26 lines
1.5 KiB
XML
26 lines
1.5 KiB
XML
<?xml version="1.0"?>
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<clause number="17.4.2.2" title="Versioning of constants and static readonly fields">
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<paragraph>Constants and readonly fields have different binary versioning semantics. When an expression references a constant, the value of the constant is obtained at compile-time, but when an expression references a readonly field, the value of the field is not obtained until run-time. <example>[Example: Consider an application that consists of two separate programs: <code_example><![CDATA[
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using System;
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namespace Program1
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{
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public class Utils
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{
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public static readonly int X = 1;
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}
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}
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namespace Program2
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{
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class Test
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{
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static void Main() {
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Console.WriteLine(Program1.Utils.X);
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}
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}
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}
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]]></code_example></example></paragraph>
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<paragraph>
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<example>The Program1 and Program2 namespaces denote two programs that are compiled separately. Because Program1.Utils.X is declared as a static readonly field, the value output by the Console.WriteLine statement is not known at compile-time, but rather is obtained at run-time. Thus, if the value of X is changed and Program1 is recompiled, the Console.WriteLine statement will output the new value even if Program2 isn't recompiled. However, had X been a constant, the value of X would have been obtained at the time Program2 was compiled, and would remain unaffected by changes in Program1 until Program2 is recompiled. end example]</example>
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</paragraph>
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</clause>
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