path: root/system/doc/top/incompatible.xml

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<!DOCTYPE chapter SYSTEM "chapter.dtd">

<chapter>
  <header>
    <copyright>
      <year>2006</year><year>2009</year>
      <holder>Ericsson AB. All Rights Reserved.</holder>
    </copyright>
    <legalnotice>
      The contents of this file are subject to the Erlang Public License,
      Version 1.1, (the "License"); you may not use this file except in
      compliance with the License. You should have received a copy of the
      Erlang Public License along with this software. If not, it can be
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      basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
      the License for the specific language governing rights and limitations
      under the License.
    
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    <title>Potential Incompatibilities</title>
    <prepared></prepared>
    <docno></docno>
    <date></date>
    <rev></rev>
    <file>incompatible.xml</file>
  </header>
  <p>This document contains a list of potential incompatibilities
    between Erlang 5.7/OTP R12A and Erl 5.6.5/OTP R12B-5,
    and is an extract from the release notes for the respective applications.</p>

  <section>
    <title>compiler</title>
    <list type="bulleted">
        <item>
          <p>
	    The undocumented, unsupported, and deprecated guard BIF
	    <c>is_constant/1</c> has been removed.</p>
          <p>
	    *** INCOMPATIBILITY with R12B ***</p>
          <p>
	    Own Id: OTP-7673</p>
        </item>
        <item>
	    <p>The short-circuit operators <c>andalso</c> and
	    <c>orelse</c> no longer guarantees that their second
	    argument is either <c>true</c> or <c>false</c>. As a
	    consequence, <c>andalso</c>/<c>orelse</c> are now
	    tail-recursive.</p>
          <p>
	    *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
	    Own Id: OTP-7748</p>
        </item>
        <item>
	    <p>The compiler will refuse to a compile file where the
	    module name in the file differs from the output file
	    name.</p>
	    <p>When compiling using <c>erlc</c>, the current working
	    directory will no be included in the code path (unless
	    explicitly added using "-pa .").</p>
          <p>
	    *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
	    Own Id: OTP-7793</p>
        </item>
        <item>
	    <p>If a module contains an exported function with the
	    same name as an auto-imported BIF (such as
	    <c>length/1</c>), any calls to the BIF must have an
	    explicit <c>erlang:</c> prefix, or there will be a
	    compilation error (such calls would only generate a
	    warning in previous releases).</p>
	    <p>(The reason for the change is to avoid breaking code
	    in a future major release, R14 or R15, in which we plan
	    to make calls without a module prefix always call the
	    local function in the same module even if there is an
	    auto-imported BIF with the same name.)</p>
          <p>
	    *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
	    Own Id: OTP-7873</p>
        </item>
    </list>
  </section>

