string literal as const var parameter

Adriaan van Os gpc at microbizz.nl
Wed Jun 27 15:06:16 CEST 2012


> Prof. A Olowofoyeku (The African Chief) wrote:
>> On 27 Jun 2012 at 11:47, Adriaan van Os wrote:
>> 
>> [...]
>>> const var parameters were introduced to interface with external (C)
>>> routines where (1) the API requires that the parameter is passed by
>>> reference and (2) passing a constant as actual parameter should be
>>> allowed. For normal use, const parameters can be used.
>> 
>> Don't const parameters comply with both conditions?
> 
> No, with const parameters, the compiler decides what is more efficient, by reference or by value. 
> For small sized parameters, by reference is more efficient. So, an integer const (and probably a 
> real const) parameter will be passed by value, which could conflict with the ABI of an external (C) 
> routine.

Of course, I intended to say "For small sized parameters, by value is more efficient."

Regards,

Adriaan van Os




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