in reply to Re: LVALUE refs
in thread LVALUE refs

I haven't checked the sources, but empirical evidence made it clear...
This is one of the single most dangerous statements you can make. Perl is a programming language, not an archaeological dig or a physics experiment. Use the docs and, when they prove inadequate, read the source and check with p5p to see if what you found happens on purpose or accidentally.

Assuming "found" behaviour will persist in future versions of perl is just asking for bizarre bugs and major breakage later on--if it's not documented to work a particular way, you shouldn't assume that it will. (And yes, I know perl's docs are insufficiently rigorous to really make this statement about any of its behaviours, but the point still holds--if you had to experiment to find behaviours, and can't find reference to them in the docs, you shouldn't count on the behaviours)

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Re: Re: Re: LVALUE refs
by xmath (Hermit) on Feb 16, 2003 at 19:49 UTC
    I didn't mean to imply this was The Way, For Now And Ever.

    I simply observed perl's current behavior, and a work-around for this current behavior.

    (I don't think any docs talk about this issue)

[reply]
      Sorry, didn't mean to get cranky at you specifically. Perl's a huge language, with docs that are less than specific in spots, so lots of folks have an "experiment and find out" mentality that ultimately results in code that breaks.

      Just as a for example, if the hashing algorithm made it so that keys came out sorted by the third character, for some bizarre reason, someone would figure that out and use it in production code, which'd break if the hash function changes at some point in the future. (Perl's hashing function has already changed at least once, and it has broken some people's code)

      As one of the folks who actually implements perl, and sometimes changes the implementation, what I really hate is the potential that a change to undocumented behaviour can break user code. It's not something we like doing, and we try not to, but there's always that potential, and you're more likely to find bizarre undocumented edge cases just poking around. Hence the grumbly warning--while you may find interesting behaviour while exploring, unless it's backed by documentation you should assume that it may change in a future (or past) release.

[reply]

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