Flet is a framework for building interactive multi-platform applications using Python. It allows developers to create user interfaces with Flutter's widgets while writing all the application logic in Python. Flet supports deploying applications as native apps, progressive web apps, or hosting them on Flet's servers.

Pros

• Enables Python developers to create rich, interactive UIs without learning new languages or frameworks
• Supports multiple platforms including desktop, web, and mobile
• Utilizes Flutter's extensive widget library for creating visually appealing interfaces
• Offers a simple and intuitive API for building responsive layouts

Cons

• Limited customization options compared to direct Flutter development
• Performance may be slower than native Flutter apps due to the Python layer
• Relatively new project, which may lead to potential instability or lack of community resources
• Dependency on both Python and Flutter ecosystems

Code Examples

1. Creating a simple counter app:

import flet as ft

def main(page: ft.Page):
    txt_number = ft.TextField(value="0", text_align="right", width=100)

    def minus_click(e):
        txt_number.value = str(int(txt_number.value) - 1)
        page.update()

    def plus_click(e):
        txt_number.value = str(int(txt_number.value) + 1)
        page.update()

    page.add(
        ft.Row(
            [
                ft.IconButton(ft.icons.REMOVE, on_click=minus_click),
                txt_number,
                ft.IconButton(ft.icons.ADD, on_click=plus_click),
            ],
            alignment=ft.MainAxisAlignment.CENTER,
        )
    )

ft.app(target=main)

2. Creating a simple todo list:

import flet as ft

def main(page: ft.Page):
    def add_clicked(e):
        page.add(ft.Checkbox(label=new_task.value))
        new_task.value = ""
        new_task.focus()
        new_task.update()

    new_task = ft.TextField(hint_text="Whats needs to be done?", width=300)
    page.add(ft.Row([new_task, ft.ElevatedButton("Add", on_click=add_clicked)]))

ft.app(target=main)

3. Creating a responsive grid layout:

import flet as ft

def main(page: ft.Page):
    page.add(
        ft.ResponsiveRow(
            [
                ft.Container(ft.Text("1"), padding=5, bgcolor=ft.colors.YELLOW, col={"sm": 6, "md": 4, "xl": 2}),
                ft.Container(ft.Text("2"), padding=5, bgcolor=ft.colors.GREEN, col={"sm": 6, "md": 4, "xl": 2}),
                ft.Container(ft.Text("3"), padding=5, bgcolor=ft.colors.BLUE, col={"sm": 6, "md": 4, "xl": 2}),
                ft.Container(ft.Text("4"), padding=5, bgcolor=ft.colors.PINK, col={"sm": 6, "md": 4, "xl": 2}),
            ]
        )
    )

ft.app(target=main)

Getting Started

To get started with Flet, follow these steps:

1. Install Flet using pip:

   pip install flet
   

2. Create a new Python file (e.g., main.py) and import Flet:

   import flet as ft
   

3. Define your main function and create your UI:

   def main(page: ft.Page):
       page.add(ft.Text("Hello, Flet!"))
   
   ft.app(target=main)
   

4. Run your application:

   python main.py
   

This will launch a simple Flet application with a "Hello, Flet!" message.