Hi,

I wanted some help in converting this

void av_log_ask_for_sample(void *avc, const char *msg, ...) av_printf_format(2, 3);

from C to D.

I don't know what it means or is called in C to start with so I am a bit lost on what to search for.

Thanks

Sumit

On 04/29/2013 12:57 PM, Sumit Raja wrote:
> Hi,
>
> I wanted some help in converting this
>
> void av_log_ask_for_sample(void *avc, const char *msg, ...)
> av_printf_format(2, 3);
>
> from C to D.
>
> I don't know what it means or is called in C to start with so I am a bit
> lost on what to search for.
>
> Thanks
>
> Sumit

av_printf_format is a preprocessor macro that expands to a built-in compiler attribute which enables compile-time printf-style format string checking. There is no support for such a feature in any D compiler.

You want

void av_log_ask_for_sample(void* avc, const(char)* msg, ...);


In case you want to preserve the attribute:

struct av_printf_format{ int fmtpos, attrpos; }

@av_printf_format(2, 3) void av_log_ask_for_sample(void* avc, const(char)* msg, ...);

On 04/29/2013 06:50 AM, Timon Gehr wrote:
> On 04/29/2013 12:57 PM, Sumit Raja wrote:
>> Hi,
>>
>> I wanted some help in converting this
>>
>> void av_log_ask_for_sample(void *avc, const char *msg, ...)
>> av_printf_format(2, 3);
>>
>> from C to D.
>>
>> I don't know what it means or is called in C to start with so I am a bit lost on what to search for.
>>
>> Thanks
>>
>> Sumit
> 
> av_printf_format is a preprocessor macro that expands to a built-in compiler attribute which enables compile-time printf-style format string checking. There is no support for such a feature in any D compiler.
> 
> You want
> 
> void av_log_ask_for_sample(void* avc, const(char)* msg, ...);
> 
> 
> In case you want to preserve the attribute:
> 
> struct av_printf_format{ int fmtpos, attrpos; }
> 
> @av_printf_format(2, 3) void av_log_ask_for_sample(void* avc,
> const(char)* msg, ...);
> 

What is the difference between const(char)*, and const(char*)?  I have
seen them used pretty much interchangeably...

Are they? Somehow I don't think they are.

On 04/29/2013 02:17 PM, 1100110 wrote:
> ...
> What is the difference between const(char)*, and const(char*)?  I have
> seen them used pretty much interchangeably...
>
> Are they? Somehow I don't think they are.
>

Variables of type const(char)* can be mutated, while const(char*) cannot be.

void main(){
    const(char)* a = "123".ptr;
    *a = 2;        // error
    a = "456".ptr; // ok
    const(char*) b = "123".ptr;
    *b = 2;        // error
    b = "456".ptr; // error
}

On Monday, 29 April 2013 at 11:50:21 UTC, Timon Gehr wrote:

> In case you want to preserve the attribute:
>
> struct av_printf_format{ int fmtpos, attrpos; }
>
> @av_printf_format(2, 3) void av_log_ask_for_sample(void* avc, const(char)* msg, ...);

Thanks. What does @av_printf_format(2, 3) do to the function?

On 04/29/2013 02:24 PM, Sumit Raja wrote:
> On Monday, 29 April 2013 at 11:50:21 UTC, Timon Gehr wrote:
>
>> In case you want to preserve the attribute:
>>
>> struct av_printf_format{ int fmtpos, attrpos; }
>>
>> @av_printf_format(2, 3) void av_log_ask_for_sample(void* avc,
>> const(char)* msg, ...);
>
> Thanks. What does @av_printf_format(2, 3) do to the function?
>

Nothing except attaching a piece of data to it

http://dlang.org/attribute.html#UserDefinedAttribute