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Merge pull request #18219 from g-cassie/optional-documentation-tweaks

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Minor improvements to the Optionals documentation
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Andrew Kelley 2024-01-18 20:34:00 -08:00 • committed by GitHub
commit 9b714e019c
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1 changed files with 58 additions and 40 deletions
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98
doc/langref.html.in
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@ -4640,6 +4640,7 @@ test "while null capture" {
}
try expect(sum1 == 3);
// null capture with an else block
var sum2: u32 = 0;
numbers_left = 3;
while (eventuallyNullSequence()) |value| {
@ -4647,6 +4648,15 @@ test "while null capture" {
} else {
try expect(sum2 == 3);
}
// null capture with a continue expression
var i: u32 = 0;
var sum3: u32 = 0;
numbers_left = 3;
while (eventuallyNullSequence()) |value| : (i += 1) {
sum3 += value;
}
try expect(i == 3);
}
var numbers_left: u32 = undefined;
@ -4927,46 +4937,6 @@ test "if boolean" {
}
}
test "if optional" {
// If expressions test for null.
const a: ?u32 = 0;
if (a) |value| {
try expect(value == 0);
} else {
unreachable;
}
const b: ?u32 = null;
if (b) |_| {
unreachable;
} else {
try expect(true);
}
// The else is not required.
if (a) |value| {
try expect(value == 0);
}
// To test against null only, use the binary equality operator.
if (b == null) {
try expect(true);
}
// Access the value by reference using a pointer capture.
var c: ?u32 = 3;
if (c) |*value| {
value.* = 2;
}
if (c) |value| {
try expect(value == 2);
} else {
unreachable;
}
}
test "if error union" {
// If expressions test for errors.
// Note the |err| capture on the else.
@ -5011,6 +4981,51 @@ test "if error union" {
unreachable;
}
}
{#code_end#}
{#header_open|if with Optionals#}
{#code_begin|test|test_if_optionals#}
const expect = @import("std").testing.expect;
test "if optional" {
// If expressions test for null.
const a: ?u32 = 0;
if (a) |value| {
try expect(value == 0);
} else {
unreachable;
}
const b: ?u32 = null;
if (b) |_| {
unreachable;
} else {
try expect(true);
}
// The else is not required.
if (a) |value| {
try expect(value == 0);
}
// To test against null only, use the binary equality operator.
if (b == null) {
try expect(true);
}
// Access the value by reference using a pointer capture.
var c: ?u32 = 3;
if (c) |*value| {
value.* = 2;
}
if (c) |value| {
try expect(value == 2);
} else {
unreachable;
}
}
test "if error union with optional" {
// If expressions test for errors before unwrapping optionals.
@ -5056,6 +5071,7 @@ test "if error union with optional" {
}
}
{#code_end#}
{#header_close#}
{#see_also|Optionals|Errors#}
{#header_close#}
{#header_open|defer#}
@ -6379,6 +6395,8 @@ test "optional pointers" {
}
{#code_end#}
{#header_close#}
{#see_also|while with Optionals|if with Optionals#}
{#header_close#}
{#header_open|Casting#}
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