R devel - Sep 2012 - R crashes when printing a named numeric vector of a specific class - Bug?

Dear useR's,

today I stumbled over an interesting phenomenon: First, I created a
named numeric vector with a certain class and several attributes via the
structure() function. After that, I implemented a simple print method
for this class. When calling this function it produces an endless loop
of print calls until R crashes. :/

What is going on here? Is this a bug or have I done something completely
wrong? :)

Below is a minimal example which reproduces the behavior. Be careful
when calling foo() as this automatically calls print.bar() which causes
R to crash (at least on my PC, see further informations about my system below.)

Greetings,
Basil

--------------------------------------------------

Minimal example:

foo <- function () {
 x <- c("A" = 1.3, "B" = 0.7, "C" = -0.3)
 structure(x, class = "bar")
}

print.bar <- function (x, ...) {
  print(x, ...)
}

--------------------------------------------------

Further informations about my system:
> version
              _                            
platform       x86_64-unknown-linux-gnu     
arch           x86_64                       
os             linux-gnu                    
system         x86_64, linux-gnu            
status                                      
major          2                            
minor          15.1                         
year           2012                         
month          06                           
day            22                           
svn rev        59600                        
language       R                            
version.string R version 2.15.1 (2012-06-22)
nickname       Roasted Marshmallows         
> sessionInfo()
R version 2.15.1 (2012-06-22)
Platform: x86_64-unknown-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_US.UTF-8  
LC_COLLATE=en_US.UTF-8     LC_MONETARY=en_US.UTF-8
 [6] LC_MESSAGES=en_US.UTF-8    LC_PAPER=C                 LC_NAME=C            
LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

loaded via a namespace (and not attached):
[1] compiler_2.15.1 tools_2.15.1

print(x) in print.bar is calling print.bar again.

You need to do something like print(unclass(x))

HTH
Jeff

On Tue, Sep 11, 2012 at 9:53 AM, Basil Abou El-Komboz
<Basil.Abou-El-Komboz at stat.uni-muenchen.de>
wrote:
> Dear useR's,
>
> today I stumbled over an interesting phenomenon: First, I created a
> named numeric vector with a certain class and several attributes via the
> structure() function. After that, I implemented a simple print method
> for this class. When calling this function it produces an endless loop
> of print calls until R crashes. :/
>
> What is going on here? Is this a bug or have I done something completely
> wrong? :)
>
> Below is a minimal example which reproduces the behavior. Be careful
> when calling foo() as this automatically calls print.bar() which causes
> R to crash (at least on my PC, see further informations about my system
below.)
>
> Greetings,
> Basil
>
> --------------------------------------------------
>
> Minimal example:
>
> foo <- function () {
>  x <- c("A" = 1.3, "B" = 0.7, "C" = -0.3)
>  structure(x, class = "bar")
> }
>
> print.bar <- function (x, ...) {
>   print(x, ...)
> }
>
> --------------------------------------------------
>
> Further informations about my system:
>
>> version
>               _
> platform       x86_64-unknown-linux-gnu
> arch           x86_64
> os             linux-gnu
> system         x86_64, linux-gnu
> status
> major          2
> minor          15.1
> year           2012
> month          06
> day            22
> svn rev        59600
> language       R
> version.string R version 2.15.1 (2012-06-22)
> nickname       Roasted Marshmallows
>
>> sessionInfo()
>
> R version 2.15.1 (2012-06-22)
> Platform: x86_64-unknown-linux-gnu (64-bit)
>
> locale:
>  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8     LC_MONETARY=en_US.UTF-8
>  [6] LC_MESSAGES=en_US.UTF-8    LC_PAPER=C                 LC_NAME=C       
LC_ADDRESS=C               LC_TELEPHONE=C
> [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
> loaded via a namespace (and not attached):
> [1] compiler_2.15.1 tools_2.15.1
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel


-- 
Jeffrey Ryan
jeffrey.ryan at lemnica.com

www.lemnica.com

Le mardi 11 septembre 2012 ? 16:53 +0200, Basil Abou El-Komboz a ?crit
:
> Dear useR's,
> 
> today I stumbled over an interesting phenomenon: First, I created a
> named numeric vector with a certain class and several attributes via the
> structure() function. After that, I implemented a simple print method
> for this class. When calling this function it produces an endless loop
> of print calls until R crashes. :/
> 
> What is going on here? Is this a bug or have I done something completely
> wrong? :)
> 
> Below is a minimal example which reproduces the behavior. Be careful
> when calling foo() as this automatically calls print.bar() which causes
> R to crash (at least on my PC, see further informations about my system
below.)
> 
> Greetings,
> Basil
> 
> --------------------------------------------------
> 
> Minimal example:
> 
> foo <- function () {
>  x <- c("A" = 1.3, "B" = 0.7, "C" = -0.3)
>  structure(x, class = "bar")
> }
> 
> print.bar <- function (x, ...) {
>   print(x, ...)
> }
What is your code supposed to do exactly? ;-)

You're calling print() in your class' print.bar() function, so calling
print() on such an object will call print.bar(), which calls print(),
which calls print.bar()... In a few moments the recursion will have gone
so deep that some system limit about the stack size must be reached, and
R is killed.

