singleton ienumerable，需要添加更多... [英] singleton ienumerable, need to add more...
问题描述
大家好，
我有一个可以从数据库中收集数据的单件ienumerable。我有
列出下面的代码。它有通常的电流，移动和重置方法。
我需要去某个位置或设置过滤器或许多其他东西我
don我不知道该怎么做。我刚刚学会了单身和无数，所以
奇迹般地让这个到目前为止工作。我可以用一些帮助来进一步使用它来获得
。如果需要，我可能需要更改类型以实现
目标。
我接下来要做的是通过传递选择特定行在索引中。我不知道如何做到这一点，无论我尝试什么，我都不能...... / b
编译。
我的来源如下......
所有帮助表示赞赏。
公共类文件夹：System.Collections.IEnumerable，
System.Collections.IEnumerator
{
private static Folders mObj; //这用于管理单例。
私有DataTable DT;
System.Collections.IEnumerator ienum;
//这是单身构造函数
私人文件夹（）
{
InitData（）;
}
//设置单例。
公共静态文件夹SiteFolders
{
get
{
if（mObj == null）//只创建一个实例
mObj = new文件夹（）;
返回mObj;
}
}
private void InitData（）
{
//从数据库中获取数据并传入ienum
ienum = DT.Rows.GetEnumerator（）;
}
public System.Collections.IEnumerator GetEnumerator（）
{
//将此对象变形为IEnumerator接口
return（System.Collections.IEnumerator）this;
}
公共voi d重置（）
{
ienum.Reset（）;
}
公共布尔MoveNext（）
{
返回ienum.MoveNext（）;
}
公共对象当前
{
get
{
返回新文件夹（（DataRow）ienum.Current）;
}
}
#endregion
公共对象SelectFolder（int myRow）
{
//获取
// {
返回新文件夹（（DataRow）myRow）;
//}
}
}
我也试过使用方括号作为选择文件夹，但只是
不会编译。如何选择特定行？顺便提一下，选择文件夹引用的文件夹
只需要我的数据表并将其传递给
一些属性。
因为我有刚刚了解了单身和无数，我真的这么做了。不知道怎么继续。 ： - （
祝你好运，
Dave Colliver。
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - 提供本地特许经营权
好的，一次一件事。
我认为您正在寻找的索引器语法是：
public这个[ int rowIndex]
{
get
{
返回新文件夹（DT.Rows [rowIndex]）;
}
}
然后你就可以访问Folders.SiteFolders [4];（等等）
请注意，我调整了返回类型是有用的。但是，更大的
积分：
*这是不寻常的可枚举和枚举;我
怀疑你只是意味着IEnumerable或IEnumerable<文件夹>
* T hread安全性：因为你看来是C＃的新手，这可能不会是一个
问题，但一般情况下静态方法应该是线程安全的，这是
SiteFolders isn'' t $ / b $ b *可以放弃获得的普查员，而不是
smoke''n''mirrors？
*每次调用Current返回一个不同的对象;这可能会变得非常，非常令人困惑，并导致各种乐趣
*次要评论问题：这只是一个演员，而不是多态？
*不确定这是否真的适合单身人士模式 - 虽然这可能只是因为我对背景知之甚少，所以我会给予
你怀疑的好处
鉴于你似乎有一个包装器对象（文件夹），可能会有很多好处吗？移动到List< Folderimplementation;这将是
允许你在没有大惊小怪的情况下移交一个简单的枚举器，并且
你的Folder对象只会存在一次 - 你只需要循环遍历
DataTable。
如果您需要更多帮助，请告诉我。
Marc
谢谢Marc，
我在网上找到的最初的可枚举信息，以及
单身人士。 />
我已经做了很多让他们两个都工作的战斗，
我的背景是经典ASP，已经进入.net几年了以前，
但我的知识仍然存在很大的差距。
我尝试过类似公共文件夹这个[int rowIndex]，但保留了
收到错误。但是，我不认为我有这个。字。我会试试。
对于你的积分......
