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digitalmars.D.learn - C to D conversion for function

reply "Sumit Raja" <nnn nnn.com> writes:
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
Apr 29 2013
parent reply Timon Gehr <timon.gehr gmx.ch> writes:
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, ...);
Apr 29 2013
next sibling parent reply 1100110 <1100110 gmail.com> writes:
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.
Apr 29 2013
parent Timon Gehr <timon.gehr gmx.ch> writes:
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
}
Apr 29 2013
prev sibling parent reply "Sumit Raja" <nnn nnn.com> writes:
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?
Apr 29 2013
parent Timon Gehr <timon.gehr gmx.ch> writes:
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
Apr 29 2013