| Title: | Helper Functions for Class Object-Oriented Programming |
|---|---|
| Description: | Helper functions for coding object-oriented programming with a focus on R6. Includes functions for assertions and testing, looping, and re-usable design patterns including Abstract and Decorator classes. |
| Authors: | Raphael Sonabend [aut, cre] |
| Maintainer: | Raphael Sonabend <[email protected]> |
| License: | MIT + file LICENSE |
| Version: | 0.2.0 |
| Built: | 2024-09-10 02:54:10 UTC |
| Source: | https://github.com/xoopR/ooplah |
Creates an abstract R6 class by placing a thin wrapper around R6::R6Class which causes an error to be thrown if the class is directly constructed instead of one of its descendants.
An abstract class is a class that cannot be constructed directly. Instead they are used to define common fields/methods for child classes that inherit from them.
All arguments of R6::R6Class can be used as usual, see full details at R6::R6Class.
Gamma, E., Helm, R., Johnson, R., & Vlissides, J. (1996). Design Patterns: Elements of Reusable Software. Addison-Wesley Professional Computing Series (p. 395).
library(R6) ab <- AbstractClass("abstract", public = list(hello = "Hello World")) ## Not run: # errors ab$new() ## End(Not run) child <- R6Class("child", inherit = ab) child$new()$hellolibrary(R6) ab <- AbstractClass("abstract", public = list(hello = "Hello World")) ## Not run: # errors ab$new() ## End(Not run) child <- R6Class("child", inherit = ab) child$new()$hello
Simple wrapper around decorator$new(object, exists)
decorate(object, decorators, exists = c("skip", "error", "overwrite"), ...)decorate(object, decorators, exists = c("skip", "error", "overwrite"), ...)
object |
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decorators |
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exists |
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... |
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library(R6) ## Define decorators dec1 <- DecoratorClass("dec1", public = list(goodbye = "Goodbye World")) dec2 <- DecoratorClass("dec2", public = list(goodbye2 = "Goodbye World 2")) oop <- ooplah$new() oop$goodbye dec_oop <- decorate(oop, c(dec1, dec2)) dec_oop$goodbye dec_oop$goodbye2 ## Equivalently oop <- ooplah$new() decorate(oop, c("dec1", "dec2"))library(R6) ## Define decorators dec1 <- DecoratorClass("dec1", public = list(goodbye = "Goodbye World")) dec2 <- DecoratorClass("dec2", public = list(goodbye2 = "Goodbye World 2")) oop <- ooplah$new() oop$goodbye dec_oop <- decorate(oop, c(dec1, dec2)) dec_oop$goodbye dec_oop$goodbye2 ## Equivalently oop <- ooplah$new() decorate(oop, c("dec1", "dec2"))
Creates a decorator R6 class by placing a thin wrapper around R6::R6Class which allows the constructed class to inherit the fields and methods of the given object.
The decorator design pattern allows methods to be added to an object without bloating the interface with too many methods on construction and without causing large inheritance trees. A decorator class contains fields/methods that are 'added' to the given object in construction, this is made clearer in examples.
There are three possibilities when trying to decorate an object with a field/method that already exists:
exists = "skip" (default) - This will decorate the object with all
fields/methods that don't already exist
exists = "error" - This will throw an error and prevent the
object being decorated
exists = "overwrite" - This will decorate the object with all
fields/methods from the decorator and overwrite ones with the same name
if they already exist
Decorators are currently not cloneable.
All arguments of R6::R6Class can be used as usual, see full details at R6::R6Class.
