Re: std::max(unsigned, size_t), amd64 and C++0x

Francis Glassborow <francis.glassborow@btinternet.com> writes:

| Gabriel Dos Reis wrote:
| > Francis Glassborow <francis.glassborow@btinternet.com> writes:
| >
| > | Pete Becker wrote:
| > | > On 2008-08-27 22:14:08 -0400, Nick Hounsome
| > | > <nick.hounsome@googlemail.com> said:
| > | >
| > | >>
| > | >> Secondly I read somewhere recently a rant about the STL implementation
| > | >> of max and why it was so complicated - It appears that for such an
| > | >> intuitively simple function, max is actually extremely difficult, if
| > | >> not impossible to get right in all cases.
| > | >
| > | > The implementation of max is not complicated at all:
| > | >
| > | > template <class T> T max(const T& t1, const T& t2) { return t1 < t2 ? t2
| > | > : t2; }
| > | >
| > | > Maybe you're thinking of a proposal to add a bunch of stuff to max that
| > | > bloated it to over 200 lines of code in order to "improve" it.
| > | >
| > |
| > | And that implementation has the problem that both arguments must be of
| > | the same type.
| >
| > What is the semantics of a max() over a pair of values of different types?
|
| Well I have no problem with wanting a max given an int value and a const
| int value.

Well, I do not see a difference a between a *value* of type int, and a
value of type const int. And for that matter, I do not see much
difference between a *value* of type T, and a value of type const T.

| I also have not problem with the semantics of:
|
| int i(0);
| short s(3);
| int i(std::max<int>(i, s));

but then when you right std::max<int>(i, s), you are NOT computing the
max of an int and a short. You're computing the max of two ints.

| So I must be missing your point.

I hope the above makes things clearer.

| >
| > | Of course we now have a fix for that problem in that the
| > | type of the parameter can be specified at the call site and so avoid the
| > | problem of implicit type deduction. That still can create surprises
| > | when porting programs that use standard typedefs such as size_t, time_t etc.
| >
| > Yeah, when and why would one want to compare size_t to a time_t?
| >
|
|
| The problem is that the literals for those are usually of type int even
| when they are not themselves synonyms for int.

Then I'm doubtful that the cure should be to introduce a max() as
proposed, as opposed to propoerly annotating those literals with the
right type.