If you just want to print the object as a vector, you do not need to
define any function. Or, at least, call print.default() instead of the
generic print().


My two cents
> --------------------------------------------------
> 
> Further informations about my system:
> 
> > version
>               _                            
> platform       x86_64-unknown-linux-gnu     
> arch           x86_64                       
> os             linux-gnu                    
> system         x86_64, linux-gnu            
> status                                      
> major          2                            
> minor          15.1                         
> year           2012                         
> month          06                           
> day            22                           
> svn rev        59600                        
> language       R                            
> version.string R version 2.15.1 (2012-06-22)
> nickname       Roasted Marshmallows         
> 
> > sessionInfo()
> 
> R version 2.15.1 (2012-06-22)
> Platform: x86_64-unknown-linux-gnu (64-bit)
> 
> locale:
>  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8     LC_MONETARY=en_US.UTF-8
>  [6] LC_MESSAGES=en_US.UTF-8    LC_PAPER=C                 LC_NAME=C       
LC_ADDRESS=C               LC_TELEPHONE=C
> [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       
> 
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base     
> 
> loaded via a namespace (and not attached):
> [1] compiler_2.15.1 tools_2.15.1
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

For whoever is going to troubleshoot this, I cannot reproduce this
endless-loop crash on Windows (Platform: x86_64-w64-mingw32/x64
(64-bit)).  With:
> foo <- function () {
+  x <- c("A" = 1.3, "B" = 0.7, "C" = -0.3)
+  structure(x, class = "bar")
+ }
>
> print.bar <- function (x, ...) {
+   print(x, ...)
+ }

I get:
> foo()
Error: C stack usage is too close to the limit

on R version 2.14.2 (2012-02-29) and R version 2.15.1 Patched
(2012-09-10 r60659), and
> foo()
Error: evaluation nested too deeply: infinite recursion / options(expressions=)?

on R Under development (unstable) (2012-09-10 r60659)

/Henrik

On Tue, Sep 11, 2012 at 7:53 AM, Basil Abou El-Komboz
<Basil.Abou-El-Komboz at stat.uni-muenchen.de>
wrote:
> Dear useR's,
>
> today I stumbled over an interesting phenomenon: First, I created a
> named numeric vector with a certain class and several attributes via the
> structure() function. After that, I implemented a simple print method
> for this class. When calling this function it produces an endless loop
> of print calls until R crashes. :/
>
> What is going on here? Is this a bug or have I done something completely
> wrong? :)
>
> Below is a minimal example which reproduces the behavior. Be careful
> when calling foo() as this automatically calls print.bar() which causes
> R to crash (at least on my PC, see further informations about my system
below.)
>
> Greetings,
> Basil
>
> --------------------------------------------------
>
> Minimal example:
>
> foo <- function () {
>  x <- c("A" = 1.3, "B" = 0.7, "C" = -0.3)
>  structure(x, class = "bar")
> }
>
> print.bar <- function (x, ...) {
>   print(x, ...)
> }
>
> --------------------------------------------------
>
> Further informations about my system:
>
>> version
>               _
> platform       x86_64-unknown-linux-gnu
> arch           x86_64
> os             linux-gnu
> system         x86_64, linux-gnu
> status
> major          2
> minor          15.1
> year           2012
> month          06
> day            22
> svn rev        59600
> language       R
> version.string R version 2.15.1 (2012-06-22)
> nickname       Roasted Marshmallows
>
>> sessionInfo()
>
> R version 2.15.1 (2012-06-22)
> Platform: x86_64-unknown-linux-gnu (64-bit)
>
> locale:
>  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8     LC_MONETARY=en_US.UTF-8
>  [6] LC_MESSAGES=en_US.UTF-8    LC_PAPER=C                 LC_NAME=C       
LC_ADDRESS=C               LC_TELEPHONE=C
> [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
> loaded via a namespace (and not attached):
> [1] compiler_2.15.1 tools_2.15.1
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel