Function: featurep

featurep is a function defined in fns.c.

Signature

(featurep FEATURE &optional SUBFEATURE)

Documentation

Return t if FEATURE is present in this Emacs.

Use this to conditionalize execution of lisp code based on the presence or absence of Emacs or environment extensions. Use provide to declare that a feature is available. This function looks at the value of the variable features. The optional argument SUBFEATURE can be used to check a specific subfeature of FEATURE.

Probably introduced at or before Emacs version 15.

Source Code

// Defined in /usr/src/emacs/src/fns.c
{
  register Lisp_Object tem;
  CHECK_SYMBOL (feature);
  tem = Fmemq (feature, Vfeatures);
  if (!NILP (tem) && !NILP (subfeature))
    tem = Fmember (subfeature, Fget (feature, Qsubfeatures));
  return (NILP (tem)) ? Qnil : Qt;
}