AIPS++ Developers' Notes

Version 1.9 Build 000

News

Documentation Issues

Please avoid the use of \newcommand in your .help files. The better option is to use \renewcommand. A standard set of AIPS++ definitions maybe found in code/doc/texinputs.dir/aips2defs.tex.

General Problems

Default arguments in .cc files are not allowed. Please only put default arguments in you .h files.
Forward declarations in header files are valid only if they forward declare pointers or references.
Please use const expressions when declaring an array like:
```
Double eh[n];
```
n must be a const expression, if it's non-const you must do:
```
Double *eh = new Double[n];
```
The egcs/gnu compiler is notorious for allowing non-const array declarations.

Known SGI compiler gotchas

consts must always be assigned after non consts, so always do:

const int a;
      int b;

a = b = 0;

rather than

b = a = 0;

If an argument is declared const *&, the SGI compiler expects the variable you put in the argument to be a const ptr.
Constructs of the type myclass < T > a = 1.0 cause troubles as the SGI compiler isn't very smart about temporary conversions.
Conversion involving const numbers to Floats need to be done explicitly. Something line MyClass < Float > a = 1.0; fails cause it can't cast the 1.0 to a float. Use MyClass < Float > a = 1.0f;
Problems with arguments not being promoted, i.e. float to double, especially for min and max. The following code snippet fails on the SGI
```
Float x;

Double maxX = max(x, 1.0)
```
The SGI complains that there is no declaration for max(float, double). It basically fails to promote float to double. Please try and keep the arguments the same type for max and min, i.e.
```
Float x;

Double maxX = max(x, 1.0f)
```

tMuvw failed for some obsure reason on the following construct

 cout << "Pos constructor:" << MVuvw(x, x2) << endl;         

where x and x2 are MVuvw's

If you have an ImageInterface and pass it as an argument to a method/function that expects a Lattice, SubLattice, or MaskedLattice, you will need to call the latticeCast member function. The SGI compiler is too dumb to figure this out.
If you assign const pointers to non-const pointer you need to cast away the constness.
Make sure inlined functions are defined in your .h file and not the .cc file.
Statements like flag ? delete pointer : 0; fail with the SGI compiler, please use an if statement.

Send comments or questions about AIPS++ to aips2-requests@nrao.edu