flynn@ACF2.NYU.EDU (Susan Flynn) (02/20/88)
From: dewar@acf2.nyu.edu (Robert Dewar) Date: 17-Feb-88 23:25 EST Subject: Re: Tasking and delays, again... An interesting question in the Feldman delay test is whether it is valid for two tasks to "simultaneously" [i.e. without intermediate synchronization] write to the standard output file. It could be argued that the file object accessed is a shared variable, and that thus 9.11 makes such a program erroneous. In the case of FLOAT_IO, the variables DEFAULT_FORE etc are clearly shared variables, so you CERTAINLY cannot change one of these defaults and then use the package from some other task. If some kind of sharing is permitted, what is the rule concerning indivisibility. As far as Ada is concerned, putting a string is just as much an atomic action as putting a character, so there seems no reason to expect interruption on a character by character basis (if this seems permissible, why not interrupt after an individual vector or pixel is drawn on the output screen?)