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From: "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: No warning at implicit removal of const. Was: relearning C: why
 does an in-place change to a char* segfault?
Date: Mon, 5 Aug 2024 13:35:28 -0700
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On 8/5/2024 4:03 AM, Ben Bacarisse wrote:
> "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> writes:
> 
>> On 8/4/2024 6:06 PM, Ben Bacarisse wrote:
>>> "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> writes:
>>>
>>>> On 8/2/2024 3:29 PM, Ben Bacarisse wrote:
>>>>> "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> writes:
>>>>>
>>>>>> For some reason I had a sort of a habit wrt const pointers:
>>>>>>
>>>>>> (experimental code, no ads, raw text...)
>>>>>> https://pastebin.com/raw/f52a443b1
>>>>>>
>>>>>> ________________________________
>>>>>> /* Interfaces
>>>>>> ____________________________________________________________________*/
>>>>>> #include <stddef.h>
>>>>>>
>>>>>>
>>>>>> struct object_prv_vtable {
>>>>>>      int (*fp_destroy) (void* const);
>>>>>> };
>>>>>>
>>>>>>
>>>>>> struct device_prv_vtable {
>>>>>>      int (*fp_read) (void* const, void*, size_t);
>>>>>>      int (*fp_write) (void* const, void const*, size_t);
>>>>>> };
>>>>> Why?  It seems like an arbitrary choice to const qualify some pointer
>>>>> types and some pointed-to types (but never both).
>>>>
>>>> I just wanted to get the point across that the first parameter, aka, akin
>>>> to "this" in C++ is a const pointer. Shall not be modified in any way shape
>>>> or form. It is as it is, so to speak:
>>>>
>>>> void foo(struct foobar const* const self);
>>>>
>>>> constant pointer to a constant foobar, fair enough?
>>> No.  If you intended a const pointer to const object why didn't you
>>> write that?  My point was that the consts seems to be scattered about
>>> without any apparent logic and you've not explained why.
>>>
>>>>>> ;^)
>>>>> Does the wink mean I should not take what you write seriously?  If so,
>>>>> please ignore my question.
>>>>
>>>> The wink was meant to show my habit in basically a jestful sort of
>>>> way.
>>> Your habit of what?
>>
>> To write the declaration with names and the const access I want, so:
>>
>> extern void (void const* const ptr);
>>
>> void (void const* const ptr)
>> {
>>     // ptr is a const pointer to a const void
>> }
> 
> I don't think you are following what I'm, saying.  If you think there
> might be some value in finding out, you could as a few questions.  I
> won't say it again ;-)
> 

I must be misunderstanding you. My habit in such code was to always make 
the "this" pointer wrt some of my "object" oriented code a const 
pointer. This was always the first parameter:

extern void foobar(void const* const ptr);

or

extern void foobar(void* const ptr);


Actually, I used the name of self for a while.


extern void foobar(void const* const self);
extern void foobar(void* const self);