We chose the latter.Ī note on pyinstaller: We seriously considered using it in the early stages of the project, but it did not support Python 3 at the time, and more importantly, it suffers from similar limitations as other freezers. While we knew that we wanted to migrate to Python 3, this left us with a choice: invest in the freezer dependencies to add support for Python 3 (and thus the modern compilers) and platform-specific features (like app extensions), or move away from a Python-centric build system, doing away with “freezers” altogether.

Our use of freezer scripts made deploying native code more costly (e.g.

using the Windows Runtime on Windows 10).

Our use of Python 2 prevented us from using new toolchains, making using new APIs more costly (e.g.

We were therefore faced with two problems: Put another way: Xcode makes leveraging these extensions easy, while py2app does not support them altogether. it is launched by the OS) and more stringent requirements for inter-process communication. appex) with custom life cycle rules (i.e. Not merely an API, a FinderSync extension is a full-blown application package (. On macOS, for example, version 10.10 introduced a new app extension for integrating with the Finder. Second, vendors like Microsoft and Apple began introducing new requirements for deploying applications that imposed the use of new, more sophisticated and often proprietary tools (e.g. The tipping point came from changes to how we integrate with each operating system: First, we began introducing increasingly advanced OS extensions-like Smart Sync’s kernel components-that can’t and often shouldn’t be written in Python. To support all these components, this setup.py script-internally named build-all.py-grew to be so large and messy that it became difficult to maintain.

In fact, our code now consists of a mix of TypeScript/HTML, Rust, and Python, as well as Objective-C and C++ for some specific platform integrations. Today, Python is no longer the only language used for development. Over time, our codebase became more and more heterogenous. This Python-focused build system was inspired by distutils: Our application was initially little more than a Python package, so we had a single setup.py-like script to build it. However, rather than use the native toolchains directly, such as Xcode for macOS, we delegated the creation of platform-compliant binaries to py2exe for Windows, py2app for macOS, and bbfreeze for Linux. Initially, we relied on “freezer” scripts to create the native applications for each of our supported platforms. This version is no longer supported by Microsoft and is not compatible with the Windows 10 SDK. For example, Python 2 still technically requires Visual Studio 2008.As we continued to integrate deeply with the operating system, our inability to rely on more recent versions of these toolchains increased the cost of adoption for newer APIs.For example, we use Qt on Windows and Linux: Recent versions of Qt require more modern compilers due to the inclusion of Chromium (via QtWebEngine).The use of older compilers/runtimes was limiting our ability to upgrade some important dependencies.Due to these factors, continued use of Python 2 was associated with a growing maintenance burden: The asyncio project and its async/ await syntax could sometimes remove the need for callbacks, leading to cleaner code.Īs Python 2 has aged, the set of toolchains initially compatible for deploying it has largely become obsolete. Coroutine function syntax: We rely heavily on threading and message-passing-through variants of the Actor pattern and by using Futures-to build many of our features.We’re big fans of MyPy here at Dropbox, so the ability to natively support type annotations is naturally appealing to us. Type annotation syntax: Our codebase is quite large, so the ability to use type annotations has been important to developer productivity.

the str vs bytes rationalization), a few specific features caught our eye: Apart from the (very) long list of general improvements (e.g. As for us, a few key factors influenced our decision to make the jump: This is still somewhat true, though it’s now reached widespread support, with some very popular projects such as Django dropping Python 2 support entirely. Python 3 adoption has long been a subject of debate in the Python community.

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