[fpc-devel] MACRO - correct syntax?

[Giuliano Colla]

Il 25/02/2018 13:55, Florian Klämpfl ha scritto:

>> To limit their use.

Well, just for sake of argument, it appears to me a rather drastic approach.

You may write other similar pages on stackoverflow, telling why 
Dereferencing is evil, Typecasting is evil, or why "Absolute" or the 
"with" construct are evil.  All of them, if misused, can lead to 
unexpected results, with code hard to read, easy to misinterpret, and 
hard to debug. Nonetheless they're part of the language, and, properly 
used, are useful programmer's tools.

Most of the drawbacks of macro arguments can be easily overcome if
a) The listing of preprocessor output is generated.
b) The preprocessor output is provided to the debugger as the actual 
program source
None of the two should require a titanic effort!

IMHO macro arguments, if properly used, may be a valid additional 
programmer tool.

E.g. Converting a C program to Pascal I had:
C code:

#define EXCH_INITIALIZER(nam) \
     {NULL,NULL,NULL,NULL,NULL,PTHREAD_MUTEX_INITIALIZER,nam}
....
EXCHANGE_DESCRIPTOR cp_ready_ex = EXCH_INITIALIZER("CP_RDY");


Lacking macro arguments, the equivalent declaration in fpc became:

cp_ready_ex: exchange_descriptor = (
  message_head : Nil;
  message_tail : Nil;
  task_head : Nil;
  task_tail : Nil;
  exchange_link : Nil;
  mutex : (__m_reserved: 0; __m_count: 0; __m_owner: Nil;__m_kind: 0;__m_lock: (__status: 0;__spinlock:0));
  name: ' CP_RDY';);

(and I had quite a number of them!)
A lot of error prone typing, just to provide the only useful 
information, i.e. the readable name of the thing.

Giuliano
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