[D-runtime] dup attributes?

[Sean Kelly]

Concatenation doesn't preserve bit flags?  Like if I do this:

mystr ~= "a" ~ "b";

You're saying that it's possible for the bits set on mystr to be lost?

On Aug 4, 2010, at 10:19 AM, Steve Schveighoffer wrote:

> One more thing -- concatenation suffers from the same problem.  This one might 
> be much harder to swallow since you may have to do N flag lookups.
> 
> -Steve
> 
> 
> 
> ----- Original Message ----
>> From: Steve Schveighoffer <schveiguy at yahoo.com>
>> To: d-runtime <d-runtime at puremagic.com>
>> Sent: Wed, August 4, 2010 8:32:38 AM
>> Subject: [D-runtime] dup attributes?
>> 
>> Currently, in the array runtime code, all appends and length settings copy the 
> 
>> BlkAttr attributes from the existing block to the new block.  This is  
>> important 
>> 
>> if you set block attributes other than the default, or you are  appending to a 
> 
>> block which is currently typed differently than what it was  when allocated.
>> 
>> However, the one function which does *not* do this is  dup.  dup uses the 
>> typeinfo to determine the block attributes,  including the NO_SCAN flag.
>> 
>> I think it should copy the attributes like  all the other functions do.  
>> However, 
>> 
>> there is one caveat to  this.  Currently dup doesn't look up the block 
>> attributes 
>> 
>> of the  existing data, because it doesn't have to.  So changing dup to copy the 
>> 
>> attributes would slow down dup a bit because in addition to allocating a new 
>> block, it must look up the flags for the old block.
>> 
>> What do you guys  think?
>> 
>> -Steve
>> 
>> 
>> 
>> 
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> 
> 
> 
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