Re: [Texmacs-dev] Re: TeXmacs port to IRIX

[Philipp Tomsich]

On Tue, 14 Jan 2003 address@hidden wrote:

> Also, on non-GNU compiler the default debugging options should
> probably be -g instead of -ggdb. What is the option to get the most
> debugging information out of your compiler?

It's "-g3"

> I think then that it may be interesting to factor-out the
> implementation of 'fast_array' to use stack allocation when available.
> I thought of using compile-time dispatch, but that does not help.
> Instead we may use a macro (yuck!).
>
>   #if CONFIG_USE_VLA
>   #define VARIABLE_LENGTH_ARRAY(TYPE,NAME,NUMBER) TYPE NAME[NUMBER]
>   #else
>   #define VARIABLE_LENGTH_ARRAY(TYPE,NAME,NUMBER) fast_array<TYPE> 
> NAME(NUMBER);
>   #endif
>
>   template<class T> class fast_array<T> {
>     T *a;
>   public:
>     inline fast_array(int n) { this->a = new T[n]; }
>     inline T& operator[] (const int i) { return this->a[i]; }
>     inline ~fast_array() { delete[] this->a; }
>   };
>
> Used as
>
>   VARIABLE_LENGTH_ARRAY(char, data, byte_width * h);
>
> Instead of
>
>   char data [byte_width * h];
>
> That way we get all the speed we can, without cluttering the code with
> ifdefs and gotos (YUCK!!!).

I've actually started work on a similar macro just a few minutes ago... I
too wanted to get rid of the gotos. I'll fix something up that uses these (or
similar macros).

> I am unsure that is really a compiler problem, and unsure the fix is
> right. For the record, the original code looks like:
>
>    tree** rs= new (tree*)[nr_rows];

> What is the actual error you are getting from your compiler?

cc-1140 CC: ERROR File = ./Edit/Modify/edit_table.cc, Line = 554
  A value of type "tree *" cannot be used to initialize an entity of type
          "tree **".

    tree** cs= new (tree*)[nr_rows];
               ^

1 error detected in the compilation of "./Edit/Modify/edit_table.cc".
~

> Actually it seems that tree*[nr_rows] effectively means 'array of
> nr_rows pointers to tree'. So the following is correct:
>
>   tree** rs= new tree*[nr_rows];
>
> A similar example is given in section 8.1 [dcl.name].

Leaving off the parathesis gives the expected result. Thanks, you're right
about this.

--phil.