Rationale for Ada 2012
Chapter 4: Structure and visibility
This chapter describes various improvements in
the areas of structure and visibility for Ada 2012.
Perhaps the most amazing change is that functions
may now have parameters of all modes. In earlier versions of Ada, functions
could only have parameters of mode in and so could not change
variables explicitly passed as parameters; however, they could silently
manipulate global variables in any way whatsoever. In order to ameliorate
any risks of foolishness with this new freedom, there are new rules regarding
order dependence.
There are also important improvements to incomplete
types which make them much more useful; these include completion by a
private type, their use as parameters and a new form of generic parameter.
Other improvements include a new form of use clause
and changes to extended return statements.
© 2011, 2012, 2013 John Barnes Informatics.
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