Kepiye modules, imports lan packages bisa dadi gumana?

Question

IT Interview Practice · Accepted Answer

A **module** iku file `.py` siji-sijine; a **package** iku directory saka modules. **Imports** ngidini sampeyan nggunakake kode saka modules liya, ngorganisir program dadi potongan sing bisa digunakake maneh.

## Modules lan importing

```python
# math_utils.py — a module
def add(a, b): return a + b
PI = 3.14159
```

```python
# main.py — different ways to import
import math_utils                  # import the whole module
math_utils.add(2, 3)               # access via the module name

from math_utils import add, PI     # import specific names
add(2, 3)                          # use directly

from math_utils import add as plus # import with an alias
import numpy as np                 # common aliasing convention
```

## Packages — directory saka modules

```text
mypackage/
  __init__.py        ← marks it as a package (can be empty)
  module_a.py
  subpackage/
    __init__.py
    module_b.py
```

```python
from mypackage.module_a import something
from mypackage.subpackage.module_b import other
```

File `__init__.py` nandai directory minangka package (lan bisa nglakoni kode package-init utawa netepake apa sing `from package import *` wujudake).

## `if __name__ == "__main__"` idiom

```python
def main():
    print("running as a script")

if __name__ == "__main__":   # True only when run directly, not when imported
    main()
```

Iki ngidini file dadi module sing bisa di-import *lan* script sing bisa dijalanake — kode ing ngisor iki mung laku nalika file dilakoni langsung (`python file.py`), ora nalika di-import. Idiom Python sing umum banget.

## Nang endi Python nggoleki modules

```python
import sys
sys.path   # the list of directories Python searches for imports
# includes: the current directory, installed packages (site-packages), stdlib
```

## Standard library lan third-party

```python
import os, json, datetime    # standard library — "batteries included"
import requests              # third-party — installed via pip from PyPI
```

## Kangapa iki penting

Modules lan packages minangka cara sampeyan ngorganisir kode Python dadi unit sing bisa digunakake maneh, gampang dirawat - bukan file raksasa - penting banget kanggo project sing ora prasaja.

Ngerti gaya import, struktur package (`__init__.py`), idiom `if __name__ == "__main__"` (prilaku dual script/module), lan kepiye Python nggoleki modules (`sys.path`) penting banget kanggo ngatur project, ngulang kode, lan nggunakake standard library lan ekosistem PyPI sing akeh.

Import errors lan kebingungan struktur minangka alangan awal sing umum sing kasunyatan iki bisa ngatasi.

Kepiye modules, imports lan packages bisa dadi gumana?

Modules lan importing

Packages — directory saka modules

`if name == "main"` idiom

Nang endi Python nggoleki modules

Standard library lan third-party

Kangapa iki penting

Pitakon sing gegandhengan

Modules lan importing

Packages — directory saka modules

if __name__ == "__main__" idiom

Nang endi Python nggoleki modules

Standard library lan third-party

Kangapa iki penting

Pitakon sing gegandhengan

`if name == "main"` idiom