[go] math: implement Abs function using generics
Gerrit Bot (Gerrit)
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math: implement Abs function using generics
Enabling the following list of numeric types:
- ~int,
- ~int8,
- ~int16,
- ~int32,
- ~int64,
- ~float32,
- ~float64
The existing implementation for Abs is optimized for float64 arguments.
This commit adds generic parameter to the Abs function after verifying
that it does not degrade performance
The investigation for this change is described at
https://github.com/golang/go/issues/55929
Fixes #55929
Change-Id: Id8824a5dbddc97a8f3669c1676961214c4622772
GitHub-Last-Rev: 6a152504797828bf6939102f7d4d3f21a768e816
GitHub-Pull-Request: golang/go#55931
---
M src/math/abs.go
M src/math/example_test.go
2 files changed, 59 insertions(+), 8 deletions(-)
diff --git a/src/math/abs.go b/src/math/abs.go
index 08be145..a314d64 100644
--- a/src/math/abs.go
+++ b/src/math/abs.go
@@ -10,6 +10,10 @@
//
// Abs(±Inf) = +Inf
// Abs(NaN) = NaN
-func Abs(x float64) float64 {
- return Float64frombits(Float64bits(x) &^ (1 << 63))
+type number interface {
+ ~int | ~int8 | ~int16 | ~int32 | ~int64 | ~float32 | ~float64
+}
+
+func Abs[T number](x T) T {
+ return T(Float64frombits(Float64bits(float64(x)) &^ (1 << 63)))
}
diff --git a/src/math/example_test.go b/src/math/example_test.go
index a26d8cb..621d7d6 100644
--- a/src/math/example_test.go
+++ b/src/math/example_test.go
@@ -174,14 +174,32 @@
}
func ExampleAbs() {
- x := math.Abs(-2)
- fmt.Printf("%.1f\n", x)
+ xFloat64 := math.Abs(float64(-2))
+ fmt.Printf("%.1f, %T\n", xFloat64, xFloat64)
- y := math.Abs(2)
- fmt.Printf("%.1f\n", y)
+ yFloat64 := math.Abs(float64(2))
+ fmt.Printf("%.1f, %T\n", yFloat64, yFloat64)
+
+ xInt := math.Abs(int(-2))
+ fmt.Printf("%d, %T\n", xInt, xInt)
+
+ yInt := math.Abs(int(2))
+ fmt.Printf("%d, %T\n", yInt, yInt)
+
+ type int64Type int64
+ xTypeInt64 := math.Abs(int64Type(-2))
+ fmt.Printf("%d, %T\n", xTypeInt64, xTypeInt64)
+
+ yTypeInt64 := math.Abs(int64Type(2))
+ fmt.Printf("%d, %T\n", yTypeInt64, yTypeInt64)
+
// Output:
- // 2.0
- // 2.0
+ // 2.0, float64
+ // 2.0, float64
+ // 2, int
+ // 2, int
+ // 2, math_test.int64Type
+ // 2, math_test.int64Type
}
func ExampleDim() {
fmt.Printf("%.2f\n", math.Dim(4, -2))
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Gopher Robot (Gerrit)
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Rob Pike (Gerrit)
Attention is currently required from: Robert Griesemer, Russ Cox.
Patch set 1:Hold +1
Rob Pike (Gerrit)
Attention is currently required from: Robert Griesemer, Russ Cox.
1 comment:
Patchset:
The proposal was declined, so this will not happen as written here.
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Gopher Robot (Gerrit)
Gopher Robot abandoned this change![]( "Open in Gerrit")
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