CallbackResult-class: Asynchronous callback functions
In omegahat/Aspell: Interface to aspell library
Description
Objects from the Class
Slots
Extends
Methods
Note
Author(s)
References
See Also
Description
These classes provide a way to provide structure
to the concept of a function that is used as
an asynchronous callback or handler.
The idea is that one associates a callback function
with something that generates events.
When an event occurs, the callback function is
invoked.
We use this in the Aspell package for checking the spelling
of words in a document. We pass the callback function
to spellDoc. It iterates over the content
of the document and when it encounters an mis-spelled word,
it invokes the callback function, providing it with
the mis-spelled word, its location, the entire text of the document
and the speller object responsible for performing the spell-checking.
The CallbackResult class is an extension of the basic notion
of a Callback function. This is used to provide a way to
retrieve the “answer” when the entire processing is done.
In this version, the CallbackResult provides information
about which variable in the environment of the callback
function contains the result. This allows the iterating function
to return the result at the end rather than requiring the caller
to access it separately.
We imagine that one would create derived/extended classes
from these that validate the formal arguments of the
specified function to match the event type.
Also, one might provide methods for getResult
to obtain the result from a Callback in different
ways than using a named variable. For instance, it
may involve dynamic computations.
Objects from the Class
Objects can be created by calls of the form new("CallbackResult", ...).
Slots
.Data:Object of class "function". This is the
callback function that is to be invoked when an event occurs.
variable:Object of class "character". The name
of the variable within the
Extends
Class "Callback", directly.
Class "function", by class "Callback".
Class "OptionalFunction", by class "Callback".
Class "PossibleMethod", by class "Callback".
Methods
- spellDoc
signature(doc = "ANY", wordHandler = "CallbackResult"):
check the spelling of the contents of a document and return the
results as gathered by the wordHandler object.
Note
These classes are not specific to Aspell, but are here
for the moment as there is no other good place to house
them. The concept does arise in many places (e.g. GUIs,
XML parsing) and we will want to move the code to a general
package.
Author(s)
Duncan Temple Lang <duncan@wald.ucdavis.edu>
References
See Also
omegahat/Aspell documentation built on May 24, 2019, 1:50 p.m.
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Description Objects from the Class Slots Extends Methods Note Author(s) References See Also
Description
These classes provide a way to provide structure
to the concept of a function that is used as
an asynchronous callback or handler.
The idea is that one associates a callback function
with something that generates events.
When an event occurs, the callback function is
invoked.
We use this in the Aspell package for checking the spelling
of words in a document. We pass the callback function
to spellDoc. It iterates over the content
of the document and when it encounters an mis-spelled word,
it invokes the callback function, providing it with
the mis-spelled word, its location, the entire text of the document
and the speller object responsible for performing the spell-checking.
The CallbackResult class is an extension of the basic notion
of a Callback function. This is used to provide a way to
retrieve the “answer” when the entire processing is done.
In this version, the CallbackResult provides information
about which variable in the environment of the callback
function contains the result. This allows the iterating function
to return the result at the end rather than requiring the caller
to access it separately.
We imagine that one would create derived/extended classes
from these that validate the formal arguments of the
specified function to match the event type.
Also, one might provide methods for getResult
to obtain the result from a Callback in different
ways than using a named variable. For instance, it
may involve dynamic computations.
Objects from the Class
Objects can be created by calls of the form new("CallbackResult", ...).
Slots
.Data:Object of class
"function". This is the callback function that is to be invoked when an event occurs.variable:Object of class
"character". The name of the variable within the
Extends
Class "Callback", directly.
Class "function", by class "Callback".
Class "OptionalFunction", by class "Callback".
Class "PossibleMethod", by class "Callback".
Methods
- spellDoc
signature(doc = "ANY", wordHandler = "CallbackResult"): check the spelling of the contents of a document and return the results as gathered by thewordHandlerobject.
Note
These classes are not specific to Aspell, but are here for the moment as there is no other good place to house them. The concept does arise in many places (e.g. GUIs, XML parsing) and we will want to move the code to a general package.
Author(s)
Duncan Temple Lang <duncan@wald.ucdavis.edu>
References
See Also
R Package Documentation
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Note that we can't provide technical support on individual packages. You should contact the package authors for that.
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