Am 01.02.2023 um 11:30 schrieb Bart via fpc-devel:
I thought that constref would be OK for that (the word constref suggests to me tah the paramter will be treated (by me) to be a constant, and that it shall be passed by reference in all cases, whereas with a const parameter the compiler decides upon the best way to pass it: by value or by reference). I tried to find documentation for constref, but all I could find was: https://wiki.freepascal.org/FPC_New_Features_2.6.0#Constref_parameter_modifier There it says: "Note that in general, it should only be used for interfacing with external code or when writing assembler routines."
“constref” is guaranteed to pass the parameter by reference. And the compiler will ensure that it can't be modified as reasonably possible (as with “const” there are ways to circumvent this, e.g. by passing around a pointer to the parameter, but the general cases are covered).
(B.t.w.: Where can I find the official documentation on constref?)
There is no full documentation for that parameter modifier (someone might want to file a bug report for that), but the documentation for “const” ( https://www.freepascal.org/docs-html/current/ref/refsu67.html#x183-20700014.4.4 ) contains this:
=== doc begin ===Contrary to Delphi, no assumptions should be made about how const parameters are passed to the underlying routine. In particular, the assumption that parameters with large size are passed by reference is not correct. For this the constref parameter type should be used, which is available as of version 2.5.1 of the compiler.
=== doc end === Regards, Sven
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