README
¶
safecast
Avoid accidental overflow of numbers during go type conversions (e.g instead of shorter := bigger.(int8) type conversions use shorter := safecast.MustConvert[int8](bigger).
Safecast allows you to safely convert between numeric types in Go and return errors (or panic when using the Must* variants) when the cast would result in a loss of precision, range or sign.
See https://pkg.go.dev/fortio.org/safecast for docs and example. This is usable from any go with generics (1.18 or later) though our CI uses the latest go.
safecast is about avoiding gosec G115 and CWE-190: Integer Overflow or Wraparound class of overflow and loss of precision bugs, extended to float64/float32 issues.
Credit for the idea (and a finding a bug in the first implementation) goes to @ccoVeille, Please see https://github.com/ccoVeille/go-safecast for an different style API and implementation to pick whichever fits your style best.
Documentation
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Overview ¶
Package safecast allows you to safely cast between numeric types in Go and return errors (or panic when using the Must* variants) when the cast would result in a loss of precision, range or sign.
Example ¶
package main
import (
"fmt"
"fortio.org/safecast"
)
func main() {
var in int16 = 256
// will error out
out, err := safecast.Convert[uint8](in)
fmt.Println(out, err)
// will be fine
out = safecast.MustRound[uint8](255.4)
fmt.Println(out)
// Also fine
out = safecast.MustTruncate[uint8](255.6)
fmt.Println(out)
}
Output: 0 out of range 255 255
Index ¶
- Variables
- func Convert[NumOut Number, NumIn Number](orig NumIn) (converted NumOut, err error)
- func MustConvert[NumOut Number, NumIn Number](orig NumIn) NumOut
- func MustRound[NumOut Number, NumIn Float](orig NumIn) NumOut
- func MustTruncate[NumOut Number, NumIn Float](orig NumIn) NumOut
- func Round[NumOut Number, NumIn Float](orig NumIn) (converted NumOut, err error)
- func Truncate[NumOut Number, NumIn Float](orig NumIn) (converted NumOut, err error)
- type Float
- type Integer
- type Number
Examples ¶
Constants ¶
This section is empty.
Variables ¶
var ErrOutOfRange = errors.New("out of range")
Functions ¶
func Convert ¶
Convert converts a number from one type to another, returning an error if the conversion would result in a loss of precision, range or sign (overflow). In other words if the converted number is not equal to the original number. Do not use for identity (same type in and out) but in particular this will error for Convert[uint64](uint64(math.MaxUint64)) because it needs to when converting to any float.
func MustConvert ¶
Same as Convert but panics if there is an error.
func MustRound ¶
Same as Round but panics if there is an error.
Example ¶
package main
import (
"fmt"
"fortio.org/safecast"
)
func main() {
defer func() {
if r := recover(); r != nil {
fmt.Println("panic:", r)
}
}()
out := safecast.MustRound[int8](-128.6)
fmt.Println("not reached", out) // not reached
}
Output: panic: safecast: out of range for -128.6 (float64) to int8
func MustTruncate ¶
Same as Truncate but panics if there is an error.
Source Files