Idea for more delegations in <algorithm>
Gabriel Dos Reis
gdr@integrable-solutions.net
Wed Mar 23 17:41:00 GMT 2005
Paolo Carlini <pcarlini@suse.de> writes:
| Chris Jefferson wrote:
|
| > | Or, for some reason, we have troubles with this too? :(
| >
| > Unless I'm going mad (possible), default parameters are inserted and
| > passed by the compiler (at least on x86), so this will in fact be worse,
| > because that "0" will always be created and passed by the compiler
| > (because it might be needed for all it knows) whereas the empty classes
| > might eventually be optimised away with compiler improvements.
|
| I see, I was afraid that something like that could happen, in
| principle (have never looked myself to the actual way defaults are
| compiled)
There is always a value passed to the function -- when none is
lexically specified in the source code, the compiler uses the default
value.
The situation is slightly different for empty classes: we and the
compiler know that a value of that type is insignificant. So, it
could be safely not loaded into the argument list.
For the enable-if stuff, only we (and not the compiler) know that the
default is just a hackery artefact -- except when the function is of
course inline and inlined.
-- Gaby
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