<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<META HTTP-EQUIV="CONTENT-TYPE" CONTENT="text/html; charset=utf-8">
<TITLE></TITLE>
<META NAME="GENERATOR" CONTENT="OpenOffice.org 2.4 (Linux)">
<META NAME="AUTHOR" CONTENT="Marcin Kuszczak">
<META NAME="CREATED" CONTENT="20081009;14222900">
<META NAME="CHANGED" CONTENT="20081011;22130700">
<STYLE TYPE="text/css">
<!--
@page { size: 29.7cm 21cm; margin: 1.5cm }
P { margin-bottom: 0.21cm }
TH P { font-weight: bold; text-align: center }
A:link { color: #000080; text-decoration: underline }
-->
</STYLE>
</HEAD>
<BODY LANG="pl-PL" LINK="#000080" VLINK="#800000" DIR="LTR">
<P LANG="en-US" ALIGN=CENTER STYLE="margin-bottom: 0cm"><FONT SIZE=4 STYLE="font-size: 16pt"><B>Uniform
syntax for compile-time expressions in D</B></FONT></P>
<P LANG="en-US" ALIGN=CENTER STYLE="margin-bottom: 0cm">
</P>
<UL>
<LI><P LANG="en-US" STYLE="margin-bottom: 0cm">Most examples are
real templates taken from Doost library:
www.dsource.org/projects/doost/</P>
<LI><P STYLE="margin-bottom: 0cm"><SPAN LANG="en-US">This is
slightly modified version of my change
proposal:<BR></SPAN><A HREF="http://d.puremagic.com/issues/show_bug.cgi?id=1827"><SPAN LANG="en-US">http://d.puremagic.com/issues/show_bug.cgi?id=1827</SPAN></A></P>
</UL>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><FONT SIZE=4><B>Proposed
syntax:</B></FONT></P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<P LANG="zxx" STYLE="margin-bottom: 0cm">ctexpr (bool) : (T [S1 S2
... Sn] [ ':' | '==' inexpr] ) | ct_bool_value</P>
<P LANG="zxx" STYLE="margin-bottom: 0cm">inexpr (bool) : pattern |
pattern if (ctexpr) | if(ctexpr)</P>
<P LANG="zxx" STYLE="margin-bottom: 0cm">pattern: type | derived
data type</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><FONT SIZE=4><B>Description:</B></FONT></P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><B>T</B> type identifier</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><B>S1..Sn</B> introduced
types</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><B>ct_bool_value</B> compile
time true or false</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><B>:</B> direct or
indirect type of ... (in case of value types: is implicitly
convertible)</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><B>==</B> is exact type
of ...</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><B>derived data type </B>e.g.
S[] S[N = size_t] , E[K], E[int], class, typedef, int, MyType!(int),
TheirType</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm">Passing by alias, default
type, default type and value examples are not taken into
consideration in above syntax description. Examples for these case
are in table below.</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm; border-top: none; border-bottom: 1px solid #000000; border-left: none; border-right: none; padding-top: 0cm; padding-bottom: 0.07cm; padding-left: 0cm; padding-right: 0cm">
<BR>
</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<OL>
<LI><P LANG="en-US" STYLE="margin-bottom: 0cm"><B>ctexpr</B> and
<B>pattern </B>evaluates to true or false</P>
</OL>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<OL START=2>
<LI><P LANG="en-US" STYLE="margin-bottom: 0cm">Both <B>pattern</B>
and <B>ctexpr</B> must be true, to match template function during
instantiation</P>
</OL>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<OL START=3>
<LI><P LANG="en-US" STYLE="margin-bottom: 0cm">Introduced symbols in
pattern are aliased with concrete types when evaluating <B>ctexpr</B></P>
</OL>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<OL START=4>
<LI><P LANG="en-US" STYLE="margin-bottom: 0cm">Symbols can have
fixed types. If reasonable when evaluating pattern symbols can have
also value e.g.:<BR><BR>void changeElement(T U N : U[N=uint]
if(N>100))(T array, U value, int index); <BR><BR>Above template
function matches all static arrays bigger than 100; N - number of
declared elements in s. array; N is binded to value of type uint.</P>
</OL>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<OL START=5>
<LI><P LANG="en-US" STYLE="margin-bottom: 0cm">Parts of <B>ctexpr</B>
can be omitted, so it looks exactly like current declarations
e.g.:<BR><BR><SPAN LANG="zxx">string stringize(T : bool)(bool
value); // omitted symbols and ctexpr<BR>string stringize(T)(T
value); // omitted symbols, ":" and </SPAN><SPAN LANG="zxx"><B>inexpr</B></SPAN></P>
</OL>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<OL START=6>
<LI><P LANG="en-US" STYLE="margin-bottom: 0cm">Initial T can not be
redefined; currently it is rather confusing that elephant transforms
into monkey in following:<BR>string stringize(T : T[])(T value);
//what should be passed to function? array or array element?<BR><BR>it
should be rather:<BR>string stringize(T U : U[])(T value); //now
everything is clear</P>
</OL>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<OL START=7>
<LI><P LANG="en-US" STYLE="margin-bottom: 0cm">Following definition
with three template arguments:<BR><BR>void parse(T E : E[], U :
bool, V E N : E[N] if(N>100))(T array, U flag, V sarray);<BR><BR>should
be just syntactic sugar for:<BR><BR>void parse(T E : E[] &&
U : bool && V E N : E[N] if (N>100))(T array, U flag, V
sarray) ;<BR><BR><B>Above is very complicated case which would be
possible, but currently it is not. Simple cases still stay simple as
