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Add FAQ why use_count()?

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[SVN r10604]
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Beman Dawes
2001-07-13 14:07:08 +00:00
parent 65c3f2dc85
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1 changed files with 11 additions and 7 deletions
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shared_ptr.htm
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@ -227,24 +227,28 @@ implementation.   The
instantiation of member functions which require a complete type occurs in the <a href="shared_ptr_example2.cpp">shared_ptr_example2.cpp</a> instantiation of member functions which require a complete type occurs in the <a href="shared_ptr_example2.cpp">shared_ptr_example2.cpp</a>
implementation file.</p> implementation file.</p>
<h2><a name="FAQ">Frequently Asked Questions</a></h2> <h2><a name="FAQ">Frequently Asked Questions</a></h2>
<p><b>Q</b>. Why doesn't <b>shared_ptr</b> have template parameters supplying <p><b>Q.</b> Why doesn't <b>shared_ptr</b> have template parameters supplying
traits or policies to allow extensive user customization?<br> traits or policies to allow extensive user customization?<br>
<b>A</b>. Parameterization discourages users.&nbsp; <b>Shared_ptr</b> is <b>A.</b> Parameterization discourages users.&nbsp; <b>Shared_ptr</b> is
carefully crafted to meet common needs without extensive parameterization. carefully crafted to meet common needs without extensive parameterization.
Someday a highly configurable smart pointer may be invented that is also very Someday a highly configurable smart pointer may be invented that is also very
easy to use and very hard to misuse.&nbsp; Until then, <b>shared_ptr</b> is the easy to use and very hard to misuse.&nbsp; Until then, <b>shared_ptr</b> is the
smart pointer of choice for a wide range of applications.&nbsp; (Those smart pointer of choice for a wide range of applications.&nbsp; (Those
interested in policy based smart pointers should read <a href="http://cseng.aw.com/book/0,,0201704315,00.html">Modern interested in policy based smart pointers should read <a href="http://cseng.aw.com/book/0,,0201704315,00.html">Modern
C++ Design</a> by Andrei Alexandrescu.)</p> C++ Design</a> by Andrei Alexandrescu.)</p>
<p><b>Q</b>. Why doesn't <b>shared_ptr</b> use a linked list implementation?<br> <p><b>Q.</b> Why doesn't <b>shared_ptr</b> use a linked list implementation?<br>
<b>A</b>. A linked list implementation does not offer enough advantages to <b>A.</b> A linked list implementation does not offer enough advantages to
offset the added cost of an extra pointer.&nbsp; See <a href="smarttests.htm">timings</a> offset the added cost of an extra pointer.&nbsp; See <a href="smarttests.htm">timings</a>
page.</p> page.</p>
<p><b>Q</b>. Why don't <b>shared_ptr</b> (and the other Boost smart pointers) <p><b>Q.</b> Why don't <b>shared_ptr</b> (and the other Boost smart pointers)
supply an automatic conversion to <b>T*</b>?<br> supply an automatic conversion to <b>T*</b>?<br>
<b>A</b>. Automatic conversion is believed to be too error prone.</p> <b>A.</b> Automatic conversion is believed to be too error prone.</p>
<p><b>Q.</b> Why does <b>shared_ptr</b> supply use_count()?<br>
<b>A.</b> As an aid to writing test cases and debugging displays. One of the
progenitors had use_count(), and it was useful in tracking down bugs in a
complex project that turned out to have cyclic-dependencies.</p>
<hr> <hr>
<p>Revised <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan -->12 July, 2001<!--webbot bot="Timestamp" endspan i-checksum="21065" --> <p>Revised <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan -->13 July, 2001<!--webbot bot="Timestamp" endspan i-checksum="21067" -->
</p> </p>
<p><EFBFBD> Copyright Greg Colvin and Beman Dawes 1999. Permission to copy, use, <p><EFBFBD> Copyright Greg Colvin and Beman Dawes 1999. Permission to copy, use,
modify, sell and distribute this document is granted provided this copyright modify, sell and distribute this document is granted provided this copyright