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[SVN r8446]
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Beman Dawes
2000-12-10 15:53:46 +00:00
parent 53011de54d
commit bab5f86c1b
2 changed files with 29 additions and 27 deletions
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52
concept_check.htm
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@@ -11,7 +11,9 @@
-- purpose. It is provided "as is" without express or implied warranty.
-->
<Head>
<Title>Concept Checking</Title>
<Title>Concept Check Library</Title>
</head>
<BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b"
ALINK="#ff0000">
<IMG SRC="../../c++boost.gif"
@@ -19,7 +21,7 @@
<BR Clear>
<H1>The Boost Concept Checking Library (BCCL)</H1>
<H1>The Boost Concept Check Library (BCCL)</H1>
<h2>
<A NAME="sec:concept-checking"></A>
@@ -40,7 +42,7 @@ required concept as a hint to the user and to state the concept
requirements in the documentation. However, often times the
requirements are vague, incorrect, or nonexistent, which is quite a
problem for the user, since he or she will not know exactly what kind
of input is expected by the template. Furthemore, the following
of input is expected by the template. Furthermore, the following
problems occur:
<ul>
@@ -84,7 +86,7 @@ overhead. The main cost of using the mechanism is in compile-time.
<p>
Any programmer writing class or function templates ought to make
concept checking a normal part of their code-writing routine. A
concept check should be inserted for each template paramter in a
concept check should be inserted for each template parameter in a
component's public interface. If the concept is one of the ones from
the Standard Library, then simply use the matching concept checking
class in the BCCL. If not, then write a new concept checking class -
@@ -102,9 +104,9 @@ The documentation is organized into the following sections.
<LI><a href="#publications">Publications</a></LI>
<LI><a href="#acknowledgements">Acknowledgements</a></LI>
<LI><a href="./using_concept_check.htm">Using Concept Checks</a></LI>
<LI><a href="./creating_concept_checks.htm">Creating Concept Checking Classes</a></LI>
<LI><a href="creating_concepts.htm">Creating Concept Checking Classes</a></LI>
<LI><a href="./concept_covering.htm">Concept Covering and Archetypes</a></LI>
<LI><a href="./prog_with_concepts.htm"">Programming With Concepts</a></LI>
<LI><a href="./prog_with_concepts.htm" ">Programming With Concepts</a></LI>
<LI><a href="./implementation.htm">Implementation</a></LI>
<LI><a href="./reference.htm">Reference</a></LI>
</OL>
@@ -157,9 +159,9 @@ We present a simple example to illustrate incorrect usage of a
template library and the resulting error messages. In the code below,
the generic <tt>std::stable_sort()</tt> algorithm from the Standard
Template Library (STL)[<a
href="bibliography.html#austern99:_gener_progr_stl">3</a>, <a
href="bibliography.html#IB-H965502">4</a>,<a
href="bibliography.html#stepa.lee-1994:the.s:TR">5</a>] is applied to
href="bibliography.htm#austern99:_gener_progr_stl">3</a>, <a
href="bibliography.htm#IB-H965502">4</a>,<a
href="bibliography.htm#stepa.lee-1994:the.s:TR">5</a>] is applied to
a linked list.
<pre>
@@ -168,7 +170,7 @@ a linked list.
2 #include &lt;algorithm&gt;
3
4 struct foo {
5 bool operator&lt;(const foo&) const { return false; }
5 bool operator&lt;(const foo&amp;) const { return false; }
6 };
7 int main(int, char*[]) {
8 std::list&lt;foo&gt; v;
@@ -190,18 +192,18 @@ Appendix.