1.我假设这是由该类派生的两个项目。我可以
只是删除IEnumerable它会起作用吗？
2.目前，线程安全不是问题，但很可能是
项目进展。我应该如何写它才能安全？
3.（通过已故的调查员）你能给我一些指示吗？代码
示例或URL？
4.再次，这只是被复制了。据我所知，一个不可数项必须有3个项目中的最少
。 reset，movenext和current。我应该在这做什么？
5. polymorph ...这是一个直接副本。虽然没有涵盖多态，但我不能真的质疑这个，虽然我可以非常清楚地看到（现在你已经提到它了）它是一个演员。 />
6.我在aspnet中有一个24消息线程试图实现这一点。我想要的是一个全球的东西。枚举的数据表。我希望能够只需简单地分配一个变量而不需要新的运营商。一个例子......
我想从数据库中加载文件夹。我不希望每次都要进入数据库，因为数据库调用很昂贵。
我想要所有的控件，Page，UserControls和自定义控件能够
来调用相同的数据实例。拥有新字样运算符每次都会实例化数据
，从而每次都调用数据库。如果您熟悉Microsoft CMS，我想做类似的事情......
频道MyChannels = CmsHttpContext.Current.Channel.Channels;
foeach（MyChannels中的频道ch）
{
Response.Write ch.DisplayName;
}
WantedChannel = MyChannels.Channel.GetByGuid（guid-string）;
注意，不要新。
谢谢。
问候，
Dave Colliver。
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - 门户网站特许经营权
Marc Gravell ;写道：
好的，一次一件事。
我认为索引器你正在寻找的语法是：
公共文件夹这个[int rowIndex]
{
get
{
返回新文件夹（DT.Rows [rowIndex]）;
}
}
然后你可以访问Folders.SiteFolders [4]; （等）
请注意，我调整了返回类型是有用的。然而，更大的
积分：
*对于可枚举的东西和一个枚举器来说是不寻常的;我怀疑你只是意味着IEnumerable或IEnumerable<文件夹>
*线程安全：因为你看起来很新C＃这可能不会是一个
问题，但一般情况下静态方法应该是线程安全的，
SiteFolders不是
*可以直接传递获得的枚举数，而不是< br $> b $ b smoke''n''mirrors？
*每次调用Current都会返回一个不同的对象;这可能会变得非常，非常令人困惑，并导致各种乐趣
*次要评论问题：这只是一个演员，而不是多态？
*不确定这是否真的适合单身人士模式 - 虽然这可能只是因为我对背景知之甚少，所以我会给予
你怀疑的好处
鉴于你似乎有一个包装器对象（文件夹），可能会有很多好处吗？移动到List< Folderimplementation;这将是
允许你在没有大惊小怪的情况下移交一个简单的枚举器，并且
你的Folder对象只会存在一次 - 你只需要循环遍历
DataTable。
如果您需要更多帮助，请告诉我们。
Marc
谢谢Marc，
我在网上找到的最初的可枚举信息，以及
singleton。
我为了让他们两个都工作而进行了相当大的战斗，
我的背景是经典的ASP，有几年前进入.net，
但我的知识仍然存在很大的差距。
我尝试过类似于公共文件夹的东西[此int rowIndex]但保持
得到错误。但是，我不认为我有这个。字。我会试试。
对于你的积分......
1.我假设这是由该类派生的两个项目。我可以
只是删除IEnumerable它会起作用吗？
2.目前，线程安全不是问题，但很可能是
项目进展。我应该如何写它才能安全？
3.（通过已故的调查员）你能给我一些指示吗？代码
示例或URL？
4.再次，这只是被复制了。据我所知，一个不可数项必须有3个项目中的最少
。 reset，movenext和current。我应该在这做什么？
5. polymorph ...这是一个直接副本。虽然没有涵盖多态，但我不能真的质疑这个，虽然我可以非常清楚地看到（现在你已经提到它了）它是一个演员。 />
6.我在aspnet中有一个24消息线程试图实现这一点。我想要的是一个全球的东西。枚举的数据表。我希望能够只需简单地分配一个变量而不需要新的运营商。一个例子......