  <section>
    <title>Erts</title>
    <list type="bulleted">
        <item>
	    <p>Support for Unicode is implemented as described in
	    EEP10. Formatting and reading of unicode data both from
	    terminals and files is supported by the io and io_lib
	    modules. Files can be opened in modes with automatic
	    translation to and from different unicode formats. The
	    module 'unicode' contains functions for conversion
	    between external and internal unicode formats and the re
	    module has support for unicode data. There is also
	    language syntax for specifying string and character data
	    beyond the ISO-latin-1 range.</p>
	    <p>The interactive shell will support input and output of
	    unicode characters when the terminal and operating system
	    supports it.</p>
	    <p>Please see the EEP and the io/io_lib manual pages as
	    well as the stdlib users guide for details.</p>
	    <p><em>I/O-protocol incompatibilities:</em></p>
	    <p>The io_protocol between io_Server and client is
	    updated to handle protocol data in unicode formats. The
	    updated protocol is now documented. The specification
	    resides in the stdlib <em>users manual</em>, which is a
	    new part of the manual.</p>
	    <p><em>io module incompatibilities:</em></p>
	    <p>The io:put_chars, io:get_chars and io:get_line all
	    handle and return unicode data. In the case where
	    binaries can be provided (as to io:put_chars), they shall
	    be encoded in UTF-8. When binaries are returned (as by
	    io:get_line/get_chars when the io_server is set in
	    <em>binary mode</em>) the returned data is also
	    <em>always</em> encoded as UTF-8. The file module however
	    still returns byte-oriented data, why file:read can be
	    used instead of io:get_chars to read binary data in
	    ISO-latin-1.</p>
	    <p><em>io_lib module incompatibilities:</em></p>
	    <p>io_lib:format can, given new format directives (i.e
	    "~ts" and "~tc"), return lists containing integers larger
	    than 255. </p>
          <p>
	    *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
	    Own Id: OTP-7648 Aux Id: OTP-7580 OTP-7514 OTP-7494
	    OTP-7443 OTP-7181 EEP10 EEP11 </p>
        </item>
        <item>
          <p>
	    The undocumented, unsupported, and deprecated guard BIF
	    <c>is_constant/1</c> has been removed.</p>
          <p>
	    *** INCOMPATIBILITY with R12B ***</p>
          <p>
	    Own Id: OTP-7673</p>
        </item>
        <item>
	    <p>The short-circuit operators <c>andalso</c> and
	    <c>orelse</c> no longer guarantees that their second
	    argument is either <c>true</c> or <c>false</c>. As a
	    consequence, <c>andalso</c>/<c>orelse</c> are now
	    tail-recursive.</p>
          <p>
	    *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
	    Own Id: OTP-7748</p>
        </item>
        <item>
	    <p>The compiler will refuse to a compile file where the
	    module name in the file differs from the output file
	    name.</p>
	    <p>When compiling using <c>erlc</c>, the current working
	    directory will no be included in the code path (unless
	    explicitly added using "-pa .").</p>
          <p>
	    *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
	    Own Id: OTP-7793</p>
        </item>
        <item>
	    <p>The deprecated functions <c>erlang:fault/1</c>,
	    <c>erlang:fault/2</c>, and <c>file:rawopen/2</c> have
	    been removed.</p>
          <p>
	    *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
	    Own Id: OTP-7812</p>
        </item>
        <item>
	    <p>The escape sequences <c>\x</c> and <c>\{</c> have been
	    assigned new interpretations (they used to return the
	    ASCII code for <c>x</c> and <c>{</c> respectively). One
	    or more octal characters inside curly brackets after a
	    leading backslash is from now on an alternative to the
	    existing syntax <c>\NNN</c>, but can also be used for
	    codes greater than 255. In a similar fashion, one or more
	    hexadecimal characters can be put inside curly brackets
	    after a leading <c>\x</c>. Furthermore, the escape
	    sequences <c>\xH</c> and <c>\xHH</c>, where N is a
	    hexadecimal character, can be used for codes less than
	    256.</p>
	    <p>NOTE: These new escape sequences are still considered
	    experimental and may be changed in the R13B release.</p>
          <p>
	    *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
	    Own Id: OTP-7855</p>
        </item>
    </list>
  </section>

  <section>
    <title>Inets</title>
    <list type="bulleted">
     <item>
          <p>
            [httpc] - The inets http client will now use persistent
            connections without pipelining as default and if a
            pipeline timeout is set it will pipeline the requests on
            the persistent connections.</p>
          <p>
            *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
            Own Id: OTP-7463</p>
        </item>
    </list>
  </section>

    <section>
    <title>Jinterface</title>
      <list>
        <item>
          <p>
	    A number of fixes and improvements from the ErlIDE group;
	    Vlad Dumitrescu and Jakob Cederlund: JDK 1.5 is now a
	    minimal requirement for building Jinterface. New method:
	    OtpEpmd.lookupNames. OtpErlangList is now iterable.
	    Non-proper lists are now allowed - you have to test if a
	    list is proper or not. Non-proper lists can also be
	    created. New methods: isProper, getHead, getTail and
	    getNthTail. The get tail methods creates a sublist object
	    that re-uses the original list. OtpErlangPid is now
	    Comparable. Empty atoms can now be constructed, a missing
	    feature pointed out by Sebastien Boisgerault on
	    erlang-questions.</p>
          <p>
	    *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
	    Own Id: OTP-7832</p>
        </item>
      </list>
    </section>

  <section>
    <title>Kernel</title>
    <list type="bulleted">
        <item>
	    <p>The deprecated functions <c>erlang:fault/1</c>,
	    <c>erlang:fault/2</c>, and <c>file:rawopen/2</c> have
	    been removed.</p>
          <p>
	    *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
	    Own Id: OTP-7812</p>
        </item>
    </list>
  </section>

