On Mon, Oct 8, 2012 at 1:26 AM, Jason Wilkins <[email protected]> wrote: > I probably would not notice except that it is done inconsistently and > I get lots of warnings. I tend to fix things by removing the const > though. > > Another thing I noticed was returning a const pointer from a function > but then expecting to free it using 'free'. Dynamically allocated > memory is not 'const' for the purposes of 'free'. It would probably > be better to cast away the const inside a special function instead of > asking the user to use a raw 'free'. (or just not use const). agree, const can be a bit of a pain like this.
> I'm all for using const, but I really question if making primitive > arguments const is more trouble than it is worth. I mean, to follow > through on it would be a huge task. It only generates a warning (no > error) when done inconsistently and if you change your mind now you > have to make a change in two places instead of one. You dont need to follow it though, if a dev wants to use it, they can, when done inconsistently it wont give warnings in GCC - but this stuff is really issue with multi-platform dev, it happens in other areas too - I often wake up to find blender wont compile because of an error in some commit from a dev with a different environment (-Werror helps here too :) ). you can correct warnings, or mail some other dev to fix, last I compiled on MSVC I didnt see any warnings like this though (a few weeks back). > To me this is a C programmers version of those people who have to turn > a light switch on and off a prime number of times. > > Reason #5 would be that it is just cluttered and ugly. It decreases > readability instead of enhancing it. It reminds me of when I had a > phase where I wanted to add 'struct' to everything so that people knew > that, yes, this is a struct. think this comes down to personal preference, if you think its not warranted, don't add it to your code. > I guess detecting stack corruption does not seem like a plus to me > because my environment does this very aggressively without help > (MSVC). Its no protection against stack corruption, It just means you know the var wont change under normal conditions, if it does change that something exceptional/wrong is happening. > On Sun, Oct 7, 2012 at 8:22 AM, Campbell Barton <[email protected]> wrote: >> On Sun, Oct 7, 2012 at 8:25 PM, Jason Wilkins <[email protected]> >> wrote: >>> If I had a function with the prototype: foo(int bar) >>> >>> It may be tempting to declare the it as: foo(const int bar) >>> >>> The reason would be that bar is not modified inside of foo, so by >>> declaring it this way we prevent ourselves from accidentally modifying >>> it. >>> >>> This is not idiomatic C, and for good reasons. >>> >>> 1) We use 'const' on pointers to indicate that we are not going to >>> modify what is pointed at, when a programmer sees 'const int' it is >>> momentarily confusing because we expect 'const int*' >>> >>> 2) This exposes internal details of the function to the outside world. >>> The fact that 'bar' is const in this case is not actually a part of >>> the interface of that function. >>> >>> 3) If we change our minds later and actually do want to modify the >>> copy of 'bar' inside the function then we have to change the interface >>> again, but as per #2 it actually has nothing to do with the user of >>> 'foo' >>> >>> 4) It is just not idiomatic. Looking at it is like listening to a >>> foreigner speak your native language in "creative" ways. >>> >>> I have not figured out who is doing this, but please stop :) >> >> I've been doing this and Im not convinced its a bad thing, in some >> functions its a good hint that a var is `fixed` and shouldn't be >> changed. >> If a dev wants to change it they can just remove the `const` but it >> means they think twice before doing it (as in - maybe there is a good >> reason it shouldn't be changed). >> >> The main reason I like to have this sometimes is when debugging you >> know for sure a var wont change, if it does - its a buffer overflow or >> something exceptional. >> Often its not really an issue - but there are cases it can help verify >> whats going on when reading the function. >> >> That the `const` gets in the header is a little inconvenience if it >> changes often - but IMHO changing those is rare enough that its not an >> issue. >> _______________________________________________ >> Bf-committers mailing list >> [email protected] >> http://lists.blender.org/mailman/listinfo/bf-committers > _______________________________________________ > Bf-committers mailing list > [email protected] > http://lists.blender.org/mailman/listinfo/bf-committers -- - Campbell _______________________________________________ Bf-committers mailing list [email protected] http://lists.blender.org/mailman/listinfo/bf-committers