我想从数据库中加载文件夹。我不希望每次都要进入数据库，因为数据库调用很昂贵。
我想要所有的控件，Page，UserControls和自定义控件能够
来调用相同的数据实例。拥有新字样运算符每次都会实例化数据
，从而每次都调用数据库。如果您熟悉Microsoft CMS，我想做类似的事情......
频道MyChannels = CmsHttpContext.Current.Channel.Channels;
foeach（MyChannels中的频道ch）
{
Response.Write ch.DisplayName;
}
WantedChannel = MyChannels.Channel.GetByGuid（guid-string）;
注意，不要新。
谢谢。
问候，
Dave Colliver。
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - 门户网站特许经营权
Marc Gravell ;写道：
好的，一次一件事。
我认为索引器你正在寻找的语法是：
公共文件夹这个[int rowIndex]
{
get
{
返回新文件夹（DT.Rows [rowIndex]）;
}
}
然后你可以访问Folders.SiteFolders [4]; （等）
请注意，我调整了返回类型是有用的。然而，更大的
积分：
*对于可枚举的东西和一个枚举器来说是不寻常的;我怀疑你只是意味着IEnumerable或IEnumerable<文件夹>
*线程安全：因为你看起来很新C＃这可能不会是一个
问题，但一般情况下静态方法应该是线程安全的，
SiteFolders不是
*可以直接传递获得的枚举数，而不是< br $> b $ b smoke''n''mirrors？
*每次调用Current都会返回一个不同的对象;这可能会变得非常，非常令人困惑，并导致各种乐趣
*次要评论问题：这只是一个演员，而不是多态？
*不确定这是否真的适合单身人士模式 - 虽然这可能只是因为我对背景知之甚少，所以我会给予
你怀疑的好处
鉴于你似乎有一个包装器对象（文件夹），可能会有很多好处吗？移动到List< Folderimplementation;这将是
允许你在没有大惊小怪的情况下移交一个简单的枚举器，并且
你的Folder对象只会存在一次 - 你只需要循环遍历
DataTable。
如果您需要更多帮助，请告诉我们。
Marc
Hi all,
I have a singleton ienumerable that collects data from a database. I have
listed the code below. It has the usual methods of current, move and reset.
I need to go to a certain position or set filters or many other things and I
don''t know how to do this. I have just learned singleton AND ienumerable, so
miraculously got this to work so far. I could do with a bit of help to go
further with it. If need by, I may have to change the type to achieve the
aim.
What I want to do next is to select a specific row by passing in an index. I
don''t know how to do this at all and no matter what I try, I just can''t
compile.
My source is below...
All help is appreciated.
public class Folders : System.Collections.IEnumerable,
System.Collections.IEnumerator
{
private static Folders mObj; // This is used to manage the singleton.
private DataTable DT;
System.Collections.IEnumerator ienum;
// This is the singleton constructor
private Folders()
{
InitData();
}
// This sets up the singleton.
public static Folders SiteFolders
{
get
{
if(mObj == null) // only one instance is created
mObj = new Folders();
return mObj;
}
}
private void InitData()
{
// Get my data from the database and pass into ienum
ienum = DT.Rows.GetEnumerator();
}
public System.Collections.IEnumerator GetEnumerator()
{
// Polymorph this object into an IEnumerator interface
return (System.Collections.IEnumerator)this;
}
public void Reset()
{
ienum.Reset();
}
public bool MoveNext()
{
return ienum.MoveNext();
}
public object Current
{
get
{
return new Folder((DataRow)ienum.Current);
}
}
#endregion
public object SelectFolder(int myRow)
{
// get
// {
return new Folder((DataRow)myRow);
// }
}
}
I have tried using square brackets for the selectfolder as well, but just
won''t compile. How can I select a specific row? Incidentally, the Folder
that selectfolder is referencing just takes my datatable and passes it into
some properties.
