Friday, January 28, 2022

Avoiding the Deadly Quadrant

I saw a video (opens in a new window) recently which illustrated an important concept in a very elegant way. 

This is important, because in 3/4 of this diagram, your code is inherently safe to run in a multi-threaded environment.  There are no synchronization blocks required, there is no need for complicated gatekeeping.  And yet, somehow a lot of code winds up with mutable data and synchronization headaches.

Applying just a few functional programming principles to your work can go a long way.  Parameters should generally be considered inviolate, use return properly and don't try modifying your inputs directly.  Prefer constants to variables. 

When you kick off a process, you really don't want it randomly reaching out and modifying some kind of global state.  If it REALLY needs to send messages home, give it a tool to do so, such as a callback function it can use for that purpose.

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