it is now.</B></P>
</OL>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<OL START=8>
<LI><P LANG="en-US" STYLE="margin-bottom: 0cm">... is() for
metaprogramming can be dropped.</P>
</OL>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<OL START=9>
<LI><P LANG="en-US" STYLE="margin-bottom: 0cm">It is an error if
defined symbols are not used in inexpr or don't have assigned types
in ctexpr</P>
</OL>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<OL START=10>
<LI><P LANG="en-US" STYLE="margin-bottom: 0cm">If <B>inexpr</B> is
not defined T is aliased to all given symbols<BR><BR>
</P>
<LI><P LANG="en-US" STYLE="margin-bottom: 0cm">Template function
resolution (my guess that it would be possible). When resolving
template function name it might be possible to relay on ctexpr
resulting value. If compile-time time expression returns true, then
there is a match. In such a case it would be possible to create
templ. functions:<BR><SPAN LANG="zxx"><B>S
toupper(isSomeString!(S))(S input)</B></SPAN><BR>Although there
should be probably more calculations to know which function is more
specialized.</P>
</OL>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><FONT SIZE=4><B>With above
proposal there can be only one syntax for: static if(), template
(function) definition & static assert() & alias while is()
for metaprogramming can be safely dropped. This syntax is consistent
& extensible so it will allow to achieve much more.</B></FONT></P>
<P LANG="en-US" STYLE="margin-bottom: 0cm; border-top: none; border-bottom: 1px solid #000000; border-left: none; border-right: none; padding-top: 0cm; padding-bottom: 0.07cm; padding-left: 0cm; padding-right: 0cm">
<BR>
</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm; page-break-before: always">
<BR>
</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><FONT SIZE=4><B>Uniform
syntax by example</B>:</FONT></P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><B>Template (function)
compile-time arguments:</B></P>
<TABLE WIDTH=100% BORDER=1 BORDERCOLOR="#000000" CELLPADDING=4 CELLSPACING=0 STYLE="page-break-after: auto">
<COL WIDTH=85*>
<COL WIDTH=85*>
<COL WIDTH=85*>
<THEAD>
<TR VALIGN=TOP>
<TH WIDTH=33% BGCOLOR="#ffff66">
<P LANG="zxx"><FONT SIZE=3>Old</FONT></P>
</TH>
<TH WIDTH=33% BGCOLOR="#ffff66">
<P LANG="zxx"><FONT SIZE=3>New</FONT></P>
</TH>
<TH WIDTH=33% BGCOLOR="#ffff66">
<P LANG="en-US"><FONT SIZE=3>Comment</FONT></P>
</TH>
</TR>
</THEAD>
<TBODY>
<TR>
<TD COLSPAN=3 WIDTH=100% VALIGN=TOP BGCOLOR="#ffff99">
<P LANG="zxx" ALIGN=CENTER><FONT SIZE=3><B>Template function
compile-time arguments:</B></FONT></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">template
normalizedType(T)</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">template
normalizedType(T);</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><BR>
</P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">template
normalizedType(T : U[N], U, size_t N)</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">template
normalizedType(T U N : U[N=size_t])</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">Introduced
variables are before their usage</FONT></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">void
doIt(alias T E : E[])(E elem)</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">void
doIt(alias T E : E[])(E elem)</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">Alias
parameters; I am <SPAN LANG="zxx">not sure if condition checks
would work for aliases.</SPAN></FONT></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">void
doIt(T=string E : E[])(E elem)</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">void
doIt(string T E : E[])(E elem)</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">I am not sure
if checking condition works right now.</FONT></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">size_t
levenshteinDistance(string equals = "a == b", Range1,
Range2)(Range1 s, Range2 t)</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">size_t
levenshteinDistance(string equals = "a == b", Range1,
Range2)(Range1 s, Range2 t)</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">Default
template parameter value will stay same as before. Please notice
better consistency with situation when only type is default (row
above) than in current version. And more possibilities to specify
conditions.</FONT></P>
</TD>
</TR>
<TR>
<TD COLSPAN=3 WIDTH=100% VALIGN=TOP BGCOLOR="#ffff99">
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt"><B>Things
currently not possible:</B></FONT></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">void do(T :
class)(T instance);</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><BR>
</P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">void do(T E :
E[class])(T sarray, E element);</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">match
associative arrays with key as class</FONT></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">S
toupper(isSomeString!(S))(S input)</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">See point 11</FONT></P>
</TD>
</TR>
<TR>
<TD COLSPAN=3 WIDTH=100% VALIGN=TOP BGCOLOR="#ffff99">
<P LANG="zxx" ALIGN=CENTER><FONT SIZE=3><B>static if </B></FONT>
</P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">static if (is(T
: Storage!(STORAGETYPE)))</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">static if (T :
