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<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="20.1.3.htm"><img src="previous.gif" alt="previous" border="0" /></a><a href="20.2.1.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="20.1.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="20.3.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number">20.2</span><span class="clause-title"> Interface members</span></span><span class="locator">
Paragraph 1</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P1S1"></a>The members of an interface are the members inherited from the base interfaces and the members declared by the interface itself.</span> <span class="grammar-production"><span class="name"><a name="interface-member-declarations"></a>interface-member-declarations</span> : <span class="rhs"><span class="non-terminal"><a href="20.2.htm#interface-member-declaration">interface-member-declaration</a></span> </span><span class="rhs"><span class="non-terminal"><a href="20.2.htm#interface-member-declarations">interface-member-declarations</a></span> <span class="non-terminal"><a href="20.2.htm#interface-member-declaration">interface-member-declaration</a></span> </span></span><span class="grammar-production"><span class="name"><a name="interface-member-declaration"></a>interface-member-declaration</span> : <span class="rhs"><span class="non-terminal"><a href="20.2.1.htm#interface-method-declaration">interface-method-declaration</a></span> </span><span class="rhs"><span class="non-terminal"><a href="20.2.2.htm#interface-property-declaration">interface-property-declaration</a></span> </span><span class="rhs"><span class="non-terminal"><a href="20.2.3.htm#interface-event-declaration">interface-event-declaration</a></span> </span><span class="rhs"><span class="non-terminal"><a href="20.2.4.htm#interface-indexer-declaration">interface-indexer-declaration</a></span> </span></span></span><span class="locator">
Paragraph 2</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P2S1"></a>An interface declaration may declare zero or more members.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P2S2"></a>The members of an interface must be methods, properties, events, or indexers.</span> <span class="sentence"><span class="sentence-number">3</span> <a name="P2S3"></a>An interface cannot contain constants, fields, operators, instance constructors, destructors, or types, nor can an interface contain static members of any kind.</span> </span><span class="locator">
Paragraph 3</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P3S1"></a>All interface members implicitly have public access.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P3S2"></a>It is a compile-time error for interface member declarations to include any modifiers.</span> <span class="sentence"><span class="sentence-number">3</span> <a name="P3S3"></a>In particular, interface members cannot be declared with the modifiers abstract, public, protected, internal, private, virtual, override, or static.</span> </span><span class="paragraph"><span class="example">[Example: The example <pre class="code-example">
public delegate void StringListEvent(IStringList sender);
public interface IStringList
{
void Add(string s);
int Count { get; }
event StringListEvent Changed;
string this[int index] { get; set; }
}
</pre>declares an interface that contains one each of the possible kinds of members: A method, a property, an event, and an indexer. 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>An <span class="non-terminal"><a href="20.1.htm#interface-declaration">interface-declaration</a></span> creates a new declaration space (<a href="10.3.htm">§10.3</a>), and the <span class="non-terminal"><a href="20.2.htm#interface-member-declaration">interface-member-declaration</a></span>s immediately contained by the <span class="non-terminal"><a href="20.1.htm#interface-declaration">interface-declaration</a></span> introduce new members into this declaration space.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P4S2"></a>The following rules apply to interface-member-declarations: </span><ul><li><span class="sentence"><span class="sentence-number">3</span> <a name="P4S3"></a> The name of a method must differ from the names of all properties and events declared in the same interface.</span> <span class="sentence"><span class="sentence-number">4</span> <a name="P4S4"></a>In addition, the signature (<a href="10.6.htm">§10.6</a>) of a method must differ from the signatures of all other methods declared in the same interface.</span> </li><li><span class="sentence"><span class="sentence-number">5</span> <a name="P4S5"></a> The name of a property or event must differ from the names of all other members declared in the same interface.</span> </li><li><span class="sentence"><span class="sentence-number">6</span> <a name="P4S6"></a> The signature of an indexer must differ from the signatures of all other indexers declared in the same interface.</span> </li></ul></span><span class="locator">
Paragraph 5</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P5S1"></a>The inherited members of an interface are specifically not part of the declaration space of the interface.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P5S2"></a>Thus, an interface is allowed to declare a member with the same name or signature as an inherited member.</span> <span class="sentence"><span class="sentence-number">3</span> <a name="P5S3"></a>When this occurs, the derived interface member is said to hide the base interface member.</span> <span class="sentence"><span class="sentence-number">4</span> <a name="P5S4"></a>Hiding an inherited member is not considered an error, but it does cause the compiler to issue a warning.</span> <span class="sentence"><span class="sentence-number">5</span> <a name="P5S5"></a>To suppress the warning, the declaration of the derived interface member must include a new modifier to indicate that the derived member is intended to hide the base member.</span> <span class="sentence"><span class="sentence-number">6</span> <a name="P5S6"></a>This topic is discussed further in <a href="10.7.1.2.htm">§10.7.1.2</a>.</span> </span><span class="locator">
Paragraph 6</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P6S1"></a>If a new modifier is included in a declaration that doesn't hide an inherited member, a warning is issued to that effect.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P6S2"></a>This warning is suppressed by removing the new modifier.</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
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