5.3 Functions that do nothing

The following functions return fix results (or just their own argument). They can be useful in places when the syntax requires a function, but actually no functionality is required. So ReturnTrue is often used as family predicate in InstallMethod (see InstallMethod in ``Programming in GAP'').

  • ReturnTrue( ... ) F

    This function takes any number of arguments, and always returns true.

  • ReturnFalse( ... ) F

    This function takes any number of arguments, and always returns false.

  • ReturnFail( ... ) F

    This function takes any number of arguments, and always returns fail.

  • IdFunc( obj ) F

    returns obj.

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    GAP 4 manual
    February 2000