Gamma, E., Helm, R., Johnson, R., & Vlissides, J. (1996). Design Patterns: Elements of Reusable Software. Addison-Wesley Professional Computing Series (p. 395).
library(R6) ## Create two decorators # Works with active bindings... dec1 <- DecoratorClass("dec1", active = list(hi = function() "Hi World")) # And public fields... dec2 <- DecoratorClass("dec2", public = list(goodbye = "Goodbye World")) ## Create an object to decorate oop <- ooplah$new() oop$hello() ## Decorate with dec1 by constructing dec1 with object oop: dec_oop <- dec1$new(oop) # equiv `decorate(oop, dec1)` ## We have all original methods from oop dec_oop$hello() # It's inherited methods dec_oop$init # And now decorated methods dec_oop$hi ## We can decorate again redec_oop <- dec2$new(dec_oop) redec_oop$hello() redec_oop$init redec_oop$hi # And now redec_oop$goodbye # Notice the class reflects all decorators, the original object and parents, # and adds the 'Decorator' class class(redec_oop) ## Decorators also work with inheritance parent_dec <- DecoratorClass("parent_dec", public = list(hi = function() "Hi!")) child_dec <- DecoratorClass("child_dec", inherit = parent_dec) dec_oop <- child_dec$new(ooplah$new()) dec_oop$hi() ## Three possibilities if the method/field name already exists: oop <- ooplah$new() exists_dec <- DecoratorClass("exists_dec", public = list(hello = function() "Hi!")) # 1. skip (default) oop$hello() exists_dec$new(oop, exists = "skip")$hello() # 2. error ## Not run: exists_dec$new(oop) exists_dec$new(oop, exists = "error") ## End(Not run) # 3. overwrite oop$hello() exists_dec$new(oop, exists = "overwrite")$hello() ## Cloning # Note that by default the decorated object is not cloned dec <- DecoratorClass("dec", active = list(hi = function() "Hi World")) dec_oop <- dec$new(oop) dec_oop$logically oop$logically <- FALSE dec_oop$logicallylibrary(R6) ## Create two decorators # Works with active bindings... dec1 <- DecoratorClass("dec1", active = list(hi = function() "Hi World")) # And public fields... dec2 <- DecoratorClass("dec2", public = list(goodbye = "Goodbye World")) ## Create an object to decorate oop <- ooplah$new() oop$hello() ## Decorate with dec1 by constructing dec1 with object oop: dec_oop <- dec1$new(oop) # equiv `decorate(oop, dec1)` ## We have all original methods from oop dec_oop$hello() # It's inherited methods dec_oop$init # And now decorated methods dec_oop$hi ## We can decorate again redec_oop <- dec2$new(dec_oop) redec_oop$hello() redec_oop$init redec_oop$hi # And now redec_oop$goodbye # Notice the class reflects all decorators, the original object and parents, # and adds the 'Decorator' class class(redec_oop) ## Decorators also work with inheritance parent_dec <- DecoratorClass("parent_dec", public = list(hi = function() "Hi!")) child_dec <- DecoratorClass("child_dec", inherit = parent_dec) dec_oop <- child_dec$new(ooplah$new()) dec_oop$hi() ## Three possibilities if the method/field name already exists: oop <- ooplah$new() exists_dec <- DecoratorClass("exists_dec", public = list(hello = function() "Hi!")) # 1. skip (default) oop$hello() exists_dec$new(oop, exists = "skip")$hello() # 2. error ## Not run: exists_dec$new(oop) exists_dec$new(oop, exists = "error") ## End(Not run) # 3. overwrite oop$hello() exists_dec$new(oop, exists = "overwrite")$hello() ## Cloning # Note that by default the decorated object is not cloned dec <- DecoratorClass("dec", active = list(hi = function() "Hi World")) dec_oop <- dec$new(oop) dec_oop$logically oop$logically <- FALSE dec_oop$logically
Assert/test if 'x' is a R6 object or class
is.R6(x) assert_R6(x)is.R6(x) assert_R6(x)
x |
Object to test |
Either TRUE/FALSE is testing if x inherits from
R6 or R6ClassGenerator, otherwise returns x invisibly on assertion
if TRUE or returns an error if FALSE
Assert/test if 'x' is a R6 class
is.R6Class(x) assert_R6Class(x)is.R6Class(x) assert_R6Class(x)
x |
Object to test |
Either TRUE/FALSE is testing if x inherits from
R6ClassGenerator, otherwise returns x invisibly on assertion if TRUE or
returns an error if FALSE
Assert/test if 'x' is a R6 object
is.R6Object(x) assert_R6Object(x)is.R6Object(x) assert_R6Object(x)
x |
Object to test |
Either TRUE/FALSE is testing if x inherits from R6, otherwise
returns x invisibly on assertion if TRUE or returns an error if FALSE
Specialised lapply functions for R6 or other OOP classes.
