Hi,
Also assume you have a record and a hashmap that stores them. Now you
add a string to the record which turns it into a managed one and
suddenly your code will no longer work, probably resulting in subtle
bugs or memory leaks. That's /not/ what should happen for merely
adding a string. It's already bad enough that this happens with the
Pascal style I/O we don't need to have this with base container types.
For calling Free we have explicit classes. But the difference between
managed types vs. not-managed types is subtle and can change - as
mentioned above - by merely adding a field.
That is why FreePascal should merge non-managed generic classes that
have the same size when it can.
But as long as FreePascal does not do it, the user needs to do the
merging manually, with all the resulting problems. And constants
generics can be used to store the size
Best,
Benito
On 27.04.20 07:46, Sven Barth wrote:
Am 26.04.2020 um 23:42 schrieb Benito van der Zander:
Hi Sven,
It's not that simple. In principle you're right that the compiler
could try to merge more implementations, but this does not depend on
the declaration of the generic, but the use of the parameter types.
I mostly use generics for containers, especially hashmaps. They only
stores the values and never calls specific methods on them
Well, nice and well for /you/ then, but there are many more uses for
generics. And as a compiler developer I /must/ think about these cases
as well.
Not to mention that your TBaseHashMap would not work with managed
types...
That would need be handled separately. There are probably also people
who want a container that calls .free on TObject descendants.
The user should not need to care about that, especially for general
base classes.
Also assume you have a record and a hashmap that stores them. Now you
add a string to the record which turns it into a managed one and
suddenly your code will no longer work, probably resulting in subtle
bugs or memory leaks. That's /not/ what should happen for merely
adding a string. It's already bad enough that this happens with the
Pascal style I/O we don't need to have this with base container types.
For calling Free we have explicit classes. But the difference between
managed types vs. not-managed types is subtle and can change - as
mentioned above - by merely adding a field.
Regards,
Sven
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