Created
December 13, 2018 20:00
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Kotlin newInstance() Fragment pattern
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| /** | |
| * Eases the Fragment.newInstance ceremony by marking the fragment's args with this delegate | |
| * Just write the property in newInstance and read it like any other property after the fragment has been created | |
| * | |
| * Inspired by Adam Powell, he mentioned it during his IO/17 talk about Kotlin | |
| */ | |
| class Argument<T : Any> : kotlin.properties.ReadWriteProperty<Fragment, T> | |
| { | |
| var value: T? = null | |
| override operator fun getValue(thisRef: android.support.v4.app.Fragment, property: kotlin.reflect.KProperty<*>): T | |
| { | |
| if(value == null) | |
| { | |
| val args = thisRef.arguments ?: throw IllegalStateException( | |
| "Cannot read property ${property.name} if no arguments have been set") | |
| @Suppress("UNCHECKED_CAST") | |
| value = args.get(property.name) as T | |
| } | |
| return value ?: throw IllegalStateException("Property ${property.name} could not be read") | |
| } | |
| override operator fun setValue(thisRef: android.support.v4.app.Fragment, property: kotlin.reflect.KProperty<*>, value: T) | |
| { | |
| if(thisRef.arguments == null) thisRef.arguments = android.os.Bundle() | |
| val args = thisRef.arguments | |
| args?.let { | |
| val key = property.name | |
| when(value) | |
| { | |
| is String -> args.putString(key, value) | |
| is Int -> args.putInt(key, value) | |
| is Short -> args.putShort(key, value) | |
| is Long -> args.putLong(key, value) | |
| is Byte -> args.putByte(key, value) | |
| is ByteArray -> args.putByteArray(key, value) | |
| is Char -> args.putChar(key, value) | |
| is CharArray -> args.putCharArray(key, value) | |
| is CharSequence -> args.putCharSequence(key, value) | |
| is Float -> args.putFloat(key, value) | |
| is Bundle -> args.putBundle(key, value) | |
| is Binder -> BundleCompat.putBinder(args, key, value) | |
| is android.os.Parcelable -> args.putParcelable(key, value) | |
| is java.io.Serializable -> args.putSerializable(key, value) | |
| else -> throw IllegalStateException( | |
| "Type ${value.javaClass.name} of property ${property.name} is not supported") | |
| } | |
| } | |
| } | |
| } | |
| class NullableArgument<T> : kotlin.properties.ReadWriteProperty<Fragment, T?> | |
| { | |
| var value: T? = null | |
| override operator fun getValue(thisRef: android.support.v4.app.Fragment, property: kotlin.reflect.KProperty<*>): T? | |
| { | |
| // If the fragment does not have any arguments, we assume that no properties were provided | |
| if(thisRef.arguments == null) | |
| { | |
| return null | |
| } | |
| if(value == null) | |
| { | |
| val args = thisRef.arguments ?: throw IllegalStateException( | |
| "Cannot read property ${property.name} if no arguments have been set") | |
| @Suppress("UNCHECKED_CAST") | |
| value = args.get(property.name) as T? | |
| } | |
| return value | |
| } | |
| override operator fun setValue(thisRef: android.support.v4.app.Fragment, property: kotlin.reflect.KProperty<*>, value: T?) | |
| { | |
| if(value == null) | |
| { | |
| return | |
| } | |
| if(thisRef.arguments == null) thisRef.arguments = android.os.Bundle() | |
| val args = thisRef.arguments | |
| args?.let { | |
| val key = property.name | |
| when(value) | |
| { | |
| is String -> args.putString(key, value) | |
| is Int -> args.putInt(key, value) | |
| is Short -> args.putShort(key, value) | |
| is Long -> args.putLong(key, value) | |
| is Byte -> args.putByte(key, value) | |
| is ByteArray -> args.putByteArray(key, value) | |
| is Char -> args.putChar(key, value) | |
| is CharArray -> args.putCharArray(key, value) | |
| is CharSequence -> args.putCharSequence(key, value) | |
| is Float -> args.putFloat(key, value) | |
| is Bundle -> args.putBundle(key, value) | |
| is Binder -> BundleCompat.putBinder(args, key, value) | |
| is android.os.Parcelable -> args.putParcelable(key, value) | |
| is java.io.Serializable -> args.putSerializable(key, value) | |
| is Any -> throw IllegalStateException( | |
| "Type ${value.javaClass.name} of property ${property.name} is not supported") | |
| else -> throw IllegalStateException( | |
| "Property ${property.name} is not supported") | |
| } | |
| } | |
| } | |
| } |
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