JPG and PNG decoder

[Chris NS]

On Sunday, 17 June 2012 at 20:10:28 UTC, cal wrote:
> though I have worlds of trouble with const-ness, I will 
> endeavour to add those guarantees :)

What I usually do, unless it's just an obvious case, is write 
code without concern for const-ness, then write a thorough test 
and step through one function/whatever at a time and apply 
const/inout/pure/nothrow/etc, do any apparent refactoring, and 
check the test.  Writing the test helps me grok as many 
imaginable cases as possible, and doing it incrementally avoids 
massive "error cascades" from the compiler.