WhatIf

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Language
Kotlin
Version
1.0.0 (Sep 8, 2019)
Created
Sep 8, 2019
Updated
Sep 8, 2019
Owner
Jaewoong Eum (skydoves)
Contributor
Jaewoong Eum (skydoves)
1
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WhatIf

☔ WhatIf is kotlin extensions for expressing a single if-else statement, nullable and boolean.

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Gradle

Add a dependency code to your module's build.gradle file.

dependencies {
    implementation "com.github.skydoves:whatif:1.0.0"
}

Usage

WhatIf

WhatIf is an expression for invoking whatIf lambda when the given boolean is true and not-null.

val nullableBoolean: Boolean? = true
whatIf(nullableBoolean) {
  log("not-null and true : $nullableBoolean")
}

Here is an extension for nullable booleans.

nullableBoolean.whatIf {
  log("not-null and true : $nullableBoolean")
}

WhatIfNot

The whatIf expression is basically composed with given, whatIf, whatIfNot. If the target is null or false, If we do not need to handle whatIfNot case, it can be omitted.whatIfNot will be invoked instead of the whatIf.


whatIf(
  given = nullableBoolean,
  whatIf = { log("not-null and true : $nullableBoolean") },
  whatIfNot = { log("null or false : $nullableBoolean") }
)

Or here is an extension for nullable boolean.

nullableBoolean.whatIf(
  whatIf = { log("not-null and true : $nullableBoolean") },
  whatIfNot = { log("not-null or false : $nullableBoolean") }
)

WhatIf in the builder pattern

Sometimes we should set builder differently to depend on options. It can be applied to any builder patterns like AlertDialog.Builder or anything.WhatIf is useful when using a chaining function like a builder pattern.


val balloon = Balloon.Builder(baseContext)
  .setArrowSize(10)
  .setArrowVisible(true)
  .whatIf(nullableBoolean) { setTextColor(Color.YELLOW) }
  .whatIf(nullableBoolean, { setText("Hello, whatIf") }, { setText("Good-Bye whatIf") })
  .setWidthRatio(1.0f)
  .build()

WhatIfNotNull

WhatIfNotNull is an expression for invoking [whatIf] lambda when the target object is not null.

val nullableObject: Person? = Person()
nullableObject.whatIfNotNull {
  log("$it is not null")
}

And we can handle the null case. If the target is null, [whatIfNot] will be invoked instead of the [whatIf].

nullableObject.whatIfNotNull(
  whatIf = { log("$it is not null.") },
  whatIfNot = { log("$it is null.") }
)

WhatIfLet

The basic concept is the same as whatIf but it is useful when the receiver and the result should be different.

val length = nullableString?.whatIfLet(
  given = nullableString.length < 5,
  whatIf = { it.length },
  whatIfNot = {
    log("$it, length can not over than 5.")
    5
  }
)

We can use default value instead of the whatIfNot and can be omitted the whatIfNot.

val length = nullableString?.whatIfLet(
  nullableString.length < 5,
  default = nullableString.length) { 
  log("$it, length can not over than 5.")
  5
}

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License

Copyright 2019 skydoves (Jaewoong Eum)

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.