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Kotlin 1.3
͞ΒͬͱContracts + α
LINE Developers Meetup #47 in Fukuoka
@dashimaki_dofu
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ϓϩϑΟʔϧ
• ໊લ: ߴ Յହ (Yoshiyasu KO)
• ॴଐ: ϕΨίʔϙϨʔγϣϯ
• AndroidΤϯδχΞ
• : @dashimaki_dofu
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ϓϩϑΟʔϧ
ʮ͠ΜͪΌΜͷਓʯͱ֮͑ͯؼ͍ͬͯͩ͘͞
• ໊લ: ߴ Յହ (Yoshiyasu KO)
• ॴଐ: ϕΨίʔϙϨʔγϣϯ
• AndroidΤϯδχΞ
• : @dashimaki_dofu
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What is Kotlin?
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Kotlinʢ͜ͱΓΜʣ
• 2013 JetBrains͕ࣾ։ൃͨ͠
ΦϒδΣΫτࢦܕݴޠ
• JVM্Ͱಈ࡞
• Android Studio 3.0ΑΓ
ެࣜαϙʔτ
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2018.10.30
Kotlin 1.3ϦϦʔεʂ
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Kotlin 1.3
• Coroutines ਖ਼ࣜ൛
• Kotlin/Native β൛
• Contracts
• when Ҿͷείʔϓ࠷దԽ etc...
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Kotlin 1.3
• Coroutines ਖ਼ࣜ൛
• Kotlin/Native β൛
• Contracts
• when Ҿͷείʔϓ࠷దԽ etc...
ࠓ͢ͷͪ͜Β
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Contracts
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Contracts = ܖ
• ؔͷৼΔ͍Λʮܖʯ͢Δ
• ίϯύΠϥʹؔͷৼΔ͍Λڭ͑Δ
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?????
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Smart Cast
fun foo(s: String?) {
if (s != null) s.length
}
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Smart Cast
fun foo(s: String?) {
if (s != null) s.length
} T/VMMBCMF
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Smart Cast
fun foo(s: String?) {
if (s != null) s.length
}
/PU/VMMΛอূ
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Smart Cast
fun foo(s: String?) {
if (s != null) s.length
}
/PU/VMMΛอূ ͕ෆཁ
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ྫ: isNullOrEmpty()
fun foo(s: String?) {
if (!s.isNullOrEmpty()) s!!.length
}
~ Kotlin 1.2
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ྫ: isNullOrEmpty()
fun foo(s: String?) {
if (!s.isNullOrEmpty()) s!!.length
}
T͕ʮOVMMPSۭจࣈʯͰ͋ΕUSVF
OVMMͰۭจࣈͰͳ͚ΕGBMTF
GBMTFͰ͋Ε/PU/VMM͕อূ͞ΕΔͣ
~ Kotlin 1.2
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ྫ: isNullOrEmpty()
fun foo(s: String?) {
if (!s.isNullOrEmpty()) s!!.length
}
ίϯύΠϥJT/VMM0S&NQUZͷʮৼΔ͍ʯ͕͔Βͳ͍
4NBSU$BTU͕ޮ͔ͳ͍ɾɾɾ
~ Kotlin 1.2
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ྫ: isNullOrEmpty()
fun foo(s: String?) {
if (!s.isNullOrEmpty()) s.length
}
Kotlin 1.3
JT/VMM0S&NQUZʹ࣮͞Εͨ$POUSBDUTʹΑͬͯ
4NBSU$BTU͕ޮ͘Α͏ʹͳΔʂ
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ྫ: isNullOrEmpty()
@kotlin.internal.InlineOnly
public inline fun CharSequence?.isNullOrEmpty(): Boolean {
contract {
returns(false) implies (this@isNullOrEmpty != null)
}
return this == null || this.length == 0
}
Kotlin 1.3
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ྫ: isNullOrEmpty()
@kotlin.internal.InlineOnly
public inline fun CharSequence?.isNullOrEmpty(): Boolean {
contract {
returns(false) implies (this@isNullOrEmpty != null)
}
return this == null || this.length == 0
}
Kotlin 1.3
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ྫ: isNullOrEmpty()
@kotlin.internal.InlineOnly
public inline fun CharSequence?.isNullOrEmpty(): Boolean {
contract {
returns(false) implies (this@isNullOrEmpty != null)
}
return this == null || this.length == 0
}
%4- ޙड़
Ͱهड़͞ΕΔ
Kotlin 1.3
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ྫ: isNullOrEmpty()
@kotlin.internal.InlineOnly
public inline fun CharSequence?.isNullOrEmpty(): Boolean {
contract {
returns(false) implies (this@isNullOrEmpty != null)
}
return this == null || this.length == 0
}
GBMTFΛฦ࣌͢
Kotlin 1.3
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ྫ: isNullOrEmpty()
@kotlin.internal.InlineOnly
public inline fun CharSequence?.isNullOrEmpty(): Boolean {
contract {
returns(false) implies (this@isNullOrEmpty != null)
}
return this == null || this.length == 0
}
GBMTFΛฦ࣌͢ /PU/VMMΛอূ͢Δ͜ͱΛ
ܖ͢Δ
Kotlin 1.3
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ྫ: isNullOrEmpty()
@kotlin.internal.InlineOnly
public inline fun CharSequence?.isNullOrEmpty(): Boolean {
contract {
returns(false) implies (this@isNullOrEmpty != null)
}
return this == null || this.length == 0
}
GBMTFΛฦ࣌͢ /PU/VMMΛอূ͢Δ͜ͱΛ
ܖ͢Δ
ίϯύΠϥʹؔͷৼΔ͍Λ͑Δ͜ͱ͕Ͱ͖Δ
Kotlin 1.3
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Contracts DSL
• returns()
• ؔͷ࣮ߦʹޭͨ࣌͠
• returns(Boolean?)
