Unsigned byte sidestep - introduction

[Reinier Zwitserloot]

Combining 0hFF and the (+) cast seems nicer, somehow, than coming up  
with a bunch of new random letters for byte and short literals.

  --Reinier Zwitserloot



On Mar 25, 2009, at 09:43, Bruce Chapman wrote:

> Hello all,
>
>
> I am about to submit 3 proposals which are related.
>
> This email serves to background the 3 proposals
>
> The proposals are my best attempt at solving the no unsigned byte
> dilemma in a way that fits the existing language.
>
> After much thought I have identified two root issues which cause me to
> want unsigned byte.
>
>
> The proposals address these issues without actually add unsigned  
> bytes.
>
> The first root issue is the lack of byte size literals, so byte  
> literals
> must be formed by a narrowing conversion (cast) from an int literal.  
> The
> cast in this case can increase the code by over 100% and is  
> particularly
> onerous when populating byte arrays with fixed values, often during
> testing but in other cases as well.
>
> I have two competing proposals for byte (and short) integer literals
> with different advantages and disadvantages. These are mutually
> exclusive proposals (but under the coin rules they can't really  
> refer to
> each other - hence this email).  One of these has a nicer syntax at  
> the
> expense of a more complex specification and narrower focus (it doesn't
> support decimal byte literals).
>
>
> The second root issue is the automatic widening conversion to int
> whenever a byte field or variable is used in an expression. It is  
> not so
> much the widening, but the implicit sign extend which causes problems
> which bite when least expected. The third proposal adds an operator
> (cast like operator) to convert byte (and short) to int with zero  
> extend
> to reduce the pain of the second issue.
>
> Here is an example showing some of the present traps.
>
> byte b = (byte)0x80;  // cast needed because 0x80 is int and wont fit
>                       // in signed bit
> assert b == 0x80; // throw AssertionError because == causes the value
>                   // of b to be converted to int value 0xFFFFFF80
>
>
>
> Here are the google doc references, I'll post content soon.
>
> Auto Typing Hexadecimal and Binary Integer Literals : 0hFF
> http://docs.google.com/Doc?id=dcvp3mkv_125ww5tct
>
> Byte and Short Integer Literals (new type suffixes) : 0xFFy
> http://docs.google.com/Doc?id=dcvp3mkv_0fvz5gx7b
>
>
> Unsigned Integer Widening Operator : (+)
> http://docs.google.com/Doc?id=dcvp3mkv_2k39wt5gf
>
>
> Bruce
>