Because I have just learned about the singleton and ienumerable, I really do
not know how to continue. :-(
Best regards,
Dave Colliver.
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - Local franchises available
OK, one thing at a time.
I think the "indexer" syntax you are looking for is:
public Folder this[int rowIndex]
{
get
{
return new Folder(DT.Rows[rowIndex]);
}
}
you can then access Folders.SiteFolders[4]; (etc)
Note that I tweaked the return type to be useful. However, the bigger
points:
* it is unusual for something to be enumerable and an enumerator; I
suspect you just mean IEnumerable or IEnumerable<Folder>
* Thread safety: since you appear new to C# this probably won''t be an
issue, but in general static methods should be thread safe, which
SiteFolders isn''t
* could just pass up the obtained enumerator, rather than the
smoke''n''mirrors?
* each call to Current returns a different object; this could get very,
very confusing, and lead to all sorts of fun
* minor comment issue: this is merely a cast, not polymorphism
* not sure this is really suited to a singleton pattern - although that
might just be that I don''t know enough about the context, so I''ll give
you the benefit of the doubt
Given that you seem to have a wrapper object (Folder), there may be a
lot of benefit in moving to a List<Folderimplementation; this would
allow you to hand over a simple enumerator without all the fuss, and
your Folder objects would only exist once each- you''d just loop over
the DataTable.
Let me know if you want more help,
Marc
Thank you Marc,
The initial enumerable info I found on the net somewhere, as also the
singleton.
I have had quite a battle to get them both to work,
My background is classic ASP, having moved into .net a couple of years ago,
but still having large gaps in my knowledge.
I did try something similar to the public Folder this[int rowIndex] but kept
getting errors. However, I don''t think I had the "this" word. I will try that.
For your points...
1. I assume this is with the two items that the class is derived from. Can I
just remove the IEnumerable and it will work?
2. At the moment, thread safety is not an issue, but is likely to be as the
project progresses. How should I write it to be safe?
3. (Pass the obtoned enumerator) Can you give me some pointers? code
examples or URLs?
4. Again, this was just copied. I understand that an ienumerable has to have
a min of 3 items. reset, movenext and current. What should I be doing here?
5. polymorph... This is a direct copy. Having not covered polymorphing, I
couldn''t really question this, though I can quite clearly see (now you
mention it) that it is a cast.
6. I have had a 24 message thread in aspnet trying to acheive this. What I
am wanting is a "global" datatable that is enumerated. I want to be able to
just simply assign a variable without having the "new" operator. An example...
I wanted to have the folders loaded from the database. I DID NOT want to
have to go to the database every time, as a DB call is expensive.
I wanted all my controls, Page, UserControls and Custom Controls to be able
to call the same instance of data. Having a "new" operator would instantiate
the data each time, thereby calling the database each time. If you are
familiar with Microsoft CMS, I want to do something like...
Channels MyChannels = CmsHttpContext.Current.Channel.Channels;
foeach (Channel ch in MyChannels)
{
Response.Write ch.DisplayName;
}
WantedChannel = MyChannels.Channel.GetByGuid("guid-string");
Notice, no "new".
Thank you.
Regards,
Dave Colliver.
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - Portal franchises available
"Marc Gravell" wrote:
OK, one thing at a time.
I think the "indexer" syntax you are looking for is:
public Folder this[int rowIndex]
{
get
{
return new Folder(DT.Rows[rowIndex]);
}
}
you can then access Folders.SiteFolders[4]; (etc)
Note that I tweaked the return type to be useful. However, the bigger
points:
* it is unusual for something to be enumerable and an enumerator; I
suspect you just mean IEnumerable or IEnumerable<Folder>
* Thread safety: since you appear new to C# this probably won''t be an
issue, but in general static methods should be thread safe, which
SiteFolders isn''t
* could just pass up the obtained enumerator, rather than the
smoke''n''mirrors?
