BUILT-IN MATHEMATICA SYMBOL
On
On[symbol::tag]
switches on a message, so that it can be printed.
On["name"]
switches on a named group of messages.
On[s]
switches on tracing for the symbol s.
On[m1, m2, ...]
switches on several messages or message groups.
- Some messages for built-in functions are off by default, and must explicitly be switched on using On.
- In On["name"], possible named message groups include:
-
| "Compiler" | warnings associated with compiled code |
| "Graphics" | warnings associated with graphics generation |
| "Packing" | notifications associated with packed arrays |
| "Spelling" | spell-checking messages for symbol names |
| "Symbolics" | warnings associated with symbolic computation |
- $MessageGroups gives a complete list of message groups recognized by On.
- On[General::name] switches on all messages derived from General::name.
- When tracing is switched on, each evaluation of a symbol, on its own or as a function, is printed, together with the result.
- Note that the tracing information is printed when a function returns. As a result, traces of recursive functions appear in the opposite order from their calls.
- On[Assert] switches on messages associated with assertions specified by Assert.
- On[s] is equivalent to On[s::trace].
- On[] is equivalent to On[s::trace] for all symbols.
Turn on a message that is issued whenever a new symbol is created:
Now when a new symbol is created the message is issued:
| Out[2]= |  |
This turns the message back off:
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