universal-common

A library that extends the Python base class library with utility functions and types, inspired by the .NET base class library and language features - without needing full feature parity, just enough to make everyday Python a little saner.

Features

• Null-coalescing (coalesce) and null/whitespace string checks (is_null_or_empty, is_null_or_white_space)
• LINQ-style iteration helpers (first, first_or_default, last, last_or_default), available both as free functions and as methods on List
• Dictionary: a dict subclass that also supports attribute access
• event/BoundEvent: a C#-style event pattern with +=/-= subscription
• Stopwatch: a simple elapsed-time measurer, usable as a context manager
• MediaType: parsing and building MIME media type strings (e.g. "application/json; charset=utf-8")
• SemanticVersion: dependency-free Semantic Versioning 2.0.0 parsing and comparison
• SqlConnectionStringBuilder: a minimal SQL connection string builder/parser
• Environment/SpecialFolder: cross-platform special-folder lookup (app data, cache, desktop, documents, downloads, ...), with zero third-party dependencies

Installation

Install the package from PyPI using pip:

pip install universal-common

Usage

Null coalescing and string checks

from universal_common import coalesce, is_null_or_empty, is_null_or_white_space

coalesce(None, None, 3)          # 3 - first non-None value
is_null_or_empty(None)           # True
is_null_or_empty("")             # True
is_null_or_white_space("   ")    # True - unlike `if not s:`, this catches whitespace-only strings

LINQ-style iteration helpers

from universal_common import first, first_or_default, last, last_or_default, List

numbers = [1, 2, 5, 4]
first(numbers)                          # 1
first(numbers, lambda x: x > 3)         # 5
last(numbers)                           # 4
last_or_default(numbers, lambda x: x > 10)  # None, instead of raising

# The same methods are available directly on List:
items = List([1, 2, 5, 4])
items.first_or_default(lambda x: x > 3)  # 5
items.last()                             # 4

first/last raise ValueError when nothing matches; first_or_default/last_or_default return None instead.

Attribute-accessible dictionaries

from universal_common import Dictionary

settings = Dictionary({"name": "Ada"})
settings.name        # "Ada"
settings["name"]     # "Ada"
settings.age = 30    # same as settings["age"] = 30
settings.missing     # None, does not raise

C#-style events

from universal_common import event

class Button:
    @event
    def clicked(self):
        """Raised when the button is clicked."""

button = Button()
button.clicked += lambda: print("clicked!")
button.clicked()  # invokes every subscribed handler

If more than one handler raises, every handler still runs; the first exception is raised, and any additional ones are attached to it as .other_exceptions rather than silently discarded.

Timing

from universal_common import Stopwatch

with Stopwatch() as stopwatch:
    do_work()
print(stopwatch.elapsed, "seconds")

# Or standalone:
stopwatch = Stopwatch.start_new()
do_work()
stopwatch.stop()
print(stopwatch.elapsed_milliseconds, "ms")

Media types

from universal_common import MediaType

media_type = MediaType.parse("application/json; charset=utf-8")
media_type.full_type   # "application/json"
media_type.charset     # "utf-8"
str(media_type)        # "application/json; charset=utf-8"

Semantic versioning

from universal_common import SemanticVersion

version = SemanticVersion.parse("1.2.3-beta.1+build.5")
version.major, version.minor, version.patch  # (1, 2, 3)

SemanticVersion.parse("1.0.0-alpha") < SemanticVersion.parse("1.0.0")  # True
sorted([SemanticVersion.parse(v) for v in ["2.0.0", "1.0.0", "1.5.0"]])

Comparison follows the semver 2.0.0 precedence rules exactly: numeric identifiers sort before alphanumeric ones, a version without a prerelease outranks one with a prerelease at the same major.minor.patch, and build metadata (+...) is ignored for comparison.

SQL connection strings

from universal_common import SqlConnectionStringBuilder

builder = SqlConnectionStringBuilder()
builder.server = "localhost"
builder.database = "app"
builder.user_id = "admin"
builder.password = "hunter2"
str(builder)  # "Server=localhost;Database=app;Uid=admin;Pwd=hunter2"

parsed = SqlConnectionStringBuilder.parse("Server=localhost;Database=app")
parsed.server    # "localhost"

Special folders

from universal_common import Environment, SpecialFolder

Environment.get_folder_path(SpecialFolder.APPLICATION_DATA)   # %APPDATA%, ~/Library/Application Support, or $XDG_CONFIG_HOME
Environment.get_folder_path(SpecialFolder.LOCAL_APPLICATION_DATA)
Environment.get_folder_path(SpecialFolder.CACHE)
Environment.get_folder_path(SpecialFolder.DESKTOP)
Environment.get_folder_path(SpecialFolder.DOCUMENTS)
Environment.get_folder_path(SpecialFolder.DOWNLOADS)

This mirrors most (not all - CACHE and DOWNLOADS aren't real Environment.SpecialFolder members, added because they're commonly needed) of a useful subset of .NET's Environment.SpecialFolder - the ones that resolve sensibly on Windows, macOS, and Linux.

License

CC0 1.0 Universal (Public Domain Dedication).