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legacy.html
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<html>
<head>
<title>Legacy Words</title>
<style type="text/css">
ol li { margin-left: -1em; }
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ul.results { margin-left: 0em; padding-left: 20px; }
ul.results li { margin-bottom: 1ex; }
ul.results li:first-line { font-weight: bold; }
.history dd { margin-bottom: 1ex; }
.def dd { margin-bottom: 2ex; }
</style>
</head>
<body>
<h3>Legacy Words (v4)</h3>
<p>
[ <a href="rfds.html">RfDs/CfVs</a> | <a href="proposals.html">Other proposals</a> ]
</p>
<h3>Poll Standings</h3>
See <a href="#voting">below</a> for voting instructions.
<h4>Systems</h4>
<dl>
<dt> [ ] I agree with the proposed alteration to the document text.</dt>
<dd>Gerry Jackson<br/>
Hans Bezemer<br/>
Bernd Paysan<br/>
Marcel Hendrix
</dd>
<dt> [ ] I do not agree with the proposed alteration to the document text.</dt>
<dd>Leon Wagner</dd>
</dl>
<h4>Informal Results</h4>
<ul class="results">
<li>Leon Wagner<br/>
I am opposed to bringing back <code>FORGET</code>. I would agree to keeping
the obsolescent word set with exactly one member: <code>FORGET</code>.
</li>
<li>Hans Bezemer<br/>
I have no problems they are disappearing. However, due to 4tH I/O architecture
I will continue to use <code>TIB</code> as a constant to designate the built-in <code>TIB</code>
address. Otherwise it would be impossible for a user to reset the <code>SOURCE!</code>
(Sourceforge) to the standard built-in buffer. The second word is <code>/TIB</code>, but
that is non-standard anyway.
</li>
<li> Marcel Hendrix<br/>
"As a concession to the obsolesecent word <code>CONVERT</code>, " should be
"As a concession to the obsolescent word <code>CONVERT</code>, "
<p/>
"If the input source is coming from the user <code>REFILL</code> could still return a
false value if, for instance, a communication channel closes so that the
system knows that no more input will be available. "
could be
"If the input source is coming from the user, REFILL could still return a
false value if, for instance, a communication channel closes so that the
system knows that no more input will be available. "
</li>
</ul>
<table width="500"><tr><td>
<h3>Problem</h3>
Section 1.4.2 "Obsolescent features" declared seven words as
obsolescent and warned "<em>they may be withdrawn from future revisions
of the Standard</em>". It is now 15 years since that warning was issued,
it is time to remove these words from the document.
<p/>
In order to do this a number of alterations to the main document
are required.
<h3>Proposal</h3>
<ol>
<li>
Replace the first three paragraphs of section 1.4.2 "Obsolescent
features", listing the obsolescent words:
<blockquote>
This Standard adopts certain words and practices that cause some
previously used words and practices to become obsolescent.
Although retained here because of their widespread use, their
use in new implementations or new programs is discouraged,
because they may be withdrawn from future revisions of the
Standard.
<p/>
This Standard designates the following words as obsolescent:
<p/>
<table><tr>
<td>6.2.0060</td> <td><code>#TIB</code></td><td></td>
<td>15.6.2.1580</td><td><code>FORGET</code></td><td></td>
<td>6.2.2240</td> <td><code>SPAN</code></td>
</tr><tr>
<td>6.2.0970</td> <td><code>CONVERT</code></td><td></td>
<td>6.2.2040</td> <td><code>QUERY</code></td><td></td>
<td>6.2.2290</td> <td><code>TIB</code></td>
</tr><tr>
<td>6.2.1390</td> <td><code>EXPECT</code></td>
</tr>
</table>
</blockquote>
with:
<blockquote>
This Standard adopts certain words and practices that cause some
previously used words and practices to become obsolescent.
Their use in new implementations or new programs is discouraged,
as they may be withdrawn from future revisions of the Standard.
<p/>
This Standard designates no words as obsolescent.
