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package໊ͱม໊͕
͔Ϳ͍ͬͯΔͷΛ
ͱʹ͔͘ݕग़͍ͨ͠
golang.tokyo #25 2019-06-18
@mackee_w a.k.a macopy
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Ͳ͏͍͏͜ͱ͔
package main
import (
"os"
"errors"
)
func main() {
// Ҿ͔Β࣮ߦ͢Δ܅ΛऔΓग़͢
runner := NewRunners(os.Args[1:])
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errors := make([]error, 0, len(runner))
for _, r := range runners {
result, err := runner.Run()
if err != nil {
errors = append(errors, err)
}
if result == nil {
errors = append(
errors,
errors.New("result is nil"),
)
}
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1ߦา͍ͨΒΕͯΔ
errors = append(
errors,
errors.New("result is nil"),
)
• વ͜ΕίϯύΠϧ͕௨Βͳ͍
• errorsύοέʔδطʹ͑ͳ͘ͳ͍ͬͯΔͨΊ
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͜ͷίʔυ͕ੜ·ΕΔࢥߟͷաఔ
• errors ͍͍ͨͳΝ(github.com/pkg/errorsͰՄ)
• ͦΕ͓͖ͯ͞errorΛ·ͱΊ͓͖͍͔ͯͨΒerrorsͱ͍͏
มΛએݴ͢Δͧ
• ΞϨϨɺerrors.Newͱ͔errors.Wrapͱ͔ͷิ͕ޮ͔ͳ
͍ͧ
• ͔ͿͬͯΔʂʂʂ
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Έͳ͞ΜͦΜͳܦݧ͋Γ·ͤΜ͔ʁ
• ʮ໋໊͕ྑ͘ͳ͍͔ΒͰʁʯ
• ͜͜·Ͱ͔͋Β͞·ͳ͜ͱͳͯ͘ɺύοέʔδ໊ͱม໊
͕͔Ϳͬͯࠞཚ͢Δ͜ͱ͕͋Γ·͢
• ͪͳΈʹࢲ্هͷΑ͏ͳerrorsΛimport͍ͯ͠Δͷʹ
errorsΛ࡞Γग़͢͜ͱ͕͋Γ·͢(ຊʹ)
• ݪҼ͕ίϯύΠϧΤϥʔͱҧ͏Օॴʹ͋ΔͨΊΘ͔Γʹ͍͘
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ͦͷଞղܾ͍ͨ͠έʔεstruct໊ͱม໊͕͔ͿΔ
type sheet struct {
// ...
}
func NewSheet() *sheet {
return &sheet{}
}
func (s *sheet) String() string {
// ...
}
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ͦͷଞղܾ͍ͨ͠έʔεstruct໊ͱม໊͕͔ͿΔ
ಉ͡ύοέʔδͷҧ͏ϑΝΠϧͰ
func DoSomething() {
sheet := NewSheet()
// ...
}
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͜͏ॻ͔ΕΔͱԿ͕ى͜Δ͔
• ίϯύΠϧ௨Δ
• DoSomethingͷͰsheetΛࣗͰnewग़དྷͳ͍
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ύοέʔδͷ໊લͱԾҾ͕͔ͿΔ
import "path"
func ReadFromFile(path string) error {
//...
}
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͜͏ॻ͔ΕΔͱԿ͕ى͜Δ͔
• ίϯύΠϧ௨Δ
• ReadFromFileͷதͰpathύοέʔδͷ͕ؔݺͳ͘ͳΔ
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ศརͳέʔε͋Δ
Ұ෦ͷείʔϓ͚ͩlogΛผͷͷʹஔ͖͑Δͱ͔(ͦͦ͜͜अѱ
import "log"
// ͜ͷϝιουͷத͚ͩϑΝΠϧʹॻ͘
func Do() {
log := log.New(logfile, "Do(): ", log.LstdFlags)
// ্ͷ1ߦΛՃ͑Δ͚ͩͰଞͷߦॻ͖͑ͳ͍͍ͯ͘
log.Println("print something")
}
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ݴޠ༷͕ѱ͍ͱݴ͍͍ͨΘ͚Ͱͳ͘...
ਓؒϛεΛ͢ΔͷͰ...
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ҙਤ͔ͤͣͿͬͯΔ
έʔεΛݕ͍ͨ͠
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github.com/mackee/conflic1dent
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ྫ
pathύοέʔδͱmainؔείʔϓͷpathม͕͔ͿͬͯΔ
import "path"
func main() {
path := "example.txt"
}
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࣮ߦྫ
ίϚϯυ࣮ߦ͢Δͱ
$ conflictident .
ग़ྗ͜Μͳײ͡
pkgident.go:12:2:
conflict identifier name of 'path' by pkgident.go:4:2.
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ରԠ͍ͯ͠Δ͔Ϳ͍ͬͯΔྫ
• ύοέʔδ໊ͱม໊
• ύοέʔδ໊ͱԾҾ໊
• ಉ͡ύοέʔδͷܕͱม໊/ԾҾ໊
• ಉ͡ύοέʔδͷconstͷ໊લͱม໊/ԾҾ໊
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ͱʹ͔͘ศར...
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ྨࣅ
• golang.org/x/tools/go/analysis/passes/shadow/
cmd/shadow
• มͷshadowingΛݕͯ͘͠ΕΔ
func BadRead(f *os.File, buf []byte) error {
var err error
for {
n, err := f.Read(buf) // shadows the function variable 'err'
if err != nil {
break // causes return of wrong value
}
foo(buf)
}
return err
}
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ຊݴ͍͍ͨͷ
golang.org/x/tools/analysis ͕ศར...
