允许函数指针代码处理成员函数 [英] Allowing function pointer code to work on a member function
问题描述
大家好
我有一个令我困惑的难题。
我在C中有一个很大的代码库，我尽可能快地转换为C ++
（也就是说，因为我不断学习新的习语和绊倒C ++
''features' ）。 C代码的一部分是一些优化函数，
期望指向函数的指针，该函数发送一个双精度数组并返回
a double即简化..
void optimize（double（* funk）（double *））;
我现在有一堆带有成员函数的类也需要加倍*
并返回我想在此优化器中使用的双倍，但编译器
不会让我因为：
错误：类型''double（namespace :: class ::）（double *）''的参数没有
匹配''double（*）（double *）''
好的 - 我没想过，但觉得必须有一个简单的答案。
但是，我尝试将这些函数声明为朋友（但
函数使用的类成员不再可用）和
向他们发送''指针''和BS BSPPL p.419：
typedef double（class :: * Pstd_mem）（怀疑le * pv）;
Pstd_mem p =& class :: opt_ll;
...但到目前为止我没有尝试过任何工作而且我正在运行出于想法。可以
任何C ++专家都提出了一个解决方案（希望可靠，并且有效率高达b $ b）？
TIA并请CC在这里回复
Michael
_ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ / _ /
_ / _ / _ / _ / _ / Hopkins Research Ltd
_ / _ / _ / _ /
_ / _ / _ / _ / _ / _ / _ / http：//www.hopkins-research .com /
_ / _ / _ / _ /
_ / _ / _ / _ /''触摸未来''
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[见 http://www.gotw.ca/resources/clcm.htm for info about
[comp.lang.c ++。moderated。第一次海报：做到这一点！ ]
Hi all
I have a conundrum that is puzzling me.
I have a large codebase in C that I am converting to C++ as fast as possible
(i.e. slowly because I keep learning new idioms and stumbling with C++
''features''). One part of the C code is some optimisation functions that
expect a pointer to a function which is sent an array of doubles and returns
a double i.e. simplified..
void optimise( double (*funk)( double* ) );
I now have a bunch of classes with member functions which also take double*
and return double that I want to use in this optimiser, but the compiler
won''t let me because:
error: argument of type ''double (namespace::class::)(double*)'' does not
match ''double (*)(double*)''
OK - I hadn''t thought about that but felt there must be an easy answer.
However, I have tried declaring the functions in question as friends (but
the class members that the functions use are no longer available) and
sending ''pointers'' to them a la BS TCPPPL p.419:
typedef double (class::*Pstd_mem)( double* pv );
Pstd_mem p = &class::opt_ll;
...but nothing I have tried so far works and I am running out of ideas. Can
any C++ gurus out there suggest a solution (that is hopefully reliable and
efficient)?
TIA and please CC replies here
Michael
_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
_/ _/ _/_/_/ Hopkins Research Ltd
_/ _/ _/ _/
_/_/_/_/ _/_/_/ http://www.hopkins-research.com/
_/ _/ _/ _/
_/ _/ _/ _/ ''touch the future''
_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
[ comp.lang.c++.moderated. First time posters: Do this! ]
推荐答案
查询，Hopkins Research写道：
Enquiries, Hopkins Research wrote:
我在C中有一个很大的代码库，我是尽可能快地转换为C ++（即缓慢因为我不断学习新的习语和使用C ++''功能''的绊脚石）。 C代码的一部分是一些优化函数，它们期望指向一个函数的指针，该函数发送一个双精度数组并返回一个双精度函数。
void优化（double（* funk）（double *））;
我现在有一堆带有成员函数的类，它们也会使用
double *并返回我希望在此优化器中使用的double ，但是
编译器不会让我因为：
错误：类型''double（namespace :: class ::）（double *）''的参数
不匹配''double（*）（double *）''
它们是不兼容的。
请参阅有关成员指针的常见问题解答。您可以在此处找到常见问题解答：
http：// www。 parashift.com/c++-faq-lite/
[..]
I have a large codebase in C that I am converting to C++ as fast as
possible (i.e. slowly because I keep learning new idioms and
stumbling with C++ ''features''). One part of the C code is some
optimisation functions that expect a pointer to a function which is
sent an array of doubles and returns a double i.e. simplified..
void optimise( double (*funk)( double* ) );
I now have a bunch of classes with member functions which also take
double* and return double that I want to use in this optimiser, but
the compiler won''t let me because:
error: argument of type ''double (namespace::class::)(double*)'' does
not match ''double (*)(double*)''
They are incompatible.
