32 lines
1.4 KiB
XML
32 lines
1.4 KiB
XML
<?xml version="1.0"?>
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<clause number="24.1.2" title="Positional and named parameters">
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<paragraph>Attribute classes can have positional parameters and named parameters. Each public instance constructor for an attribute class defines a valid sequence of positional parameters for that attribute class. Each non-static public read-write field and property for an attribute class defines a named parameter for the attribute class. </paragraph>
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<paragraph>
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<example>[Example: The example <code_example><![CDATA[
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using System;
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[AttributeUsage(AttributeTargets.Class)]
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public class HelpAttribute: Attribute
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{
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public HelpAttribute(string url) { // url is a positional parameter
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...
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}
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public string Topic { // Topic is a named parameter
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get {...}
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set {...}
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}
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public string Url { get {...} }
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}
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]]></code_example>defines an attribute class named HelpAttribute that has one positional parameter (string url) and one named parameter (string Topic). Although it is non-static and public, the property Url does not define a named parameter, since it is not read-write. </example>
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</paragraph>
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<paragraph>
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<example>This attribute class might be used as follows: <code_example><![CDATA[
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[Help("http://www.mycompany.com/.../Class1.htm")]
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class Class1 {
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}
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[Help("http://www.mycompany.com/.../Misc.htm", Topic ="Class2")]
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class Class2 {
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}
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]]></code_example>end example]</example>
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</paragraph>
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</clause>
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