MessageFormat2

This is a Python implementation of the Unicode Message Format 2.0 specification.

Message Format 2.0 (MF2) is a new iteration of Message Format which aims to be more expressive and flexible than both Message Format 1.0 and, in the context of Python, gettext.

If you would like to learn more about MF2 itself head over to the Unicode technical specification.

Features

The library includes:

• A message parser and a formatter
• Several builtin formatters and selectors described by the spec and the possibility to write custom formatters/selectors
• Helper classes to inspect and transform the message data model

Documentation

Installation

Via pip for Python >= 3.12

pip install messageformat2

Examples

Simple messages

from messageformat2 import format_message

format_message("Hello, {$name}!", {"name": "Alice"})  # -> "Hello, Alice!"

Messages can be reused with different inputs.

from messageformat2 import Message

message = Message("Hello, {$name}!")
message.format({"name": "Alice"})  # -> "Hello, Alice!"
message.format({"name": "Bob"})  # -> "Hello, Bob!"

Built-in formatters

There are several builtin locale-aware formatters available.

from datetime import datetime
from messageformat2 import Message

message = Message("Today's date is {$now :date}")
now = datetime.now()
message.format({"now": now}, locale='en_US')
# -> Today's date is 5/10/2024
message.format({"now": now}, locale='en_GB')
# -> Today's date is 10/05/2024

Plural support

MF2 supports pluralization using built-in or custom selectors.

from messageformat2 import Message

msg = Message ("""\
.match {$count :number}
one {{You have {$count} notification.}}
*   {{You have {$count} notifications.}}
""")

msg.format({"count": 42}, locale='en_US') # -> "You have 42 notifications."
msg.format({"count": 1}, locale='en_US') # -> "You have 1 notification."

Complete documentation is available here.