kicad-developers team mailing list archive

[Wayne Stambaugh <stambaughw@xxxxxxxxxxx>]

On 4/8/2013 3:06 PM, Dick Hollenbeck wrote:
> Lorenzo,
> 
> 
> There was a breakdown in communications.
> 
> Were you informed of my objections to LAYER_NUM?
> 
> 
> Dick

Dick,

I thought I did pass on your comments to Lorenzo but it's been awhile so
it may have fallen thru the cracks.  If that is the case, I apologize
for the mental lapse.

Lorenzo,

If your going to use typedefs for integer types, my preference is to use
the ones defined stdint.h.  I know what a unint32_t is without having to
look up it's typedef.  I don't know what a LAYER_NUM is without grepping
the code.  Now that we have officially kicked MSVC to the curb, it is
safe to use stdint.h.

Wayne

> 
> 
> 
> 
> On 04/08/2013 01:17 PM, Lorenzo Marcantonio wrote:
>> On Mon, Apr 08, 2013 at 12:22:03PM -0500, Dick Hollenbeck wrote:
>>> We don't need a special type for each usageof an integer.
>> It's here exactly for type safety. Even pointer are integers, in fact
>> BCPL (the progenitor of C) used ints as pointer. Still some toolkit
>> force you to fit pointer into ints (which isn't even legal in C!)
>> But a layer id is *only* a layer id, you can't do math with it and so
>> on. In fact in my private branch LAYER_NUM is an enum just like
>> LAYER_MSK. In the past I fixed bugs (and comments, and variable names)
>> where reading from the code a mask would be passed when in fact it was
>> a layer id. C++11 has added features to inhibit the enum to integer
>> default promotion, just to say how much the technique is useful... would
>> you use only void* for pointers?
>>
>> Read here:
>> http://www.cprogramming.com/c++11/c++11-nullptr-strongly-typed-enum-class.html
>>
>> enums also can't take "invalid" values unless casted; that avoid checks
>> everywhere for their correctness. I have a LayerToInt for the (rare)
>> cases where such cast is needed (actually only in I/O and for user
>> interface indexed). Oh and, by the way, that made me found the evil
>> encoding of a layer pair for vias... I still have to fix it, I need to
>> study the code better for that. That's one of the reason for not
>> committing the whole LAYER_NUM modification (the other one is that I'm
>> still not happy with the enum representation).
>>
>> In some project they go to the extreme to typedef even different
>> coordinates system, i.e. logical coords are a type and physical coords
>> are another; in that way you *can't* use the wrong reference system. In
>> ADA even if you typedef to an int you get a whole different type
>> *incompatible* to an int (that's a really static type system...)
>>
>> It's more useful anyway than encapsulating a variable with public getter
>> and setter that don't do nothing special.
>>
> 
> 
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