Blog

Sometimes a WordPress plugin or theme update completes without a single PHP error, the admin screen reports success, and yet the live site looks broken the moment you open it. A changed CSS load order, an overwritten font declaration, a clashing class name — these can silently wreck the layout without ever touching an error log. Because nothing throws, nothing gets logged, and nobody notices until a visitor complains. Comparing a screenshot taken before an update against one taken after is one way to catch this “no error, but the page looks wrong” class of problem mechanically. This approach is generally known as visual regression testing. Note: “regression” in software …

If you’ve ever packaged a Python desktop app with PyInstaller, you may have run into this: the app runs perfectly from source, but the frozen executable throws ModuleNotFoundError — and only when you exercise one particular feature. It doesn’t crash on startup. It crashes three clicks deep, in a code path nobody happened to test right after the build. This post breaks down why that happens and what “hidden imports” actually means. Note: PyInstaller is a tool that bundles a Python script together with its dependencies into a single platform-specific executable (a .exe on Windows, or a binary embedded in a .app on macOS), so end users don’t need a …

When you build a desktop app for distribution, macOS may greet users with “cannot be opened because the developer cannot be verified,” and Windows SmartScreen may show “Windows protected your PC” for an unrecognized publisher. Signing and notarizing an app is how you avoid these warnings, but what exactly does that signature prove — and what does it not prove? The distinction is easy to get wrong. Here’s a breakdown of two systems that look similar on the surface but play different roles: Apple’s Notarization and Windows’ Authenticode. Note: Code signing is the umbrella term for attaching a cryptographic signature to an executable so that its author’s identity and the …

Start a Flask app and the terminal prints a familiar line: “WARNING: This is a development server. Do not use it in a production deployment.” Yet plenty of desktop apps bundle that same local Flask server as their actual runtime and keep it running on the user’s machine for the life of the session. That looks like ignoring the warning outright, but the underlying assumptions have actually changed. This article works through what has to change for that warning to become safe to set aside — and what you still have to handle yourself, or it turns into a real bug. Note: WSGI (Web Server Gateway Interface) is the standard …

What happens if the power cuts out while a process is writing to a config file? Or if antivirus software on Windows briefly locks a file mid-write? If you naively overwrite a file with open(path, ‘w’), whatever partial content existed at the moment of interruption is what remains on disk. For JSON, that usually means broken syntax — json.load() throws on the next startup, and the entire configuration is effectively lost. This article walks through a standard technique for preventing that: writing to a temporary file first, then swapping it in atomically. Note: “Atomic” here means an operation either completes entirely or doesn’t happen at all — there’s no partial, …

What happens when a GUI app and a separate background process both try to write to the same configuration file at the same time? If the timing is bad, one write clobbers the other, and in the worst case the file ends up corrupted. File locking is the standard answer to this “concurrent writes from multiple processes” problem. Trying to implement it in pure Python across both Unix-like systems and Windows runs straight into a wall: the two platforms expose completely different APIs. This article walks through that difference from the ground up. Note: “lock” here means inter-process locking — coordinating multiple separate processes on the same machine. That’s different …