• ͕ؔҾͷΛฦͨ࣌͠
• returnsNotNull()
• ͕ؔNotNullΛฦͨ࣌͠
• callsInPrace(block, InvocationKind)
• block ͕ݺΕΔճΛ InvocationKind Ͱอূ͢Δ
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Contracts DSL
• returns()
• ؔͷ࣮ߦʹޭͨ࣌͠
• returns(Boolean?)
• ͕ؔҾͷΛฦͨ࣌͠
• returnsNotNull()
• ͕ؔNotNullΛฦͨ࣌͠
• callsInPrace(block, InvocationKind)
• block ͕ݺΕΔճΛ InvocationKind Ͱอূ͢Δ
ࣗͰ$POUSBDUΛ࡞ΕΔ
$VTUPN$POUSBDUT
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when Ҿͷείʔϓ࠷దԽ
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when Ҿͷείʔϓ࠷దԽ
fun Request.getBody() {
val response = executeRequest()
return when (response) {
is Success -> response.body
is HttpError -> throw HttpException(response.status)
}
}
~ Kotlin 1.2
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when Ҿͷείʔϓ࠷దԽ
fun Request.getBody() {
val response = executeRequest()
return when (response) {
is Success -> response.body
is HttpError -> throw HttpException(response.status)
}
}
~ Kotlin 1.2
ϩʔΧϧมΛ͜͜Ͱ
ఆٛ͢Δඞཁ͕͋Δ
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when Ҿͷείʔϓ࠷దԽ
fun Request.getBody() {
val response = executeRequest()
return when (response) {
is Success -> response.body
is HttpError -> throw HttpException(response.status)
}
}
~ Kotlin 1.2
ϩʔΧϧมΛ͜͜Ͱ
ఆٛ͢Δඞཁ͕͋Δ
XIFO͚ͩͰ͏มͷείʔϓ͕͕ͬͯ͠·͏
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when Ҿͷείʔϓ࠷దԽ
fun Request.getBody() =
when (val response = executeRequest()) {
is Success -> response.body
is HttpError -> throw HttpException(response.status)
}
Kotlin 1.3
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when Ҿͷείʔϓ࠷దԽ
fun Request.getBody() =
when (val response = executeRequest()) {
is Success -> response.body
is HttpError -> throw HttpException(response.status)
}
Kotlin 1.3
ҾͰϩʔΧϧม͕
ఆٛͰ͖Δ
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when Ҿͷείʔϓ࠷దԽ
fun Request.getBody() =
when (val response = executeRequest()) {
is Success -> response.body
is HttpError -> throw HttpException(response.status)
}
Kotlin 1.3
ҾͰϩʔΧϧม͕
ఆٛͰ͖Δ
ҾͰར༻͢ΔมͷείʔϓΛ
XIFOϒϩοΫͰऩΊΔ͜ͱ͕Ͱ͖Δ
\
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ࠓͨ͜͠ͱ
• Contract
• ίϯύΠϥʹؔͷʮৼΔ͍ʯΛ͑Δ
• ελϯμʔυϥΠϒϥϦʹΈࠐ·Ε͍ͯΔ
• DSL Ͱهड़͞ΕΔ
• Custom Contracts ఆٛͰ͖Δ
• when จͷҾͷείʔϓ࠷దԽ
• ϩʔΧϧมΛҾͰఆٛͰ͖Δ
• when ϒϩοΫʹείʔϓ͕ऩΊΒΕΔ
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·ͱΊ
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͔Ώ͍ॴʹ
ख͕ಧ͍ͨκʂ
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͡Ό
ͦΏ͜ͱͰʙ