> I have noticed that many functions contain arguments with defaults of > the form X=X.
Can you show us one (one that 'works')? Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf > Of Andrew Hoerner > Sent: Monday, December 16, 2013 9:31 AM > To: [email protected] > Subject: [R] Assigning default function arguments to themselves: Why? > > Let us suppose that we have a function foo(X) which is called inside > another function, bar(). Suppose, moreover, that the name "X" has been > assigned a value when foo is called. > > I have noticed that many functions contain arguments with defaults of > the form X=X. Call this reflexive assignment. How is foo(X=X) > different from foo(X)? Isn't the environment from which X is located > the parent environment of foo() in either case? Or if it looks first > in the environment of foo, will it not immediately pop up to the > parent frame if it is not found in foo? Are reflexive assignments just > to keep X from being positionaly assigned accidentally, or are They > doing something deeper? > > A question which is (I think) related: Is it good or bad practice, > when defining a function inside another function, to use the name of a > variable from the calling function as the argument of the called > function? > > [[alternative HTML version deleted]] > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