* each call to Current returns a different object; this could get very,
very confusing, and lead to all sorts of fun
* minor comment issue: this is merely a cast, not polymorphism
* not sure this is really suited to a singleton pattern - although that
might just be that I don''t know enough about the context, so I''ll give
you the benefit of the doubt
Given that you seem to have a wrapper object (Folder), there may be a
lot of benefit in moving to a List<Folderimplementation; this would
allow you to hand over a simple enumerator without all the fuss, and
your Folder objects would only exist once each- you''d just loop over
the DataTable.
Let me know if you want more help,
Marc
Thank you Marc,
The initial enumerable info I found on the net somewhere, as also the
singleton.
I have had quite a battle to get them both to work,
My background is classic ASP, having moved into .net a couple of years ago,
but still having large gaps in my knowledge.
I did try something similar to the public Folder this[int rowIndex] but kept
getting errors. However, I don''t think I had the "this" word. I will try that.
For your points...
1. I assume this is with the two items that the class is derived from. Can I
just remove the IEnumerable and it will work?
2. At the moment, thread safety is not an issue, but is likely to be as the
project progresses. How should I write it to be safe?
3. (Pass the obtoned enumerator) Can you give me some pointers? code
examples or URLs?
4. Again, this was just copied. I understand that an ienumerable has to have
a min of 3 items. reset, movenext and current. What should I be doing here?
5. polymorph... This is a direct copy. Having not covered polymorphing, I
couldn''t really question this, though I can quite clearly see (now you
mention it) that it is a cast.
6. I have had a 24 message thread in aspnet trying to acheive this. What I
am wanting is a "global" datatable that is enumerated. I want to be able to
just simply assign a variable without having the "new" operator. An example...
I wanted to have the folders loaded from the database. I DID NOT want to
have to go to the database every time, as a DB call is expensive.
I wanted all my controls, Page, UserControls and Custom Controls to be able
to call the same instance of data. Having a "new" operator would instantiate
the data each time, thereby calling the database each time. If you are
familiar with Microsoft CMS, I want to do something like...
Channels MyChannels = CmsHttpContext.Current.Channel.Channels;
foeach (Channel ch in MyChannels)
{
Response.Write ch.DisplayName;
}
WantedChannel = MyChannels.Channel.GetByGuid("guid-string");
Notice, no "new".
Thank you.
Regards,
Dave Colliver.
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - Portal franchises available
"Marc Gravell" wrote:
OK, one thing at a time.
I think the "indexer" syntax you are looking for is:
public Folder this[int rowIndex]
{
get
{
return new Folder(DT.Rows[rowIndex]);
}
}
you can then access Folders.SiteFolders[4]; (etc)
Note that I tweaked the return type to be useful. However, the bigger
points:
* it is unusual for something to be enumerable and an enumerator; I
suspect you just mean IEnumerable or IEnumerable<Folder>
* Thread safety: since you appear new to C# this probably won''t be an
issue, but in general static methods should be thread safe, which
SiteFolders isn''t
* could just pass up the obtained enumerator, rather than the
smoke''n''mirrors?
* each call to Current returns a different object; this could get very,
very confusing, and lead to all sorts of fun
* minor comment issue: this is merely a cast, not polymorphism
* not sure this is really suited to a singleton pattern - although that
might just be that I don''t know enough about the context, so I''ll give
you the benefit of the doubt
Given that you seem to have a wrapper object (Folder), there may be a
lot of benefit in moving to a List<Folderimplementation; this would
allow you to hand over a simple enumerator without all the fuss, and
your Folder objects would only exist once each- you''d just loop over
the DataTable.
Let me know if you want more help,
Marc
这篇关于singleton ienumerable，需要添加更多...的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
