build3r/TodayILearned

Long Term Knowledge

Code base: One app should have one repo, if multiple app are sharing code then it should be refactored into library. One repo will have multiple deployments (prod, staging, local, variants etc)
Dependencies: All projects should have a explicit dependency declaration and isolation from system dependency. If the app relies of system dependencies then it should be statically linked.
Configuration: Any value like endpoints, keys etc should be refactored into configs. Best is to add them to env variables. They should not be committed to version control. In android it might not work, as we have to bundle them in apk. But we can still maintain configs separately.
Resources: Both local and 3rd party services should be considered as attached resources. The resource should be referred only by the url/locator service. There should be only config change and no code change to swap our resources.
Build, Release, Run: The build state transforms code into runnable, the release stage adds config to the runnable, the run stage take the release and executes it in the execution environment. The whole pipe line in one way flow and any new changes will require a new release. The run stage should be light weight and should able to run without user intervention in case of restarts.

Activity Results API
Android dependency Graph
Constraint Layout with percentage
Vector Assets
Work Manager
Pull Apk from Device
1. get Path adb shell pm path com.example.someapp
2. Get APK adb pull /data/app/com.example.someapp-2.apk
Securing Keys in NDK Layer: You can store api key in the NDK layer which makes it difficult for bad actors to access them. Easy way is just add include C++ while creating project and add kets in native-lib.cpp file.
Best Way to SHA1, SHA256 and MD5 signatures of your debug or signing certificate
- Set the appropriate variant
- ./gradlew signingReport
- You can even click gradle -> Project -> app -> tasks -> android -> signingReport
To get an APKCertSha256Digest
- keytool -printcert -jarfile ~/PATH_TO/YOURAPKFILE.apk | grep "SHA256: " | cut -d " " -f 3 | xxd -r -p | openssl base64
- echo "SHA256_TEXT_REPRESENTATION" | xxd -r -p | openssl base64
- xxd does a hex dump of input, basically text to binary

Intro to Pandas
1. If you make a column as index you can't access it with [colum] you will have to use df.index
2. GroupBy you can directly call sum

Python List Comprehension A list comprehension looks like this:
new_list = [f(o) for o in a_list if o>0]
This will return every element of a_list that is greater than 0, after passing it to the function f.

You can use the ADB accessibility to change the density of Physical Device or Emulator to test you app UI on small screen devices

adb shell wm density //see current density
adb shell wm density 580 //set a different density
adb shell wm density reset //reset denity to default

Switch On a PC remotely
vscode-snippet (Easily search common code snippets)
using launchd to run cron jobs
Espanso Really cool utility which you can use to create text substitution
AWK
Redux Thunk
Optimizing Big query Execution
Shallow Backup Simple tool to backup your dot files, package list, fonts and configs. Has inbuilt git integration.
Glitch Online tool to create websites and host directly.

Command-Option-C will copy the file path
Holding control during screenshot will copy directly to clipboard
Apple Books Directory /Users/<Name>/Library/Mobile Documents/iCloud~com~apple~iBooks/Documents

Multi Digit Multiplication
Kotlin Collections
SQL
GitFlow
Design Patterns
SQL Best Practices
Firebase Gotchas
Technical Writing
Kotlin Coroutines Exception Handling
Various ways of Handling Exception In Coroutines
- runCatching is Kotlin idiomatic way for try-catch
- Coroutine exception handler should be rarely used, won't work in scopes or inbuilt scopes like lifeCycle or viewModelScope.
- you can use handler directly with supervisorJob.
- It better user supervisorJob most of the time as it doesn't cancel other children when one fails.
Kotlin, Coroutines and Flows
In Java and Kotlin the func invocation is *pass-by-value for primitive types(Primitive object like Integer etc) (only java) if you modify the value of pass parameter it does not change but if it is an object the any modification done in function will reflected in the original object. More Details
Kotlin joinToString (1..100).joinToString(separator = "\n") { "$it. Point" }
Kotlin Flows

You won't get anywhere by making other people feel stupid, no matter how correct you are.
Being kind is harder than being clever.

Inspired by ashandilya

A repo where I list thing which I learn daily for sharing and referring back

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