Storage!(STORAGETYPE))</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">'is' probably
can be safely dropped</FONT></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">static if
(is(VALUE TYPE == typedef))</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">static if
(VALUE TYPE == typedef)</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">1. This one
is a bit tricky. Alternative could be:</FONT></P>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">static if
(VALUE TYPE == typedef(TYPE))</FONT></P>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">to be exact
pattern matching without 'magic' <BR>2. Here I used '==' instead
of ':' It should mean that we are expecting <B>exact</B>
matches. Using ':' causes also indirect cases: derived classes
and types which can be implicitly casted. In many cases it will
be evaluated to exactly same result</FONT></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">static if (is(T
TYPE == TYPE*) || is(T == class))</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">static if (T
TYPE == TYPE* || T == class)</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><BR>
</P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">static if
(isString!(VALUE))</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">static if
(isString!(VALUE))</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">it should
still work as static if takes as parameter boolean <B>value</B>,
which is exactly what we get after evaluating isString!(T).</FONT></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">static if
(is(VALUE TYPE == TYPE*))</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">static if
(VALUE TYPE == TYPE*)</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><BR>
</P>
</TD>
</TR>
<TR>
<TD COLSPAN=3 WIDTH=100% VALIGN=TOP BGCOLOR="#ffff99">
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt"><B>Things
currently not possible:</B></FONT></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">static if (T :
Storage!(STORAGETYPE) if (T == MyType))</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><BR>
</P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">static if(T ==
invariant)</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">well I am not
much in const stuff, but uniform syntax opens door for this also.</FONT></P>
</TD>
</TR>
<TR>
<TD COLSPAN=3 WIDTH=100% VALIGN=TOP BGCOLOR="#ffff99">
<P LANG="zxx" ALIGN=CENTER><FONT SIZE=3><B>static assert</B></FONT></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">static
assert(is(VALUE : class), "Classes are not supported");</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">static
assert(VALUE : class, "Classes are not supported");</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><BR>
</P>
</TD>
</TR>
<TR>
<TD COLSPAN=3 WIDTH=100% VALIGN=TOP BGCOLOR="#ffff99">
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt"><B>Things
currently not possible:</B></FONT></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">static assert(V
E K : E[K] if (K == int), "Not supported");</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">Well, not
very good example because it is enough to write:</FONT></P>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">static
assert(V E : E[int], "Not supported");</FONT></P>
<P LANG="en-US"><BR>
</P>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">Just to get
idea what can be possible.</FONT></P>
</TD>
</TR>
<TR>
<TD COLSPAN=3 WIDTH=100% VALIGN=TOP BGCOLOR="#ffff99">
<P LANG="zxx" ALIGN=CENTER><B>alias syntax</B></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">alias
Variant[][] table;</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">alias
Variant[][] table;</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><BR>
</P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><BR>
</P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><BR>
</P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><BR>
</P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><BR>
</P>
</TD>
</TR>
<TR>
<TD COLSPAN=3 WIDTH=100% VALIGN=TOP BGCOLOR="#ffff99">
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt"><B>Things
currently not possible:</B></FONT></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">alias
Variant[][] A B C;</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">aliases
Variant[][] to all symbols: A and B and C</FONT></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">alias T U :
U[];</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">simple
decomposition of types<BR>aliases U to element type of T; if the
whole compile-time expression evaluates to false it is
compile-time error.<BR>currently it is necessary to use
artificial static if () statement to decompose type.</FONT></P>
</TD>
</TR>
<TR VALIGN=TOP>
<TD WIDTH=33%>
<P LANG="zxx"><BR>
</P>
</TD>
<TD WIDTH=33%>
<P LANG="zxx"><FONT SIZE=2 STYLE="font-size: 9pt">alias T U N :
U[N=uint] if (N>100);</FONT></P>
</TD>
<TD WIDTH=33%>
<P LANG="en-US"><FONT SIZE=2 STYLE="font-size: 9pt">aliases U to
static array element type; and N to value of type uint, but only
if size of static array is bigger than 100.</FONT></P>
</TD>
</TR>
</TBODY>
</TABLE>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
<P LANG="en-US" STYLE="margin-bottom: 0cm"><BR>
</P>
</BODY>
</HTML>