Unfortunately, my proposal was not picked up this year. I might try to work on these ideas this summer anyway so I would still be very much interested in ideas and feedback, but I will probably have much less time if I'll be working somewhere else.<br clear="all">
<div><br></div><div>---</div>Cristi Cobzarenco<div>BSc in Artificial Intelligence and Computer Science</div><div>University of Edinburgh<br>Profile: <a href="http://www.google.com/profiles/cristi.cobzarenco" target="_blank">http://www.google.com/profiles/cristi.cobzarenco</a></div>
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<div class="gmail_extra"><br><br><div class="gmail_quote">On 10 April 2012 12:31, Cristi Cobzarenco <span dir="ltr"><<a href="mailto:cristi.cobzarenco@gmail.com" target="_blank">cristi.cobzarenco@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Timon is, of course, right. I got a bit confused when trying to simplify in a hurry. What I meant was actually something like this:<div>
<br><div>ops.d:</div><div><div>import std.stdio;</div><div><br></div><div>int sum( T )( T mat ){</div>
<div><span style="white-space:pre-wrap"> </span>writeln("ops.sum");</div><div><span style="white-space:pre-wrap"> </span>// return reduce!"a+b"( 0, mat );</div><div>
<span style="white-space:pre-wrap"> </span>return 1;</div><div>}</div><div><br></div><div>int numelems( T )( T mat ) {</div><div><span style="white-space:pre-wrap"> </span>// return mat.rows * mat.columns;</div>
<div><span style="white-space:pre-wrap"> </span>return 1;</div><div>}</div><div><br></div><div>int mean( T )( T mat ) {</div><div><span style="white-space:pre-wrap"> </span>return sum( mat ) / numelems( mat );</div>
<div>}</div><div><br></div></div><div>diagonal.d:</div><div><div>import ops;</div><div>import std.stdio;</div><div><br></div><div>struct DiagonalMatrix {</div><div><span style="white-space:pre-wrap"> </span></div>
<div>}</div><div><br></div><div>int sum( T : DiagonalMatrix )( T mat ) {</div><div><span style="white-space:pre-wrap"> </span>writeln( "diagonal.sum" );</div><div><span style="white-space:pre-wrap"> </span>// return reduce!"a+b"( 0, mat.diagonal() );</div>
<div><span style="white-space:pre-wrap"> </span>return 1;</div><div>} </div></div><div><br></div><div>main.d:</div><div>import ops;</div><div>import diagonal;</div><div><br></div><div><div>void main() {</div>
<div><span style="white-space:pre-wrap"> </span>DiagonalMatrix mat;</div><div><span style="white-space:pre-wrap"> </span>sum( mat ); // this will not compile, but if removed mean</div>
<div><span style="white-space:pre-wrap"> </span>mean( mat ); // will use ops.sum, not diagonal.sum anyway</div></div><div>}</div><div><br></div><div>The first problem could, in theory, be fixed using a member flag, something like enum specializedSum = true; and ops.sum could be redefined as: int sum( T )( T mat ) if( !T.specializedSum ) {}. But in this case mean() would still try to use ops.sum which will fail. All of this can be easily fixed by providing member functions, and having the free functions call the member ones when they exist.</div>
<div><div class="im"><div><br></div><div>---</div>Cristi Cobzarenco<div>BSc in Artificial Intelligence and Computer Science</div><div>University of Edinburgh<br>Profile: <a href="http://www.google.com/profiles/cristi.cobzarenco" target="_blank">http://www.google.com/profiles/cristi.cobzarenco</a></div>
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<br><br></div><div><div class="h5"><div class="gmail_quote">On 10 April 2012 10:35, Timon Gehr <span dir="ltr"><<a href="mailto:timon.gehr@gmx.ch" target="_blank">timon.gehr@gmx.ch</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>On 04/10/2012 03:24 AM, Cristi Cobzarenco wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Thanks for the suggestions!<br>
<br>
I don't think UFCS would help us. Our problem is that we can't do this:<br>
triangular.d:<br>
struct TriangularMatrix {<br>
<br>
}<br>
<br>
void sum( T )( T x ) if( is( T : TriangularMatrix ) ) {<br>
<br>
}<br>
<br>
diagonal.d:<br>
struct DiagonalMatrix {<br>
<br>
}<br>
<br>
void sum( T )( T x ) if( is( T : DiagonalMatrix ) ) {<br>
}<br>
<br>
main.d:<br>
import diagonal;<br>
import triangular;<br>
<br>
void bar() {<br>
TriangularMatrix a;<br>
Diagonal b;<br>
sum( a ); // this does not compile because sum() is ambiguous<br>
sum( b ); // nor does this<br>
}<br>
</blockquote>
<br></div>
There are no ambiguities in that example, and if ambiguities occur, they can always be fixed manually.<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>
<br>
This, AFAIK, is deliberate to avoid name hijacking - ADL in C++ had its<br>
share of criticism. I doubt we will ever get this behaviour in D and<br>
that is perhaps a good thing. I may have misunderstood UFCS though - or<br>
what you meant by making non-member function calls look nicer - please<br>
correct me if that's the case.<br>
<br>
Don't worry about long names, t() is already the way transposition is<br>
defined SciD. Moreover, it's a property so you can actually do "a.t * a"<br>
- convenience galore. I'm also considering of creating a submodule like<br>
std.linalg.short which defines aliases with short names for types and<br>
free functions - this will allow particularly numerics-heavy functions<br>
to be written more compactly. I'm not entirely sure it would be a good<br>
idea though as it may sacrifice readability where it's most needed.<br>
<br></div><div>
---<br>
Cristi Cobzarenco<br>
BSc in Artificial Intelligence and Computer Science<br>
University of Edinburgh<br>
Profile: <a href="http://www.google.com/profiles/cristi.cobzarenco" target="_blank">http://www.google.com/<u></u>profiles/cristi.cobzarenco</a><br>
<br>
</div></blockquote>
<br>
If you change 'Diagonal' to 'DiagonalMatrix', this compiles fine.<br>
<br>
</blockquote></div><br></div></div></div></div>
</blockquote></div><br></div>