https://github.com/medly/ktee
🚰 Tee for Kotlin
https://github.com/medly/ktee
debugging kotlin logging micro-library pipelines tee utility
Last synced: 5 months ago
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🚰 Tee for Kotlin
- Host: GitHub
- URL: https://github.com/medly/ktee
- Owner: medly
- License: mit
- Created: 2020-01-17T03:35:35.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2022-11-19T15:17:00.000Z (over 3 years ago)
- Last Synced: 2024-05-28T19:14:32.808Z (about 2 years ago)
- Topics: debugging, kotlin, logging, micro-library, pipelines, tee, utility
- Language: Kotlin
- Homepage:
- Size: 82 KB
- Stars: 24
- Watchers: 3
- Forks: 2
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# KTee
[](https://sonarcloud.io/dashboard?id=medly_ktee)
[](https://sonarcloud.io/dashboard?id=medly_ktee)
[](https://jitpack.io/#com.medly/ktee)
KTee is Tee for Kotlin code pipelines. If you love the unix command line `tee`, you know what we mean.
## Why?
Often times we need to break a perfect computation pipeline just to be able to log the intermediate values. For example, lets take a look at this code:
```kotlin
(1..10)
.filter { it % 2 == 0 }
.map { it * 2 }
.reduce(Int::plus)
```
If we want to print the result of `filter` or `map` we need to either capture the result into an intermediate `val` or add a `.let { }` with logging statements.
KTee simplifies printing intermediate values dramatically.
## How?
Just `.tee()` it. Seriously! Try this:
```kotlin
(1..10)
.filter { it % 2 == 0 }.tee()
.map { it * 2 }.tee()
.reduce(Int::plus).tee()
```
Which produces following output on the console:
```text
[2, 4, 6, 8, 10]
[4, 8, 12, 16, 20]
60
```
## Can I Customize the output?
We can customize the way `tee` prints using markers and lambda blocks to return custom log messages.
```kotlin
(1..10)
.filter { it % 2 == 0 }.tee("even numbers: ")
.map { it * 2 }.tee("doubles >>>>> ")
.reduce(Int::plus).tee {"the result is $it"}
```
Produces:
```
even numbers: [2, 4, 6, 8, 10]
doubles >>>>> [4, 8, 12, 16, 20]
the result is 60
```
## Can I tee to a `logger`?
We can also log to a custom logger instance (slf4j) instead of `stdout`
```kotlin
(1..10)
.filter { it % 2 == 0 }.teeToDebug(logger)
.map { it * 2 }.teeToTrace(logger)
.reduce(Int::plus).teeToInfo(logger) { "the result is $it" }
```
Produces:
```
[main] DEBUG ktee.KTeeTest - [2, 4, 6, 8, 10]
[main] TRACE ktee.KTeeTest - [4, 8, 12, 16, 20]
[main] INFO ktee.KTeeTest - the result is 60
```
> This output was produced using `slf4j-simple` binding. Your output pattern may look different depending on logger's configuration
## How do I add it to my project?
`ktee` is available in [Maven Central](https://repo.maven.apache.org/maven2/com/medly/ktee/1.0.0/) 🎉
```groovy
repositories {
mavenCentral()
}
dependencies {
implementation 'com.medly:ktee:1.0.0'
}
```