  <section>
    <title>SSH</title>
    <list type="bulleted">
        <item>
          <p>
            Ssh timeouts will now behave as expected i.e. defaults to
            infinity. Only the user of the ssh application can know of
            a reasonable timeout value for their application.</p>
          <p>
            *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
            Own Id: OTP-7807</p>
        </item>
        <item>
          <p>
            Added the message {ssh_channel_up, ChannelId,
            ConnectionManager} that shall be handled by the channel
            callback handle_msg/2. This makes the function
            handle_msg/2 a mandatory function for ssh channels
            implementations which it was not in ssh-1.1.</p>
          <p>
            *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
            Own Id: OTP-7828</p>
        </item>
    </list>
  </section>

  <section>
    <title>STDLIB</title>
    <list type="bulleted">
        <item>
	    <p>The functions <c>lists:seq/1,2</c> return the empty
	    list in a few cases when they used to generate an
	    exception, for example <c>lists:seq(1, 0)</c>. See
	    lists(3) for details. (Thanks to Richard O'Keefe.)</p>
          <p>
	    *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
	    Own Id: OTP-7230</p>
        </item>
        <item>
	    <p>Support for Unicode is implemented as described in
	    EEP10. Formatting and reading of unicode data both from
	    terminals and files is supported by the io and io_lib
	    modules. Files can be opened in modes with automatic
	    translation to and from different unicode formats. The
	    module 'unicode' contains functions for conversion
	    between external and internal unicode formats and the re
	    module has support for unicode data. There is also
	    language syntax for specifying string and character data
	    beyond the ISO-latin-1 range.</p>
	    <p>The interactive shell will support input and output of
	    unicode characters when the terminal and operating system
	    supports it.</p>
	    <p>Please see the EEP and the io/io_lib manual pages as
	    well as the stdlib users guide for details.</p>
	    <p><em>I/O-protocol incompatibilities:</em></p>
	    <p>The io_protocol between io_Server and client is
	    updated to handle protocol data in unicode formats. The
	    updated protocol is now documented. The specification
	    resides in the stdlib <em>users manual</em>, which is a
	    new part of the manual.</p>
	    <p><em>io module incompatibilities:</em></p>
	    <p>The io:put_chars, io:get_chars and io:get_line all
	    handle and return unicode data. In the case where
	    binaries can be provided (as to io:put_chars), they shall
	    be encoded in UTF-8. When binaries are returned (as by
	    io:get_line/get_chars when the io_server is set in
	    <em>binary mode</em>) the returned data is also
	    <em>always</em> encoded as UTF-8. The file module however
	    still returns byte-oriented data, why file:read can be
	    used instead of io:get_chars to read binary data in
	    ISO-latin-1.</p>
	    <p><em>io_lib module incompatibilities:</em></p>
	    <p>io_lib:format can, given new format directives (i.e
	    "~ts" and "~tc"), return lists containing integers larger
	    than 255. </p>
          <p>
	    *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
	    Own Id: OTP-7648 Aux Id: OTP-7580 OTP-7514 OTP-7494
	    OTP-7443 OTP-7181 EEP10 EEP11 </p>
        </item>
        <item>
          <p>
	    <c>filelib:fold_files/5</c> now uses the <c>re</c> module
	    instead of the <c>regexp</c> module for regular
	    expression matching. In practice, this change will not be
	    a problem for most regular expressions used for
	    <c>filelib:fold_files/5</c>. (The major difference in
	    regular expression is that parenthesis and curly brackets
	    is treated as literal characters by <c>regexp</c> but as
	    special characters by <c>re</c>; fortunately, those
	    characters are rarely used in filenames.)</p>
          <p>
	    *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
	    Own Id: OTP-7819</p>
        </item>
        <item>
          <p>
	    <c>digraph:new(Type)</c> will now cause a <c>badarg</c>
	    exception if <c>Type</c> is not a valid type. Similarly,
	    <c>digraph_utils:subgraph/2,3</c> will now cause a
	    <c>badarg</c> if the arguments are invalid. (Those
	    functions used to return error tuples if something was
	    wrong.)</p>
          <p>
	    *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
	    Own Id: OTP-7824</p>
        </item>
        <item>
	    <p>The argument passed to <c>random:uniform/1</c> must
	    now be an integer (as stated in the documentation). In
	    previous releases, a floating point number was also
	    allowed.</p>
          <p>
	    *** POTENTIAL INCOMPATIBILITY ***</p>
          <p>
	    Own Id: OTP-7827</p>
        </item>
    </list>
  </section>
</chapter>