Talk:Short-circuit evaluation: Difference between revisions

 

:::The turbo Pascal compiler offered a B+ or B- option to choose full or short-circuit evaluation, though I don't know of any such option in a Fortran compiler. On the one hand are the simple and clear usages for ''safe & test'' and on the other are vague murmurings about unspecified potential optimisations that might involve possible parallel execution via multiple cpus or code reordering (apparently ignoring the left-to-right rule) and any amount of hand-waving. That the modern fortran standard supports the latter does not mean its words deserve respect as holy writ from on high, especially as I have often wanted the simple scheme to work and have not seen any actual gain from the fog of vapour-optimisations. Suggestions such as .OR ELSE. sound vaguely threatening! With Compaq V. Fortran, sometimes this worked and other times not, the determinant being the precise nature of the expression and operands and vagaries of compiler choices involving register allocations or whatnnot. Although conforming to the inspecificity of the standard, I don't think this is a good thing at all. I prefer definite and understandable behaviour! Which I can then take advantage of. And such reliance becomes my mistake, since the standard's choice is not mine. Fortunately, only a few usages had to be repaired, but others, especially where the compiler happens to choose short-circuitry, may lurk. [[User:Dinosaur|Dinosaur]] ([[User talk:Dinosaur|talk]]) 12:21, 4 May 2015 (UTC)