How can a method for a new class refer to the basic function it's replacing?
Suppose I want to create a method for a class I've created, but I don't have access to the code of the original function - I just want to build on top of it. Just to give a simple example that doesn't actually do anything:
x1<-1
class(x1)<-c("myclass",class(x1))
print.myclass<-function(x) {
x<-paste0(x,"foobar")
print(x)
}
print(x1)
If I try to run the last line, it throws the function into a loop and R eventually crashes. The solution I found was to add a line to the function that strips the new class name from x before passing it to the original function:
print.myclass<-function(x) {x<-paste0(x,"foobar"); class(x)<-class(x)[-1]; print(x)}
Is there a better/best practice way to do it?
r function class methods
asked Nov 22 '18 at 15:50
iodiod
4,2172723
add a comment |
Suppose I want to create a method for a class I've created, but I don't have access to the code of the original function - I just want to build on top of it. Just to give a simple example that doesn't actually do anything:
x1<-1
class(x1)<-c("myclass",class(x1))
print.myclass<-function(x) {
x<-paste0(x,"foobar")
print(x)
}
print(x1)
If I try to run the last line, it throws the function into a loop and R eventually crashes. The solution I found was to add a line to the function that strips the new class name from x before passing it to the original function:
print.myclass<-function(x) {x<-paste0(x,"foobar"); class(x)<-class(x)[-1]; print(x)}
Is there a better/best practice way to do it?
r function class methods
asked Nov 22 '18 at 15:50
iodiod
4,2172723
add a comment |
Suppose I want to create a method for a class I've created, but I don't have access to the code of the original function - I just want to build on top of it. Just to give a simple example that doesn't actually do anything:
x1<-1
class(x1)<-c("myclass",class(x1))
print.myclass<-function(x) {
x<-paste0(x,"foobar")
print(x)
}
print(x1)
If I try to run the last line, it throws the function into a loop and R eventually crashes. The solution I found was to add a line to the function that strips the new class name from x before passing it to the original function:
print.myclass<-function(x) {x<-paste0(x,"foobar"); class(x)<-class(x)[-1]; print(x)}
Is there a better/best practice way to do it?
r function class methods
asked Nov 22 '18 at 15:50
iodiod
4,2172723
Suppose I want to create a method for a class I've created, but I don't have access to the code of the original function - I just want to build on top of it. Just to give a simple example that doesn't actually do anything:
x1<-1
class(x1)<-c("myclass",class(x1))
print.myclass<-function(x) {
x<-paste0(x,"foobar")
print(x)
}
print(x1)
If I try to run the last line, it throws the function into a loop and R eventually crashes. The solution I found was to add a line to the function that strips the new class name from x before passing it to the original function:
print.myclass<-function(x) {x<-paste0(x,"foobar"); class(x)<-class(x)[-1]; print(x)}
Is there a better/best practice way to do it?
r function class methods
r function class methods
asked Nov 22 '18 at 15:50
iodiod
4,2172723
asked Nov 22 '18 at 15:50
iodiod
4,2172723
edited Nov 22 '18 at 18:56
iod
asked Nov 22 '18 at 15:50
iodiod
4,2172723
asked Nov 22 '18 at 15:50
iodiod
4,2172723
asked Nov 22 '18 at 15:50
iodiod
4,2172723
4,2172723
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
I think your problem is that you create an infinite loop: print(print(...).
I don't know what you want to achieve but this might be what you are looking for:
x1 <- 1
class(x1) <- c("myclass",class(x1))
print.myclass <- function(x) print.default(x)
print(x1)
Perhaps you might want to look here
BTW: I don't think your solution really solves the problem. You just delete your new class entry which causes print not to use print.myclass.
For details see Hadley
answered Nov 22 '18 at 18:46
ChristophChristoph
3,02222044
Ah! I didn't realize function.default is a thing. Does that work for any function with methods? If so, that will resolve my issue.
– iod
Nov 22 '18 at 18:48
I think this is a general concept. See also the comment here
– Christoph
Nov 22 '18 at 18:51
To your BTW - my actual function makes some calculations on my object, but ultimately I want to run it through the default function (imagine if before passing x1 to print default, it doespaste0(x,"foobar")).
– iod
Nov 22 '18 at 18:54
Ok. I think, this is really the concept. See my edit and the link...
– Christoph
Nov 22 '18 at 18:55
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
I think your problem is that you create an infinite loop: print(print(...).
I don't know what you want to achieve but this might be what you are looking for:
x1 <- 1
class(x1) <- c("myclass",class(x1))
print.myclass <- function(x) print.default(x)
print(x1)
Perhaps you might want to look here
BTW: I don't think your solution really solves the problem. You just delete your new class entry which causes print not to use print.myclass.
For details see Hadley
answered Nov 22 '18 at 18:46
ChristophChristoph
3,02222044
Ah! I didn't realize function.default is a thing. Does that work for any function with methods? If so, that will resolve my issue.
