[slovenlyrobot]

I recognize it may be difficult to understand, but this is a thread about backwards compatibility. Of course if I had any faith in the contemporary Python community, I would still be treating Python as a serious programming language and not be suggesting this is a difficult concept for someone to grasp.

[joshuamorton]

I'm not sure what you're getting at. Perhaps if you could translate to less-smug, the rest of us could understand.

[slovenlyrobot]

There's really not much to it, but if it's a foreign concept it may require a kind of conceptual leap. Essentially, this code worked perfectly well, and suddenly it no longer worked. From your perspective, as you quite effortlessly put it, this code is broken. For others elsewhere in more conservative parts of the world, it was not my code that broke, but the surrounding ecosystem.

There is a fabulously unending depth to explore in the chasm lying between these opposing world views. It would be more than possible to write a book on the topic and fail to cover it all, however here are some of the most important aspects, from my perspective at least:

* given a perfectly functional tool relied on heavily by its user to perform their job, and given that tool suddenly decides to change shape such that it no longer fits the user's hand without retraining, nor fits with the remainder of the user's toolset, including custom tools the user has invested in producing, the continued utility of the no-longer-functioning tool is called into question, along with a deserved reappraisal of the tool's applicability in the context of the user's original intended problem domain.

* when the reason for its reshaping is to solve what are highly important problems from the perspective of the tool, but much less so from the perspective of the average user, and that user's application of the tool to real world problems, it can no longer be said that the tool is simply an implement that may be called and relied upon at any point in future -- the tool develops a chaotic life and importance all of its own, and may choose to reshape once again at any future moment (and indeed in this case it has). It is no longer a tool, but some sentient entity demanding unpredictable ongoing costs and attention paid all of its own.

* given a tool that promises to cease functioning 'correctly' at any future moment based on its own whim, preferences, industry fashions and styles, in an ecosystem where many similar such tools exist that explicitly promise not to cease functioning over the same time period, it is a fool's errand to pick the tool that promises to externalize additional costs on the user when alternatives exist that avoid any such cost.

* given tool designers who externalize almost frivolously minor technical costs on to every user, where each 'minor' change is amplified perhaps 10000 times over and directly translates into expensive engineering time, the question is easily raised whether the philosophy of the tool is appropriate for its advertised utility, and whether continued reliance on the tool makes business sense. In economic terms, what was the cost to productivity of the retraining and re-tooling of users compared to any alleged future productivity improvement?

* had I written these scripts in bash, C# or C++, they would not have broken even remotely to the same degree. Of course these are not some completely unevolving entities either, however all take the promise of forwards compatibility deadly seriously, and it is more than possible to find 10-20 year old programs written in C++ or bash that continue functioning to the present day. From my perspective, they are therefore excellent and highly dependable tools.

[joshuamorton]

I think in your rush to appear superior, you missed the much simpler explanation. Your first comment was easy to misunderstand:

> print vs print() is what I think the parent comment was referring to.

as another person mentioned is likely what you meant, but it was easy to take your comment as meaning that you had mismatched parens somewhere, which would imply broken python2, as well as 3.

> * given a tool that promises to cease functioning 'correctly' at any future moment based on its own whim, preferences, industry fashions and styles, in an ecosystem where many similar such tools exist that explicitly promise not to cease functioning over the same time period, it is a fool's errand to pick the tool that promises to externalize additional costs on the user when alternatives exist that avoid any such cost.

This is clearly a falsehood, if the tool provides additional value. To bring things back to the topic at hand, if C++ were allowed to break ABI compatibility in very specific ways, it could be faster. stl container types are slower than many third party ones (absl, for example).

Which is to say that if you want "the best" that C++ has to offer, you have to be willing to have your libraries make backwards incompatible changes.

To jump back to python,

> given tool designers who externalize almost frivolously minor technical costs on to every user, where each 'minor' change is amplified perhaps 10000 times over and directly translates into expensive engineering time

I disagree that this happened. The examples you give are trivially fixable with 2to3. There are harder problems that 2to3 doesn't solve, but it sounds like you don't have any, so the frivolously minor technical costs are frivolously minor, and translates into running `2to3 my_code/` one time, to fix all the missing parens and most of the moved functinos.

> bash that continue functioning to the present day

I have yet to encounter a 20 year old program written in bash that functions to this day. It might be syntactically valid, but it won't do what it intended to do.

[slovenlyrobot]

I mistakenly thought you wanted clarity on my reasoning, instead it seems I've been made a fool of by providing an opportunity for you to argue a position I already understood and couldn't care less about. It's funny, this is also pretty much the reason I stopped relying on Python.

You're welcome to absorb all the externalized costs your heart desires, but in future please consider reviewing HN's rules before bandying attacks like "smug" and "superior".

[joshuamorton]

Understanding ones views doesn't imply agreeing with them. A tool is only useful if, well, it's useful. A slow C++ is less useful than a fast one. So how is it that you can claim so strongly that the value from backwards compatibility is greater than the value from speed by default?

Bluntly, if I could break the ABI to get a 10% speed boost across the board, is that not worth it?

And I'm well aware of the site guidelines. I certainly don't think asking someone to tone down the holier-than-thou in their comments is a violation of them. Just the opposite, it's encouraged. So I'll continue to ask that you do so if you choose to respond.