</blockquote>
</li><li>
Remove reference to <code>EXPECT</code> and <code>CONVERT</code> from the Documentation
requirements:
<dl class="history">
<dt>4.1.1 Implementation-defined options:</dt>
<dd>character editing of <code>ACCEPT</code> and <code>EXPECT</code>;</dd>
<dd>display after input terminates in <code>ACCEPT</code> and <code>EXPECT</code>;</dd>
<dt>4.1.2 Ambiguous conditions</dt>
<dd>producing a result out of range, e.g., multiplication
(using <code>*</code>) results in a value too big to be represented by a
single-cell integer (<code>*</code>, <code>*/</code>, <code>*/MOD</code>, <code>>NUMBER</code>, <code>FM/MOD</code>, <code>SM/REM</code>,
<code>UM/MOD</code>, <code>CONVERT</code>, <code>M*/</code>);
</dd>
<dt>4.2.1 Environmental dependencies</dt>
<dd>depending on the presence or absence of non-graphic
characters in a received string (<code>ACCEPT</code>, <code>EXPECT</code>);</dd>
</dl>
</li><li>
CORE EXT Wordset
<dl class="history">
<dt>6.1.2216 <code>SOURCE</code></dt>
<dd>
Remove ", declaring <code>TIB</code> and <code>#TIB</code> obsolescent" from the end of the
first paragraph, and the following text from the rationale:
<blockquote>
<code>SOURCE</code> in this form exists in F83, polyFORTH, LMI's Forths and
others. In conventional systems it is equivalent to the phrase
<blockquote>
<code>BLK @ IF BLK @ BLOCK 1024 ELSE TIB #TIB @ THEN</code>
</blockquote>
</blockquote>
</dd>
<dt>6.1.2450 <code>WORD</code></dt>
<dd>
Remove the sentence "A space, not included in the length, follows
the string" from the second paragraph and the note in the definition.
<p/>
Remove the second paragraph from the rationale:
<blockquote>
As a concession to the obsolesecent word <code>CONVERT</code>, Forth94
required an implementation to put a space after the string
placed by <code>WORD</code>. This standard neither requires nor prohibits
such a space.
</blockquote>
</dd>
<dt>6.2.0060 #TIB</dt>
<dd>
Remove the definition and rationale.
</dd>
<dt>6.2.0695 ACCEPT</dt>
<dd>
Remove reference to <code>EXPECT</code> from the first paragraph, and the
following paragraphs from the rationale:
<blockquote>
<code>ACCEPT</code> and <code>EXPECT</code> perform similar functions. <code>ACCEPT</code> is
recommended for new programs, and future use of <code>EXPECT</code>
is discouraged.
<p/>
As in previous standards, <code>EXPECT</code> returns the input string
immediately after the requested number of characters are
entered, as well as when a line terminator is received.
The "automatic termination after specified count of
characters have been entered" behavior is widely considered
undesirable because the user "loses control" of the input
editing process at a potentially unknown time (the user does
not necessarily know how many characters were requested from
<code>EXPECT</code>). Thus <code>EXPECT</code> and <code>SPAN</code> have been made obsolescent and
exist in the Standard only as a concession to existing
implementations. If <code>EXPECT</code> exists in a Standard System it
must have the "automatic termination" behavior.
<p/>
<code>ACCEPT</code> does not have the "automatic termination" behavior of
<code>EXPECT</code>. However, because external system hardware and
software may perform the <code>ACCEPT</code> function, when a line
terminator is received the action of the cursor, and therefore
the display, is implementation-defined. It is recommended
that the cursor remain immediately following the entered text
after a line terminator is received.
</blockquote>
</dd>
<dt>6.2.0970 <code>CONVERT</code></dt>
<dd>
Remove the definition and rationale.
</dd>
<dt>6.2.1390 <code>EXPECT</code></dt>
<dd>
Remove the definition and rationale.
</dd>
<dt>6.2.2040 <code>QUERY</code></dt>
<dd>
Remove the definition and rationale.
</dd>
<dt>6.2.2125 <code>REFILL</code></dt>
<dd>
Remove the reference to <code>QUERY</code> in the rationale leaving:
<blockquote>
<code>REFILL</code> is designed to behave reasonably for all possible
input sources. If the input source is coming from the user
<code>REFILL</code> could still return a false value if, for instance, a
communication channel closes so that the system knows that
no more input will be available.
</blockquote>
</dd>
<dt>6.2.2240 <code>SPAN</code></dt>
<dd>
Remove the definition, there is no rationale.
</dd>
<dt>6.2.2290 <code>TIB</code></dt>
<dd>
Remove the definition and rationale.
</dd>
</dl>
</li><li>
TOOLS EXT Wordset
<dl class="history">
<dt>15.6.2.1580 <code>FORGET</code></dt>
<dd>
Remove the following note from the end of the third paragraph:
<blockquote>
Note: This word is obsolescent and is included as a
concession to existing implementations.
</blockquote>
</dd>
<dt>A.15.6.2.1580 <code>FORGET</code></dt>
<dd>
Replace the existing rationale:
<blockquote>
Typical use:
<blockquote>
... <code>FORGET</code> <em>name</em> ...
</blockquote>
<code>FORGET</code> assumes that all the information needed to restore the
dictionary to its previous state is inferable somehow from the
forgotten word. While this may be true in simple linear
dictionary models, it is difficult to implement in other Forth
systems; e.g., those with multiple address spaces. For example,
if Forth is embedded in ROM, how does <code>FORGET</code> know how much RAM
to recover when an array is forgotten? A general and preferred
solution is provided by <code>MARKER</code>.
</blockquote>
with the text:
<blockquote>
Typical use:
<blockquote>
... <code>FORGET</code> <em>name</em> ...
