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make implicit cast of tagged unions to enums easier to find in docs

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xackus 2019-10-27 21:35:22 +01:00
parent a0abd3be85
commit 8960e8090e
1 changed files with 9 additions and 0 deletions
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doc/langref.html.in
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@ -2778,6 +2778,7 @@ test "simple union" {
This turns the union into a <em>tagged</em> union, which makes it eligible
to use with {#link|switch#} expressions. One can use {#link|@TagType#} to
obtain the enum type from the union type.
Tagged unions implicitly cast to their enum {#link|Implicit Cast: unions and enums#}
</p>
{#code_begin|test#}
const std = @import("std");
@ -2805,6 +2806,14 @@ test "switch on tagged union" {
test "@TagType" {
assert(@TagType(ComplexType) == ComplexTypeTag);
}
test "implicit cast to enum" {
const c1 = ComplexType{ .Ok = 42 };
const c2 = ComplexType.NotOk;
assert(c1 == .Ok);
assert(c2 == .NotOk);
}
{#code_end#}
<p>In order to modify the payload of a tagged union in a switch expression,
place a {#syntax#}*{#endsyntax#} before the variable name to make it a pointer: