Re: Set operations on bool-vectors

[Daniel Colascione <dancol@dancol.org>]

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On 9/20/13 6:57 PM, Stefan Monnier wrote:
>> === modified file 'src/alloc.c'
>> --- src/alloc.c	2013-09-04 22:34:04 +0000
>> +++ src/alloc.c	2013-09-19 22:24:27 +0000
>> @@ -2003,6 +2003,29 @@
>>    return val;
>>  }
> 
> Could you describe the intention of the changes in alloc.c (basically,
> provide ChangeLog entries)?

Sure.  Something like this?

2013-09-21  Daniel Colascione  <dancol@dancol.org>

	* alloc.c (bool_vector_payload_bytes): New function: computes
	rounded-up payload size for a bool vector.  Always allocate
	at least size_t bytes even for a zero-size vector.
	(Fmake_bool_vector): Instead of calling Fmake_vector,
	which performs redundant initialization and argument checking,
	just call allocate_vector ourselves.  Make sure we clear any
	terminating padding to zero.
	(vector_nbytes,sweep_vectors): Use bool_vector_payload_bytes
	instead of open-coding the size calculation.

>> +       doc: /* Compute A = B ^ C, bitwise exclusive or.
> 
> Why not make it C = A ^ B and then make C optional?
> Same for other similar functions: make the destination argument optional.

Then we wouldn't be able to extend these functions to accept more than
three arguments: we wouldn't know whether the argument at the end was
another operand or a destination.


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