Warning: Colourful language ahead. (My colours are way duller than most though, so your mileage may vary.)

Every now and then I have episodes of deep reflection on languages and semantics, and not just programming languages either. A common phrase for one speaking junk or bullshit is to ‘speak out of one’s @$$/arse/{insert other posterior synonym} (henceforth aliased to the less-accurate-but-will-do term $POSTERIOR in the interest of the DRY principle)’, or ‘did you just pull that out of your $POSTERIOR’, and so on. In my ever so humble view, these phrases and their variations should be used rather carefully and I am not simply looking at it from the viewpoint of manners and aesthetics either. Let’s consider a few comparisons:

The excretory organs, including parts involved in the aforementioned $POSTERIOR expel toxins and unused junk out of the body, ensuring normal functioning of the digestive system, and in fact the body as a whole all things considered – you are what you eat and all that. In many cases, when one speaks out of one’s $POSTERIOR, it is often a trait that is repeated, because one is still evolving, as we all are, or perhaps has chosen not to evolve – also a choice made by many. Neither good nor bad; it just is, no judgement (no, really). The point is that more often than not, this wannabe-$POSTERIOR produce is not expelled for good, rather its source is often more like a bottomless pit (no pun intended.. well maybe just a little).

An astute reader (like yours truly, who just thought of this, teehee) will also bring up that even in the case of the true $POSTERIOR, it can be a bottomless pit – for one keeps eating and recycling, more so if the intake is … excessive – but the crucial invariant here is that output is always less than or equal to input (in fact equal is quite unlikely I think?) for true $POSTERIOR. Contrast this with case of speech or ideas ejected from wannabe-$POSTERIOR: even without additional intake (i.e. no new incoming less-than-valuable ideas to process), the junky output is sometimes reduced, often remains constant, but usually increases. On the rare occasion, it is eliminated. Quite a different invariant, yes?

Hence these phrases make use of flawed comparisons, i.e. wannabe-$POSTERIOR <> true-$POSTERIOR, they are not even all that similar.

These phrases in fact do a disservice to the true $POSTERIOR. They give $POSTERIOR a bad name. The $POSTERIOR works in all ernest supporting life. It is a Divine gift (have you considered life without it?). The bullshit output via the wannabe-$POSTERIOR, on the other hand, quite simply, does not necessarily do the same.

I shall however submit that the outputs (wannabe-output vs true-output) share many more traits, and are worthy of comparison. But let us not discredit true $POSTERIOR unnecessarily.

Please consider the ideas put forward in this post the next time you decide to use phrases involving $POSTERIOR.

Thank you. I wish you, and your $POSTERIOR, fragrances of heavenly descent.

PS. I have also tagged this as software_dev, for I think they kinda explain invariants and DRY rather nicely.