes sense (for the field) and + where it does not and insert the <c>| 'undefined'</c> + there manually.</p> + <p>Consequences of this change: This change means that + dialyzer will issue a warning for all places where + records with uninitialized fields are created and those + fields have a declared type that is incompatible with + <c>'undefined'</c> (e.g. <c>float()</c>). This warning + can be suppressed easily by adding <c>| 'undefined'</c> + to the type of this field. This also adds documentation + that the user really intends to create records where this + field is uninitialized.</p> + <p> + *** POTENTIAL INCOMPATIBILITY ***</p> + <p> + Own Id: OTP-12719</p> + </item> + <item> + <p> Remove deprecated functions in the modules + <c>erl_scan</c> and <c>erl_parse</c>. </p> + <p> + Own Id: OTP-12861</p> + </item> + <item> + <p>The pre-processor can now expand the ?FUNCTION_NAME + and ?FUNCTION_ARITY macros.</p> + <p> + Own Id: OTP-13059</p> + </item> + <item> + <p> A new behaviour <c>gen_statem</c> has been + implemented. It has been thoroughly reviewed, is stable + enough to be used by at least two heavy OTP applications, + and is here to stay. But depending on user feedback, we + do not expect but might find it necessary to make minor + not backwards compatible changes into OTP-20.0, so its + state can be designated as "not quite experimental"... + </p> <p> The <c>gen_statem</c> behaviour is intended to + replace <c>gen_fsm</c> for new code. It has the same + features and add some really useful: </p> <list + type="bulleted"> <item>State code is gathered</item> + <item>The state can be any term</item> <item>Events can + be postponed</item> <item>Events can be self + generated</item> <item>A reply can be sent from a later + state</item> <item>There can be multiple sys traceable + replies</item> </list> <p> The callback model(s) for + <c>gen_statem</c> differs from the one for + <c>gen_fsm</c>, but it is still fairly easy to rewrite + from <c>gen_fsm</c> to <c>gen_statem</c>. </p> + <p> + Own Id: OTP-13065 Aux Id: PR-960 </p> + </item> + <item> + <p> + Optimize binary:split/2 and binary:split/3 with native + BIF implementation.</p> + <p> + Own Id: OTP-13082</p> + </item> + <item> + <p>Background: The types of record fields have since R12B + been put in a separate form by <c>epp:parse_file()</c>, + leaving the record declaration form untyped. The separate + form, however, does not follow the syntax of type + declarations, and parse transforms inspecting + <c>-type()</c> attributes need to know about the special + syntax. Since the compiler stores the return value of + <c>epp:parse_file()</c> as debug information in the + abstract code chunk (<c>"Abst"</c> or + <c>abstract_code</c>), tools too need to know about the + special syntax, if they inspect <c>-type()</c> attributes + in abstract code.</p> + <p>Change: No separate type form is created by + <c>epp:parse_file()</c>, but the type information is kept + in the record fields. This means that all parse + transforms and all tools inspecting <c>-record()</c> + declarations need to recognize <c>{typed_record_field, + Field, Type}</c>.</p> + <p> + *** POTENTIAL INCOMPATIBILITY ***</p> + <p> + Own Id: OTP-13148</p> + </item> + <item> + <p> + Unsized fields of the type <c>bytes</c> in binary + generators are now forbidden. (The other ways of writing + unsized fields, such as <c>binary</c>, are already + forbidden.)</p> + <p> + Own Id: OTP-13152</p> + </item> + <item> + <p> The type <c>map()</c> is built-in, and cannot be + redefined. </p> + <p> + Own Id: OTP-13153</p> + </item> + <item> + <p> Let <c>dets:open_file()</c> exit with a <c>badarg</c> + message if given a raw file name (a binary). </p> + <p> + Own Id: OTP-13229 Aux Id: ERL-55 </p> + </item> + <item> + <p> Add <c>filename:basedir/2,3</c></p> <p>basedir + returns suitable path(s) for 'user_cache', 'user_config', + 'user_data', 'user_log', 'site_config' and 'site_data'. + On linux and linux like systems the paths will respect + the XDG environment variables.</p> + <p> + Own Id: OTP-13392</p> + </item> + <item> + <p>There are new preprocessor directives + <c>-error(Term)</c> and <c>-warning(Term)</c> to cause a + compilation error or a compilation warning, + respectively.</p> + <p> + Own Id: OTP-13476</p> + </item> + <item> + <p> + Optimize <c>'++'</c> operator and <c>lists:append/2</c> + by using a single pass to build a new list while checking + for properness.</p> + <p> + Own Id: OTP-13487</p> + </item> + <item> + <p> + Add <c>maps:update_with/3,4</c> and <c>maps:take/2</c></p> + <p> + Own Id: OTP-13522 Aux Id: PR-1025 </p> + </item> + <item> + <p><c>lists:join/2</c> has been added. Similar to + <c>string:join/2</c> but works with arbitrary lists.</p> + <p> + Own Id: OTP-13523</p> + </item> + <item> + <p>Obfuscate asserts to make Dialyzer shut up.</p> + <p> + Own Id: OTP-13524 Aux Id: PR-1002 </p> + </item> + </list> + </section> + +</section> + <section><title>STDLIB 2.8</title> <section><title>Fixed Bugs and Malfunctions</title> |