风格问题 [英] a question of style
问题描述
如果我有添加将指向foo的指针添加到私有
std :: list的方法，我应该定义添加类似
1. void add（const foo& f）{lst.push_back（& f）; $
保持指针不在我的界面之内，或者我应该隐含一个
指针被添加到列表中，就像这样
2. void add（foo * f）{lst.push_back（f）; }
第一种方法是否会引导用户相信他们的foo实际上是存储的b $ b，这可能会导致列表中的内存值不佳
foo被破坏了吗？或者，只要我使用pre和
的帖子条件，这个讨论就没有用了吗？
Tim Partridge
" Tim Partridge" < TJ ****** @ lassar.math.uwaterloo.ca>写道...如果我有一个添加将指向foo的指针添加到私有
std :: list的方法，我应该定义添加类似
1. void add（const foo& f）{lst.push_back（& ;F ）; }
保持我的界面指针，
肯定不是。这允许在添加的调用中使用''foo''
类型的临时值，并且你不想存储指向任何
的指针列表中的临时工具。
或者我应该隐含一个
指针被添加到列表中，就像这样
2. void add（foo * f）{lst.push_back（f）; }
是的，这是票。你当然可以使用引用
非const''foo''：
void add（foo& f）{lst.push_back（ &安培; F）; }
这比第一个好一点，因为它不会让呼叫者暂时使用
。
第一种方法会引导用户相信他们的foo实际上是存储的，一旦foo被破坏，可能会导致列表中的内存值不好吗？
是的。
或者只要我使用pre和
发布条件，这个讨论是否没什么问题？
我想这取决于你如何设置条件和
验证。
Victor
Tim Partridge写道：
如果我有一个添加将指向foo的指针添加到私有
std :: list的方法，我应该定义添加类似
1. void add（const foo& f）{lst.push_back（& ;F ）; }
保持指针不在我的界面，或者我应该隐含一个
指针被添加到列表中，如此
2. void add（foo * f）{lst.push_back（f）;第一种方法会引导用户相信他们的foo实际上是存储的，一旦foo被破坏，可能会导致列表中的内存值不好吗？或者，只要我使用pre和
发布条件，这个讨论就没有意义吗？
这是一个技术问题。答案是选择较弱的东西，而不是更强大的东西。除非你需要一个指针的额外功能，否则更喜欢引用。
接口的唯一区别是指针可能是NULL。
你能推动一个NULL？
另一个答案是symetry。当然，''get''或''pop''方法应该返回相同类型的
。他们可以返回NULL，例如对于未找到
的情况吗？
最后，你应该避免列表拥有对象的暗示或者
一个人无法登记堆栈对象。
-
Phlip
http://www.c2.com/cgi/wiki?TestFirstUserInterfaces
If I have an "add" method that adds a pointer to a foo to a private
std::list, should I define add like
1. void add( const foo &f ) { lst.push_back( &f ); }
to keep pointers out of my interface, or should I make it implicit that a
pointer is being added to the list, like so
2. void add( foo *f ) { lst.push_back( f ); }
Would the first method lead the user to believe that their foo is actually
being stored, potentially leading to a bad memory value in the list once
the foo is destroyed? Or is this discussion moot as long as I use pre and
post conditions?
Tim Partridge
解决方案"Tim Partridge" <tj******@lassar.math.uwaterloo.ca> wrote...If I have an "add" method that adds a pointer to a foo to a private
std::list, should I define add like
1. void add( const foo &f ) { lst.push_back( &f ); }
to keep pointers out of my interface,
Most certainly not. This allows to use temporaries of type ''foo''
in a call to ''add'', and you don''t want to store pointers to any
temporaries in your list.
or should I make it implicit that a
pointer is being added to the list, like so
2. void add( foo *f ) { lst.push_back( f ); }
Yes, that''s the ticket. You could of course, use a reference to
non-const ''foo'':
void add(foo& f) { lst.push_back(&f); }
which is a tad better than the first one because it won''t let
the caller to use a temporary.
Would the first method lead the user to believe that their foo is actually
being stored, potentially leading to a bad memory value in the list once
the foo is destroyed?
Yes.
Or is this discussion moot as long as I use pre and
post conditions?
I suppose it depends on how you set up your conditions and their
verification.
Victor
Tim Partridge wrote:
If I have an "add" method that adds a pointer to a foo to a private
std::list, should I define add like
1. void add( const foo &f ) { lst.push_back( &f ); }
to keep pointers out of my interface, or should I make it implicit that a
pointer is being added to the list, like so
2. void add( foo *f ) { lst.push_back( f ); }
Would the first method lead the user to believe that their foo is actually
being stored, potentially leading to a bad memory value in the list once
the foo is destroyed? Or is this discussion moot as long as I use pre and
post conditions?
This is a technical question. The answer is to prefer weaker things to
stronger ones. Prefer references unless you need a pointer''s extra features.
The only difference at an interface is the pointer could be NULL.
Can you push a NULL?
Another answer is symetry. The ''get'' or ''pop'' methods should, of course,
return the same type. Can they return a NULL, such as for a "not found"
situation?
Finally, you should avoid the implication that the list owns the object, or
that one can''t enlist stack objects.
--
Phlip
http://www.c2.com/cgi/wiki?TestFirstUserInterfaces
Tim Partridge
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