See FAQ about pointers to members. You can find the FAQ here:
http://www.parashift.com/c++-faq-lite/
[..]
如果你有疑问阅读常见问题，请问他们。
V
If you''ll have questions after reading the FAQ, do ask them.
V
查询，Hopkins Research写道：
Enquiries, Hopkins Research wrote:
大家好
我有一个令我困惑的难题。
我在C中有一个很大的代码库，我正在尽快转换为C ++
（即慢慢地因为我不断学习新的习语和绊倒C ++
''features''）。 C代码的一部分是一些优化函数，它们希望指向一个函数的指针，该函数被发送一个双精度数组并返回一个双精度函数，即简化...
void优化（double（* funk）（double *））;
我现在有一堆带有成员函数的类，它们也需要使用double *
并返回我想在此优化器中使用的double ，但编译器不会让我因为：
错误：类型''double（namespace :: class ::）（double *）''的参数不是
匹配''double（*）（double *）''
好的 - 我没想过，但觉得必须有一个简单的答案。
但是，我有尝试将这些函数声明为朋友（但是函数使用的类成员不再可用）和
向他们发送''指针'到la BS TCPPPL p.419：
typedef double（class :: * Pstd_mem）（double * pv）;
Pstd_mem p =& class :: opt_ll;
..但到目前为止我没有尝试过任何工作，而且我的想法已经不多了。那些任何C ++专家都可以建议一个解决方案（希望可靠且高效）？
Hi all
I have a conundrum that is puzzling me.
I have a large codebase in C that I am converting to C++ as fast as possible
(i.e. slowly because I keep learning new idioms and stumbling with C++
''features''). One part of the C code is some optimisation functions that
expect a pointer to a function which is sent an array of doubles and returns
a double i.e. simplified..
void optimise( double (*funk)( double* ) );
I now have a bunch of classes with member functions which also take double*
and return double that I want to use in this optimiser, but the compiler
won''t let me because:
error: argument of type ''double (namespace::class::)(double*)'' does not
match ''double (*)(double*)''
OK - I hadn''t thought about that but felt there must be an easy answer.
However, I have tried declaring the functions in question as friends (but
the class members that the functions use are no longer available) and
sending ''pointers'' to them a la BS TCPPPL p.419:
typedef double (class::*Pstd_mem)( double* pv );
Pstd_mem p = &class::opt_ll;
..but nothing I have tried so far works and I am running out of ideas. Can
any C++ gurus out there suggest a solution (that is hopefully reliable and
efficient)?
自由函数和成员函数是不同的。请参阅
http：// www .parashift.com / c ++ - faq-lit ... o-members.html ，
特别是33.2。当你在那里，阅读整个常见问题，它可能会帮助你。
Jonathan
[见 http://www.gotw.ca/resources/clcm.htm 有关的信息]
[comp.lang.c ++。moderated。第一次海报：做到这一点！ ]
Free functions and member functions are different. See
http://www.parashift.com/c++-faq-lit...o-members.html,
especially 33.2. While you''re there, read the whole faq, it may help
you.
Jonathan
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
[ comp.lang.c++.moderated. First time posters: Do this! ]
2005年10月22日星期六13:48:30 -0400，Victor Bazarov < v。******** @ comAcast.net>
写道：
On Sat, 22 Oct 2005 13:48:30 -0400, "Victor Bazarov" <v.********@comAcast.net>
wrote:
我现在有一堆带有成员函数的类，它们也需要使用
double *并返回我想在此优化器中使用的double，但编译器不会让我因为：
error：类型''double（namespace :: class ::）（double *）''的参数确实
不匹配''double（*）（double *）''
I now have a bunch of classes with member functions which also take
double* and return double that I want to use in this optimiser, but
the compiler won''t let me because:
error: argument of type ''double (namespace::class::)(double*)'' does
not match ''double (*)(double*)''
它们是不兼容的。
They are incompatible.
但你可以用它们指向_static_成员函数，这可能会令人满意
OP'的目标。
-dr
But you can use them to point to _static_ member functions, which may satisify
the OP''s goal.
-dr
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