[Qt-interest] Qt Containers (or: why I must use STL)

[Ian Thomson]

Stephen Bryant wrote:
> I'm afraid you've lost me on this one.  How is 'int' simpler than 'size_t'?
> Why are there warnings?  STL manages to have container::size_type defined
> as size_t, and I'm not seeing warnings for that on any of the platforms
> I'm building on.  Is this limited to certain systems, perhaps?

The signals and slots mechanism can only connect up like types. For that 
reason, all numeric values are 'int' to encourage compatibility between 
different signals and slots and so on. Mixing in size_t would not help here.

This idea has been carried over to the Qt container formats. As Qt is 
designed for creating GUI apps, most often the user code will be doing 
things inside (or based on) slots which are called. These slots will 
have integer parameters. Of course, passing an integer to a function 
which requires a size_t will cause a compiler warning, and vice-versa.

This is troublesome to the coder and solutions with casts don't offer 
any advantages over just using ints (you're still limited to max_int) 
and actually reduces the ability to detect bad values (e.g. asserting 
the value is not less than 0).

Cheers,
Ian.