5.9.8 Condition Macros

There are a few condition macros expanding to a list of other conditions:


Expands to [show(print),command(proceed)]


Expands to [show(silent),command(proceed)]


Expands to [show(print),command(ask)]

The user can also define condition macros using the hook predicate below.

breakpoint_expansion(+Macro, -Body)   hook,development
user:breakpoint_expansion(+Macro, -Body)

This predicate is called with each (non-composite) breakpoint test or action, as its first argument. If it succeeds, the term returned in the second argument (Body) is substituted for the original condition. The expansion is done at the time the breakpoint is added.

Note that Body can be composite, but it cannot be of form Tests-Actions. This means that the whole Body will be interpreted as being in either the test or the action part, depending on the context.

The built-in breakpoint conditions cannot be redefined using this predicate. See mpg-ref-breakpoint_expansion.

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