</blockquote>
<code>FORGET</code> tries to infer information about the previous dictionary
state from the forgotten word, which is not always possible. In
consequence, <code>FORGET</code> is guaranteed to restore the state of name
space, but not necessarily the state of dictionary.
<p/>
For example,
<blockquote><code><pre>
ALIGN HERE 100 CELLS ALLOT CONSTANT mybuffer
FORGET mybuffer
</pre></code></blockquote>
in this case the 100 reserved cells are a part of the buffer,
but <code>FORGET</code> can not infer this. A solution to the restoration
of the dictionary state is provided by <code>MARKER</code>.
<p/>
Nevertheless, <code>FORGET</code> is a useful tool for interactive sessions,
because it does not require creation of a marker in advance.
An example session may look like following:
<blockquote><code><pre>
: foo ... foo ... ( buggy redefinition) ;
\ finding out the bug
FORGET foo
: foo ... foo ... ( bug fixed) ;
\ checking that it works
\ copying the definition of foo into a file
</pre></code></blockquote>
It should be noted that such sessions are practical only in
environments that support input history (often persistent) and
copy/paste to/from the console.
</blockquote>
</dd>
</dl>
</li><li>
Remove the reference to <code>#TIB</code> and <code>TIB</code> from the first sentence of
the "Data space" rationale (A.3.3.3).
</li><li>
Remove the reference to <code>CONVERT</code> in the rationale for the
Core extension words (A.6.2):
<blockquote>
Words that are being deprecated in favour of new words
introduced to solve specific problems (e.g., <code>CONVERT</code>).
</blockquote>
</li><li>
Add the following to Annex D:
<blockquote>
<h3>D.7 ANS Forth '94</h3>
<h3>D.7.1 Removed Definitions</h3>
This standard removes six words that were marked 'obsolescent'
in the ANS Forth '94 document. These are:
<table><tr>
<td>6.2.0060</td> <td><code>#TIB</code></td><td></td>
<td>6.2.1390</td> <td><code>EXPECT</code></td><td></td>
<td>6.2.2240</td> <td><code>SPAN</code></td>
</tr><tr>
<td>6.2.0970</td> <td><code>CONVERT</code></td><td></td>
<td>6.2.2040</td> <td><code>QUERY</code></td><td></td>
<td>6.2.2290</td> <td><code>TIB</code></td>
</tr><tr>
<td></td> <td><code></code></td>
</tr>
</table>
Reuse of these names is strongly discouraged.
</blockquote>
</li>
</ol>
<h3>Remarks</h3>
Annex D needs work to bring it up to date, let along explain the
difference between Forth200x and ANS Forth '94. This should be
the topic of another RfD. The text given in point 9 is intended
as a place holder until annex D is discussed in full.
<p/>
The new rationale for <code>FORGET</code> is taken from Michael
Gassanenko's "<a href="unobsolete-forget.txt">un-obsolete <code>FORGET</code></a>".
</td></tr></table>
<h3>Change History</h3>
<dl class="history">
<dt>2010-09-01 v4 (PJK)</dt>
<dd>Removed <code>FORGET</code> from the list of obsolete words, reinstating it as a <code>TOOL EXT</code> word, with Gassanenko's rationale.
</dd>
<dt>2010-08-31 v3 (PJK)</dt>
<dd>Removed <code>FORGET</code> from the list of words removed, leaving it marked as obsolete</dd>
<dt>2009-09-09 v2 (PJK)</dt>
<dd>Removed legacy word set in favour of section D.7</dd>
<dt>1998-11-30 v1 (LZ)</dt>
<dd>Original text by Len Zettel</dd>
</dl>
<h3>Credits</h3>
Peter Knaggs <pjk<em>@</em>bcs<em>.</em>org<em>.</em>uk><br/>
Engineering, Mathematics and Physical Sciences,<br/>
University of Exeter, Exeter, Devon EX4 7QF, England<br/>
web: <a href="http://www.rigwit.co.uk">www.rigwit.co.uk</a>
</p>
<a name="voting"><h3>Voting Instructions</h3></a>
Fill out the ballot below and email it <vote@forth200x.org>.
Your vote will be published (including your name (without email
address) and/or the name of your system) here. You can vote (or
change your vote) at any time, and the results will be published
here.
<p>
<h4>Ballot</h4>
Please mark the statements that are correct for you
(e.g., by putting an ":<em>x</em>" between the brackets).
<dl>
<dt>[ ] I agree with the proposed alteration to the document text.</dt>
<dt>[ ] I do not agree with the proposed alteration to the document text.</dt>
</dl>
If you feel that the text does not cover all the aspects you would
expect, then please make an informal comment. These will be reported
in addition to the formal votes. Note that the best time to voice
such issues is the RfD stage. Alternatively, you could propose a
counter RfD.
</body>
</html>