CODEWITHSUNDEEP
wolfram-mathematica
nilo de roock
nilo de roock

Reputation: 4157

Mathematica: How to check if no argument is supplied to a function?

How to check if no argument is supplied to a function?

For example, if I have:

  f[x_Integer]:=1
  f[x_]:=Message[errm::err, x]

and I call f with no argument:

   f[]

'nothing happens', I want to force a specific (error-)condition.

( Background: I am making MUnit tests for packages and OO-System classes. )

Upvotes: 8

Views: 826

Answers (2)

Leonid Shifrin
Leonid Shifrin

Reputation: 22579

As an alternative to explicitly listing the zero-args possibility, you can do

f[x_Integer] := 1
f[args___] := (Message[errm::err, {args}];$Failed);

which would also catch the error cases of several passed arguments (assuming that it is an error).

Upvotes: 11

acl
acl

Reputation: 6520

This?

f[x_Integer] := 1
f[x_] := Message[errm::err, x]
f[] := Message[errm::err]

Upvotes: 10

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