<pre>
stl_algo.h: In function `void __merge_sort_loop&lt;_List_iterator
&lt;foo,foo &,foo *&gt;, foo *, int&gt;(_List_iterator&lt;foo,foo &,foo *&gt;,
_List_iterator&lt;foo,foo &,foo *&gt;, foo *, int)':
&lt;foo,foo &amp;,foo *&gt;, foo *, int&gt;(_List_iterator&lt;foo,foo &amp;,foo *&gt;,
_List_iterator&lt;foo,foo &amp;,foo *&gt;, foo *, int)':
stl_algo.h:1448: instantiated from `__merge_sort_with_buffer
&lt;_List_iterator&lt;foo,foo &,foo *&gt;, foo *, int&gt;(
_List_iterator&lt;foo,foo &,foo *&gt;, _List_iterator&lt;foo,foo &,foo *&gt;,
&lt;_List_iterator&lt;foo,foo &amp;,foo *&gt;, foo *, int&gt;(
_List_iterator&lt;foo,foo &amp;,foo *&gt;, _List_iterator&lt;foo,foo &amp;,foo *&gt;,
foo *, int *)'
stl_algo.h:1485: instantiated from `__stable_sort_adaptive&lt;
_List_iterator&lt;foo,foo &,foo *&gt;, foo *, int&gt;(_List_iterator
&lt;foo,foo &,foo *&gt;, _List_iterator&lt;foo,foo &,foo *&gt;, foo *, int)'
_List_iterator&lt;foo,foo &amp;,foo *&gt;, foo *, int&gt;(_List_iterator
&lt;foo,foo &amp;,foo *&gt;, _List_iterator&lt;foo,foo &amp;,foo *&gt;, foo *, int)'
stl_algo.h:1524: instantiated from here
stl_algo.h:1377: no match for `_List_iterator&lt;foo,foo &,foo *&gt; & -
_List_iterator&lt;foo,foo &,foo *&gt; &'
stl_algo.h:1377: no match for `_List_iterator&lt;foo,foo &amp;,foo *&gt; &amp; -
_List_iterator&lt;foo,foo &amp;,foo *&gt; &amp;'
</pre>
In this case, the fundamental error is that
@@ -239,14 +241,14 @@ Library produces):
<pre>
boost/concept_check.hpp: In method `void LessThanComparableConcept
&lt;_List_iterator&lt;foo,foo &,foo *> >::constraints()':
&lt;_List_iterator&lt;foo,foo &amp;,foo *&gt; &gt;::constraints()':
boost/concept_check.hpp:334: instantiated from `RandomAccessIteratorConcept
&lt;_List_iterator&lt;foo,foo &,foo *> >::constraints()'
&lt;_List_iterator&lt;foo,foo &amp;,foo *&gt; &gt;::constraints()'
bad_error_eg.cpp:9: instantiated from `stable_sort&lt;_List_iterator
&lt;foo,foo &,foo *> >(_List_iterator&lt;foo,foo &,foo *>,
_List_iterator&lt;foo,foo &,foo *>)'
boost/concept_check.hpp:209: no match for `_List_iterator&lt;foo,foo &,foo *> &
&lt; _List_iterator&lt;foo,foo &,foo *> &'
&lt;foo,foo &amp;,foo *&gt; &gt;(_List_iterator&lt;foo,foo &amp;,foo *&gt;,
_List_iterator&lt;foo,foo &amp;,foo *&gt;)'
boost/concept_check.hpp:209: no match for `_List_iterator&lt;foo,foo &amp;,foo *&gt; &amp;
&lt; _List_iterator&lt;foo,foo &amp;,foo *&gt; &amp;'
</pre>
This message rectifies several of the shortcomings of the standard
@@ -290,7 +292,7 @@ The idea to use function pointers to cause instantiation is due to
Alexander Stepanov. I am not sure of the origin of the idea to use
expressions to do up-front checking of templates, but it did appear in
D&amp;E[
<a href="bibliography.html#stroustrup94:_design_evolution">2</a>].
<a href="bibliography.htm#stroustrup94:_design_evolution">2</a>].
Thanks to Matt Austern for his excellent documentation and
organization of the STL concepts, upon which these concept checks
are based. Thanks to Boost members for helpful comments and

4
implementation.htm
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@@ -24,7 +24,7 @@
Ideally we would like to catch, and indicate, the concept violation at
the point of instantiation. As mentioned in D&amp;E[<a
href="bibliography.html#stroustrup94:_design_evolution">2</a>], the error
href="bibliography.htm#stroustrup94:_design_evolution">2</a>], the error
can be caught by exercising all of the requirements needed by the
function template. Exactly how the requirements (the valid
expressions in particular) are exercised is a tricky issue, since we
@@ -189,7 +189,7 @@ type.
<p>
<a href="./reference.htm">Next: Reference</a><br>
<a href="./prog_with_concepts.html">Prev: Programming With Concepts</a>
<a href="prog_with_concepts.htm">Prev: Programming With Concepts</a>
<br>
<HR>