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3ߦͰΘ͔Δx/tools/analysis
• ੩తղੳνΣοΧʔΛ࡞ΔϑϨʔϜϫʔΫతͳϥΠϒϥϦ
• ੩తղੳʹඞཁͳ ಡΉ, ղੳ͢Δ, ग़ྗ͢Δ ͷ͏ͪ ಡΉ, ग़ྗ͢
Δ ΛΑ͠ͳʹͬͯ͘ΕΔ
• ੩తղੳνΣοΧʔͷςετέʔεهड़͕ઈָ
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x/tools/analysisΛ͍ͬͯΔίʔυ
package conflictident
import (
"golang.org/x/tools/go/analysis"
"golang.org/x/tools/go/analysis/passes/inspect"
"golang.org/x/tools/go/ast/inspector"
)
var Analyzer = &analysis.Analyzer{
Name: "conflictident",
Doc: Doc,
Run: run,
Requires: []*analysis.Analyzer{
inspect.Analyzer,
},
}
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x/tools/analysisΛ͍ͬͯΔίʔυ
func run(pass *analysis.Pass) (interface{}, error) {
ins := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
nodeFilter := []ast.Node{
// ͜͜ʹཉ͍͠ASTͷϊʔυೖΕΑ͏
}
ins.WithStack(nodeFilter, func(n ast.Node, push bool, stack []ast.Node) bool {
// ϑΟϧλʹઃఆͨ͠ASTͷϊʔυ͕ͬͯ͘Δͧ ͦΕΛݟ͍͍ͯײ͡ʹग़ྗ͠Α͏
})
}
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x/tools/analysisΛ͍ͬͯΔίʔυ
pass.Reportf(
ident.Pos(), // ؒҧ͍ͬͯΔίʔυͷϙδγϣϯ
"conflict identifier name of '%s' by %s.",
name,
pos,
)
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x/tools/analysisΛ͍ͬͯΔίʔυ
package main
import (
"github.com/mackee/conflictident"
"golang.org/x/tools/go/analysis/singlechecker"
)
func main() { singlechecker.Main(conflictident.Analyzer) }
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conflic&dent͕͍ͬͯΔ͜ͱ
• ύοέʔδείʔϓͷܕఆٛΛௐΔ
• ϑΝΠϧείʔϓͷimportએݴΛௐΔ
• ͦΕͧΕͷؔείʔϓͰએݴ͞ΕͯΔม໊ԾҾ໊͕
্ه2ͭͱ͔ͿͬͯͨΒग़ྗΛग़͢
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͜ΕͰ͍͍ײ͡ʹίϚϯυΛ࡞ΕΔʂʂ
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ςετ͕ΊͬͪΌָͳͷΛओு͍ͨ͠
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͜͏͍͏ίϚϯυͷςετͷ͠͞
• ϑΝΠϧΛ৯ͬͯඪ४ग़ྗʹ݁ՌΛग़͢λΠϓͷίϚϯυ
• ࣮ʹΔͱςετ༻ͷϑΝΠϧΛ࡞ͬͯඪ४ग़ྗΛಡΜͰ
จࣈྻύʔεͯ͠...
• ͪΌΜͱೖྗͱग़ྗΛ͚ͯɺςετͰೖग़ྗΛϞοΫ͢Δ
• ↑ x/tools/analysisͰॻ͘ͱࣗવʹ͜Ε͕ग़དྷΔʂʂʂ
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testdataͷ࡞
• testdata/src ҎԼʹ੩తղੳνΣοΧʔͷςετσʔλͷ
ίʔυΛॻ͘
• ςετσʔλͷதʹίϝϯτͰظ͢Δग़ྗΛॻ͘
• ςετଆ x/tools/go/analysis/analysistest Λͬ
ͯهड़͢Δ
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testdata/src/pkgident/pkgident.go
package pkgident
import (
"path"
)
func hoge() {
_ = path.ErrBadPattern
}
func main() {
path, fuga := 1, 1
// want "conflict identifier name of 'path' by testdata/src/pkgident/pkgident.go:4:2."
_, _ = path, fuga
}
func p(path string) {
// want "conflict identifier name of 'path' by testdata/src/pkgident/pkgident.go:4:2."
}
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conflic&dent_test.go
package conflictident_test
import (
"testing"
"github.com/mackee/conflictident"
"golang.org/x/tools/go/analysis/analysistest"
)
func Test(t *testing.T) {
testdata := analysistest.TestData()
analysistest.Run(t, testdata, conflictident.Analyzer, "varspec", "funcarg")
}
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ͦͷଞ͓ಘϙΠϯτ
• go vetͳͲͰݴ͏ ./... Έ͍ͨͳͷͦͷ··͑Δ
• ϞδϡʔϧԽ͍ͯ͠ΔͷͰଞͷLinterͱҰॹʹ࣮ߦ͢ΔίϚϯυ
Λ࡞ΕΔ
• go modulesରԠࡁΈ
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·ͱΊ
• ࢲ͕ϛεΛ͠·͘ΔͷͰɺਖ਼͍͠ίʔυ͕ॻ͚ΔΑ͏ʹ੩తղ
ੳνΣοΧʔΛ࡞Γ·ͨ͠
• golang.org/x/tools/analysis Λ͏ͱLinter͕͔ͳΓ؆
୯ʹॻ͚Δͧʂ
• ղੳʹ͕͔͔࣌ؒΔͷͰνϡʔχϯά͍ͨ͠
• ੩తղੳೖʹ࠷దͳͷͰΈΜͳͬͨΒ͍͍
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Ͱɺ୭ʁ
• mackee_w a.k.a @macopy
• ໘ന๏ਓΧϠοΫ, 3DϓϦϯλ, ࣗ࡞
ΩʔϘʔυ
• ←ࠓि༵ʹחͰΔͷͰདྷͯ͘
Εʂʂʂ
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