On Mon, Aug 10, 2015 at 10:18 PM, Glenn Schultz <glennmschu...@me.com> wrote: > Hi Dirk, > Thanks for your response, I get the point on return(). For me, it is a > security blanket - I just need to let that go rather than justify keeping > it. I will refactor the connections and just get comfortable without > return(). > I'm not sure you get Dirk's point about return(). He did not suggest that you avoid using return(). He provided a simple example to illustrate that code in a function body that occurs after a call to return() is not evaluated. There is nothing inherently wrong with using return(). The only thing that was wrong was how you used it.
> Thanks, > Glenn > > > On Aug 10, 2015, at 09:59 PM, Dirk Eddelbuettel <e...@debian.org> wrote: > > > On 11 August 2015 at 02:09, Glenn Schultz wrote: > | All, > | Is my function just plain wrong or is it just programming style? I use > connections because SODA (software for data analysis) recommends using > connections when working with serialized files. > > Nothing wrong with connections. Many of us use them. > > | First, after researching the use of return() - following Joshua's comment > and others I found a post on SO regarding return(). > http://stackoverflow.com/questions/11738823/explicitly-calling-return-in-a-function-or-not > > Let's try once more. The function foo() > > foo <- function() { > x <- 2 > return(x) > x <- 3 > } > > will return what value? Ie what does 'print(foo())' show? > > | Second, Hadley's point regarding the use of RDS in gz function being a > little strange. Following the help files the function is fashioned after the > following which I found in R help files: > > IIRC what Hadley was trying to say what you do _not_ need to compress before > inserting into a rds file as the rds file format compresses by default. > > In other words compression comes for free, and effortlessly so. > > Hth, Dirk > > | ## Less convenient ways to restore the object > | ## which demonstrate compatibility with unserialize() > | con <- gzfile("women.rds", "rb") > | identical(unserialize(con), women) > | close(con) > | con <- gzfile("women.rds", "rb") > | wm <- readBin(con, "raw", n = 1e4) # size is a guess > | close(con) > | identical(unserialize(wm), women) > | | With respect to the first, I understand why my function would be > considered "buggy" - that can be fixed. It is the case, generally speaking, > one does not need return() when programming in R; it is a functional > language. However, some use return() and one finds return(value) in the R > help files. Is it a strict no-no to use return()? > | | With respect to the second, The function can be refactored and reduced > to readRDS(). My question, is using gz file overkill or just plain wrong? > | What is considered "best practice"? > | | -Glenn > | | | On Aug 09, 2015, at 09:04 AM, Joshua Ulrich <josh.m.ulr...@gmail.com> > wrote: > | | On Sun, Aug 9, 2015 at 8:59 AM, Glenn Schultz <glennmschu...@me.com> > wrote: > | Hi All, > | | I use connections to open and close data folders needed by my package. > | After each function closes I get the following warnings (depending on the > | connection that has been opened). > | | 10: closing unused connection 3 > | > (/Library/Frameworks/R.framework/Versions/3.2/Resources/library/BondLab/BondData/bondlabMBS4.rds) > | | Below is the connection function that is related to the above warning: > | | > #------------------------------------------------------------------------------------ > | #' A connection function to BondData calling MBS cusps > | #' > | #' Opens a connection to the BondData folder to call MBS cusip data > | #' @param MBS.id A character string the MBS.id or cusip number current > | MBS.id is supported > | #' @export > | MBS <- function(MBS.id = "character"){ > | MBS.Conn <- gzfile(description = paste(system.file(package > | = "BondLab"), > | "/BondData/", MBS.id, ".rds", sep = ""), open > | = "rb") > | MBS <- readRDS(MBS.Conn) > | return(MBS) > | close.connection(MBS.Conn) > | } > | | I have googled this warning and it seems to be triggered when a function > | terminates and the connection is open. But, I think the connection > function > | closes the connection once the object is returned. What am I doing wrong? > | | Your call to return() exits the function, so the close.connection() > | call is never evaluated. Considering using on.exit() to close the > | connection, since it will close the connection regardless of how the > | function exits (e.g. because of an error). > | | -Glenn > | ______________________________________________ > | R-package-devel@r-project.org mailing list > | https://stat.ethz.ch/mailman/listinfo/r-package-devel > | | | | -- | Joshua Ulrich | about.me/joshuaulrich > | FOSS Trading | http://www.fosstrading.com > | ______________________________________________ > | R-package-devel@r-project.org mailing list > | https://stat.ethz.ch/mailman/listinfo/r-package-devel > > -- > http://dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org > ______________________________________________ > R-package-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-package-devel -- Joshua Ulrich | about.me/joshuaulrich FOSS Trading | www.fosstrading.com ______________________________________________ R-package-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-package-devel
