219 lines
3.6 KiB
Markdown
219 lines
3.6 KiB
Markdown
# 06 – Packages and Modules in Python
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This document explains how **modules**, **packages**, and the `__name__` concept work in Python.
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These features help organize code, reuse functionality, and build scalable projects.
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---
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## 1. Importing External Modules
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Python allows you to import **external libraries** installed in your environment.
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### Example: Using the `emoji` Module
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### Code
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```python
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import emoji
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print(emoji.emojize("abbas is :red_heart:"))
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```
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### Explanation
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* `import emoji` imports the entire `emoji` module.
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* `emoji.emojize()` converts emoji aliases into actual emoji characters.
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* You must use the module name (`emoji`) to access its functions.
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---
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### Importing a Specific Function
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### Code
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```python
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from emoji import emojize
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print(emojize("abbas is :red_heart:"))
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```
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### Explanation
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* `from emoji import emojize` imports only the `emojize` function.
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* You can call the function directly without prefixing the module name.
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* This approach is cleaner when you only need a specific function.
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---
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## 2. Creating a Module
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A **module** is a single Python file containing functions, classes, or variables.
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### File Structure
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```
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hi.py
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main.py
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```
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### `hi.py`
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```python
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def hi():
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print("Hi :)")
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```
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### `main.py`
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```python
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import hi
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hi.hi()
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```
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### Explanation
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* `hi.py` is a module.
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* `hi()` is a function defined inside the module.
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* `import hi` loads the module.
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* `hi.hi()` calls the function from the module.
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---
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## 3. Creating a Package
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A **package** is a directory that contains multiple modules.
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### Package Structure
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```
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honor/
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│── __init__.py
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│── hi.py
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main.py
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```
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### `honor/hi.py`
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```python
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def hello():
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print("Hi :)")
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```
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### `honor/__init__.py`
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```python
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```
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### Explanation
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* The `honor` directory is a package.
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* `__init__.py` tells Python that this directory is a package.
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* The file can be empty, but it **must exist** (especially for older Python versions and clarity).
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---
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### Importing from a Package (Method 1)
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### `main.py`
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```python
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from honor import hi
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hi.hello()
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```
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#### Explanation
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* Imports the `hi` module from the `honor` package.
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* Accesses the function using `hi.hello()`.
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---
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### Importing from a Package (Method 2)
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### `main.py`
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```python
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from honor.hi import hello
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hello()
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```
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#### Explanation
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* Imports the `hello` function directly.
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* Allows calling the function without the module name.
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* Cleaner when only one function is needed.
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---
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## 4. The `__name__` Concept
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Every Python file has a built-in variable called `__name__`.
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### Code
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```python
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print(__name__)
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```
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### Behavior
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#### When a File Is Run Directly
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```bash
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python3 abbas.py
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```
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Output:
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```text
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__main__
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```
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* This means the file is the **entry point** of the program.
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#### When a File Is Imported
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```python
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import abbas
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```
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Output:
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```text
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abbas
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```
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* `__name__` is set to the **module name**, not `__main__`.
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---
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## 5. Why `__name__ == "__main__"` Is Important
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This pattern allows code to run **only when the file is executed directly**, not when imported.
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### Example
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```python
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def main():
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print("Running directly")
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if __name__ == "__main__":
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main()
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```
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### Explanation
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* The code inside the `if` block runs only when the file is executed directly.
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* Prevents unwanted execution when the file is imported as a module.
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* This is a standard Python best practice.
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---
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## Summary
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* **Module**: A single `.py` file
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* **Package**: A directory containing modules
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* `__init__.py`: Marks a directory as a package
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* `import module`: Imports the whole module
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* `from module import item`: Imports specific items
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* `__name__`: Identifies how a file is executed
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