📄 20.4.3.htm
字号:
<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>Hyperlinked ECMA C# Language Specification</title><meta name="author" content="Jon Jagger" /><link rel="stylesheet" href="ecma334.css"></link></head><body><div align="right"><em><a href="http://www.jaggersoft.com">Jon Jagger</a></em></div><div align="right"><a href="mailto:jon@jaggersoft.com">jon@jaggersoft.com</a></div><form method="get" action="http://search.atomz.com/search/"><input size="30" name="sp-q"></input><input type="submit" value="Search C# Spec"></input><input type="hidden" name="sp-a" value="sp10024177"></input><input type="hidden" name="sp-f" value="ISO-8859-1"></input></form><a href="toc.htm">Table of Contents</a> <a href="1.htm">1</a> <a href="2.htm">2</a> <a href="3.htm">3</a> <a href="4.htm">4</a> <a href="5.htm">5</a> <a href="6.htm">6</a> <a href="7.htm">7</a> <a href="8.htm">8</a> <a href="9.htm">9</a> <a href="10.htm">10</a> <a href="11.htm">11</a> <a href="12.htm">12</a> <a href="13.htm">13</a> <a href="14.htm">14</a> <a href="15.htm">15</a> <a href="16.htm">16</a> <a href="17.htm">17</a> <a href="18.htm">18</a> <a href="19.htm">19</a> <a href="20.htm">20</a> <a href="21.htm">21</a> <a href="22.htm">22</a> <a href="23.htm">23</a> <a href="24.htm">24</a> <a href="25.htm">25</a> <a href="notes.htm">Notes</a> <a href="HyperlinkedCSharpECMA.zip">Download</a><span class="ruler"></span><span class="heading">ECMA-334 C# Language Specification</span><span class="navigate"><a href="20.4.2.htm"><img src="previous.gif" alt="previous" border="0" /></a><a href="20.4.4.htm"><img src="next.gif" alt="next" border="0" /></a></span><span class="clause-depth"><a href="19.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="21.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number-link"><a href="20.htm">20</a></span><span class="clause-title-previous"> Interfaces</span></span><span class="clause-depth"><a href="20.3.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="20.4.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number-link"><a href="20.4.htm">20.4</a></span><span class="clause-title-previous"> Interface implementations</span></span><span class="clause-depth"><a href="20.4.2.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="20.4.4.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number">20.4.3</span><span class="clause-title"> Interface implementation inheritance</span></span><span class="locator">
Paragraph 1</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P1S1"></a>A class inherits all interface implementations provided by its base classes.</span> </span><span class="locator">
Paragraph 2</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P2S1"></a>Without explicitly re-implementing an interface, a derived class cannot in any way alter the interface mappings it inherits from its base classes.</span> <span class="example">[Example: For example, in the declarations <pre class="code-example">
interface IControl
{
void Paint();
}
class Control: IControl
{
public void Paint() {...}
}
class TextBox: Control
{
new public void Paint() {...}
}
</pre>the Paint method in TextBox hides the Paint method in Control, but it does not alter the mapping of Control.Paint onto IControl.Paint, and calls to Paint through class instances and interface instances will have the following effects <pre class="code-example">
Control c = new Control();
TextBox t = new TextBox();
IControl ic = c;
IControl it = t;
c.Paint(); // invokes Control.Paint();
t.Paint(); // invokes TextBox.Paint();
ic.Paint(); // invokes Control.Paint();
it.Paint(); // invokes Control.Paint();
</pre>end example]</span> </span><span class="locator">
Paragraph 3</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P3S1"></a>However, when an interface method is mapped onto a virtual method in a class, it is possible for derived classes to override the virtual method and alter the implementation of the interface.</span> <span class="example">[Example: For example, rewriting the declarations above to <pre class="code-example">
interface IControl
{
void Paint();
}
class Control: IControl
{
public virtual void Paint() {...}
}
class TextBox: Control
{
public override void Paint() {...}
}
</pre>the following effects will now be observed <pre class="code-example">
Control c = new Control();
TextBox t = new TextBox();
IControl ic = c;
IControl it = t;
c.Paint(); // invokes Control.Paint();
t.Paint(); // invokes TextBox.Paint();
ic.Paint(); // invokes Control.Paint();
it.Paint(); // invokes TextBox.Paint();
</pre>end example]</span> </span><span class="locator">
Paragraph 4</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P4S1"></a>Since explicit interface member implementations cannot be declared virtual, it is not possible to override an explicit interface member implementation.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P4S2"></a>However, it is perfectly valid for an explicit interface member implementation to call another method, and that other method can be declared virtual to allow derived classes to override it.</span> <span class="example">[Example: For example <pre class="code-example">
interface IControl
{
void Paint();
}
class Control: IControl
{
void IControl.Paint() { PaintControl(); }
protected virtual void PaintControl() {...}
}
class TextBox: Control
{
protected override void PaintControl() {...}
}
</pre></span></span><span class="paragraph"><span class="example">Here, classes derived from Control can specialize the implementation of IControl.Paint by overriding the PaintControl method. end example]</span> </span><span class="ruler"></span><table><tr><td><table align="left" bgcolor="navy"><tr bgcolor="navy"><td><font face="Arial,sans-serif" size="6" color="yellow"><strong>{ JSL }</strong></font></td></tr></table></td></tr><tr><td><font face="Arial,sans-serif" size="2" color="navy"><strong>Jagger Software Ltd</strong></font></td></tr><tr><td><font face="Arial,sans-serif" size="2" color="navy"><strong>Company # 4070126</strong></font></td></tr><tr><td><font face="Arial,sans-serif" size="2" color="navy"><strong>VAT # 762 5213 42</strong></font></td></tr></table><img src="valid-html401.png" align="left" height="31" width="88" alt="Valid HTML 4.01" /><img src="vcss.gif" align="left" height="31" width="88" alt="Valid CSS" /></body></html>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -