On 09/07/2011 00:59, Max Vlasov wrote:
On Sat, Jul 9, 2011 at 3:14 AM, Martin<f...@mfriebe.de> wrote:
function CRCConstString(constref Str: string): integer;
does what you describ
Hmm, it's interesting.. Some observations:
- constref is implemented in 2.5.1, right? Unfortunately I can not
test it right now in 2.4.2, it refuses to recognize it, but I I want
to test it.
- In LCL it used only with interfaces and TGuid's, no strings or other
structures
- there are not much information about constrefs in Lazarus, several
posts, the largest part of them is yours, Martin :) so you're probably
one of the few who really understand it :)
Well the LCL can't use it, if it's trunk only (except if IFDEFed). The
LCL should compile with release fpc...
See:
http://wiki.lazarus.freepascal.org/FPC_New_Features_Trunk#Constref_parameter_modifier
- See difference to normal "const" is " that it must be passed by
reference."
- Note (same as const) it is described as: "This modifier means that the
compiler can assume that the parameter is constant"
The "assume" means that the requirement for constant-ness goes above
that what the compiler can enforce (that is: the compiler can enforce
only the local var; but constant implies the value by any means of access)
With what the compiler does today (afaik) none-constantness would not
cause any harm (yet). Unless you count it as harm (and you should) that
future FPC may (= "is allowed to") compile your code (without any
warning or hint) into an exe that behaves different.
_______________________________________________
fpc-devel maillist - fpc-devel@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-devel
