The goal of gendatypes is to provide generic data structures and utilities for restricting usage of lists to only one specific generic class. Among the utilities: extend list of classes only if the list doen’t contain provided class name or introduce S3 %??% which by default works similar to null coalescing operator in C#, however it can be overriden.
Installation
Currently the package is not deployed to CRAN. For installation use install_github command from devtools package.
devtools::install_github("valercheck/gendatypes")To install specific version use ref option and provide branch or tag name. Release tags use 4 numbers in version with v prefix.
devtools::install_github("valercheck/gendatypes", ref = "v0.0.0.2")Functions
Current version contains next functions:
| Function name | Parameters | Description |
|---|---|---|
| with_class |
obj: input object className: class name to apply |
Extend object with provided class name. Will apply class only if object doesn’t alreay contain provided class |
| validate_classes |
object: object to validate …: dots used as replacement for classes parameter. Will be used if classes won’t be provided. classes: collection of classes which object must have |
If provided object contains required classes, nothing will happen and function will be silently executed. Otherwise, execution will stop with error message. |
| c_extended |
…: items to be used for vector creation as.names: make names of the vector to be equal to values. as.list: generate list object instead of vector. as.names in this case will change names in vector to keys in a list. |
This is just extension for vector creation to reduce code for making names of vector equal to values. Useful when there are string values, which should be available by the same keys in this vector. |
| %??% |
lhs: left operand rhs: right operand |
Inspired by C# null-coaelsing operator ?? which allows working with null values. In case if left hand side object is NaN, NULL, NA, or empty vector then right hand side object will be used. Otherwise left hand side object will be used. |
| throw_exception |
arg: argument which will be mentioned in error message: additional message to show before stopping execution. |
Inspired by ArgumentException in C# |
| as.typed_list |
x: object to convert to typed list. Typically it should be a list of items type_class: class which all items in provided collection must have |
When you have list(object1, object2, object3) and you want to make your list at least partially strongly typed by checking whether all items in the list have the same class definition |
| is_typed_list | x: input object | Check whether provided object is typed list |
| typed_list.typeof | x: input object | Returns generic item type in typed list |
| typed_list.is |
x: input object type_class: type class to verify |
Returns either TRUE or FALSE based on comparison of generic item type with provided type_class
|
| validate_typed_list_class | x: input object | Same as is_typed_list except it will stop execution with error if outcome of is_typed_list is FALSE
|
$.typed_list |
x: input object name: property name |
S3 method for $ function for typed_list. Returns a collection of properties by property name from each typed_list item |
%$% |
lhs: input object. Must have class typed_list. rhs: property name on which perform expansion |
Operator which works like $.typed_list except the result from this operator will give also typed list but not a vector of items or matrix |