OK, when I get warnings I guess I will fix them by adding the const in the appropriate spot. At least this kind of const is not viral :)
On Sun, Oct 7, 2012 at 9:55 AM, Campbell Barton <[email protected]> wrote: > 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 _______________________________________________ Bf-committers mailing list [email protected] http://lists.blender.org/mailman/listinfo/bf-committers
