Proposal on improvement to deprecated

[Jonathan M Davis]

On Monday, October 03, 2011 15:01:13 Regan Heath wrote:
> We've already got informational warnings, warnings and errors.. why not
> just expand pragma to allow programmers to emit them on a case by case
> basis, i.e.
> 
> pragma(info, "foo is scheduled for deprecation")
> pragma(warning, "foo will be deprecated on dd/mm/yy, replace with bar")
> pragma(error, "foo has been deprecated, replace with bar")

A key problem with using pragmas for deprecation messages is the fact that 
pragma is run once when that code is compiled. So, if you want it to affect 
only people who use the deprecated function, the function has to be templated. 
So, anything which isn't templated, can't have a message. Also, it'll print 
once per template instantion, not once per use, and it won't give any line 
numbers (if it did, it would give the line number of the pragma, not where the 
function is called). The pragma messages are somewhat useful, but they're too 
general to work very well as deprecation messages.

- Jonathan M Davis