This is simply a wrapper that detects if FUN is a function, in which
case lapply is used as usual, or a string, in which case the given
field/method is returned as a list.
loapply(X, FUN, ...)loapply(X, FUN, ...)
X, ...
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See lapply |
FUN |
Either a function to apply to each element of |
## lapply as usual loapply(c(1, 2, 3), identity) ## For R6 objects objs <- list(ooplah$new(), ooplah$new()) # Public field loapply(objs, "oop") # Public method loapply(objs, "hello")## lapply as usual loapply(c(1, 2, 3), identity) ## For R6 objects objs <- list(ooplah$new(), ooplah$new()) # Public field loapply(objs, "oop") # Public method loapply(objs, "hello")
Find class of an object or an ancestor of the object. In contrast to class
which returns a class object and all its ancestors, this function returns
either the class of the object itself, or the class of one of its ancestors.
object_class(object, ancestor = 0) get_object_class(object, ancestor = 0, ...) object_classes(..., objects = list(...))object_class(object, ancestor = 0) get_object_class(object, ancestor = 0, ...) object_classes(..., objects = list(...))
object |
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ancestor |
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... |
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objects |
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object_classes is a stripped-down wrapper to get the class of multiple
objects
library(R6) class_a <- R6Class("class_a") class_b <- R6Class("class_b", inherit = class_a) class(class_b$new()) object_class(class_b$new()) object_class(class_b$new(), 1)library(R6) class_a <- R6Class("class_a") class_b <- R6Class("class_b", inherit = class_a) class(class_b$new()) object_class(class_b$new()) object_class(class_b$new(), 1)
Access the private environment of an R6 object
private(x)private(x)
x |
( |
Access the parent environment of an R6 object
super(x)super(x)
x |
( |
Specialised vapply functions for scalars of each of the six atomic classes
in R:
vlapply(X, FUN, ..., USE.NAMES = TRUE) viapply(X, FUN, ..., USE.NAMES = TRUE) vnapply(X, FUN, ..., USE.NAMES = TRUE) vcapply(X, FUN, ..., USE.NAMES = TRUE) vzapply(X, FUN, ..., USE.NAMES = TRUE) vrapply(X, FUN, ..., USE.NAMES = TRUE)vlapply(X, FUN, ..., USE.NAMES = TRUE) viapply(X, FUN, ..., USE.NAMES = TRUE) vnapply(X, FUN, ..., USE.NAMES = TRUE) vcapply(X, FUN, ..., USE.NAMES = TRUE) vzapply(X, FUN, ..., USE.NAMES = TRUE) vrapply(X, FUN, ..., USE.NAMES = TRUE)
X, ..., USE.NAMES
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See vapply |
FUN |
Either a function to apply to each element of |
logical (vlapply)
integer (viapply)
numeric/real (vnapply)
character/string (vcapply)
complex (vzapply)
raw (vrapply)
These are simply wrappers around vapply where FUN.VALUE is pre-filled
with a scalar of the given class.
In addition these can be applied to pull-out fields or methods from R6 or
other OOP objects by supplying the field/method name to FUN. See examples.
## Specialised vapply vlapply(logical(10), identity) vzapply(complex(10), identity) ## For R6 objects objs <- list(ooplah$new(), ooplah$new()) # Public field vcapply(objs, "oop") # Public method vcapply(objs, "exclaim", "ARGH") vcapply(objs, "hello") vnapply(objs, "generate", 1) # Active binding vlapply(objs, "logically")## Specialised vapply vlapply(logical(10), identity) vzapply(complex(10), identity) ## For R6 objects objs <- list(ooplah$new(), ooplah$new()) # Public field vcapply(objs, "oop") # Public method vcapply(objs, "exclaim", "ARGH") vcapply(objs, "hello") vnapply(objs, "generate", 1) # Active binding vlapply(objs, "logically")