– iod
Nov 22 '18 at 18:48
I think this is a general concept. See also the comment here
– Christoph
Nov 22 '18 at 18:51
To your BTW - my actual function makes some calculations on my object, but ultimately I want to run it through the default function (imagine if before passing x1 to print default, it doespaste0(x,"foobar")).
– iod
Nov 22 '18 at 18:54
Ok. I think, this is really the concept. See my edit and the link...
– Christoph
Nov 22 '18 at 18:55
add a comment |
I think your problem is that you create an infinite loop: print(print(...).
I don't know what you want to achieve but this might be what you are looking for:
x1 <- 1
class(x1) <- c("myclass",class(x1))
print.myclass <- function(x) print.default(x)
print(x1)
Perhaps you might want to look here
BTW: I don't think your solution really solves the problem. You just delete your new class entry which causes print not to use print.myclass.
For details see Hadley
answered Nov 22 '18 at 18:46
ChristophChristoph
3,02222044
Ah! I didn't realize function.default is a thing. Does that work for any function with methods? If so, that will resolve my issue.
– iod
Nov 22 '18 at 18:48
I think this is a general concept. See also the comment here
– Christoph
Nov 22 '18 at 18:51
To your BTW - my actual function makes some calculations on my object, but ultimately I want to run it through the default function (imagine if before passing x1 to print default, it doespaste0(x,"foobar")).
– iod
Nov 22 '18 at 18:54
Ok. I think, this is really the concept. See my edit and the link...
– Christoph
Nov 22 '18 at 18:55
add a comment |
I think your problem is that you create an infinite loop: print(print(...).
I don't know what you want to achieve but this might be what you are looking for:
x1 <- 1
class(x1) <- c("myclass",class(x1))
print.myclass <- function(x) print.default(x)
print(x1)
Perhaps you might want to look here
BTW: I don't think your solution really solves the problem. You just delete your new class entry which causes print not to use print.myclass.
For details see Hadley
answered Nov 22 '18 at 18:46
ChristophChristoph
3,02222044
I think your problem is that you create an infinite loop: print(print(...).
I don't know what you want to achieve but this might be what you are looking for:
x1 <- 1
class(x1) <- c("myclass",class(x1))
print.myclass <- function(x) print.default(x)
print(x1)
Perhaps you might want to look here
BTW: I don't think your solution really solves the problem. You just delete your new class entry which causes print not to use print.myclass.
For details see Hadley
answered Nov 22 '18 at 18:46
ChristophChristoph
3,02222044
edited Nov 22 '18 at 18:54
answered Nov 22 '18 at 18:46
ChristophChristoph
3,02222044
answered Nov 22 '18 at 18:46
ChristophChristoph
3,02222044
answered Nov 22 '18 at 18:46
ChristophChristoph
3,02222044
3,02222044
Ah! I didn't realize function.default is a thing. Does that work for any function with methods? If so, that will resolve my issue.
– iod
Nov 22 '18 at 18:48
I think this is a general concept. See also the comment here
– Christoph
Nov 22 '18 at 18:51
To your BTW - my actual function makes some calculations on my object, but ultimately I want to run it through the default function (imagine if before passing x1 to print default, it doespaste0(x,"foobar")).
– iod
Nov 22 '18 at 18:54
Ok. I think, this is really the concept. See my edit and the link...
– Christoph
Nov 22 '18 at 18:55
add a comment |
Ah! I didn't realize function.default is a thing. Does that work for any function with methods? If so, that will resolve my issue.
– iod
Nov 22 '18 at 18:48
I think this is a general concept. See also the comment here
– Christoph
Nov 22 '18 at 18:51
To your BTW - my actual function makes some calculations on my object, but ultimately I want to run it through the default function (imagine if before passing x1 to print default, it doespaste0(x,"foobar")).
– iod
Nov 22 '18 at 18:54
Ok. I think, this is really the concept. See my edit and the link...
– Christoph
Nov 22 '18 at 18:55
Ah! I didn't realize function.default is a thing. Does that work for any function with methods? If so, that will resolve my issue.
– iod
Nov 22 '18 at 18:48
Ah! I didn't realize function.default is a thing. Does that work for any function with methods? If so, that will resolve my issue.
– iod
Nov 22 '18 at 18:48
I think this is a general concept. See also the comment here
– Christoph
Nov 22 '18 at 18:51
I think this is a general concept. See also the comment here
– Christoph
Nov 22 '18 at 18:51
To your BTW - my actual function makes some calculations on my object, but ultimately I want to run it through the default function (imagine if before passing x1 to print default, it does
paste0(x,"foobar")).– iod
Nov 22 '18 at 18:54
To your BTW - my actual function makes some calculations on my object, but ultimately I want to run it through the default function (imagine if before passing x1 to print default, it does
paste0(x,"foobar")).– iod
Nov 22 '18 at 18:54
Ok. I think, this is really the concept. See my edit and the link...
– Christoph
Nov 22 '18 at 18:55
Ok. I think, this is really the concept. See my edit and the link...
– Christoph
Nov 22 '18 at 18:55
add a comment |
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