Keyword

class Cauldron.base.dispatcher.Keyword

Bases: Cauldron.base.core._BaseKeyword

A dispatcher-based keyword, which should own its own values.

Attributes Summary

value

Map .value to ._last_value, the cauldron internal location of this variable.

Methods Summary

callback(function[, remove])	Register a function to be called whenever this keyword is set to a new value.
check(value)	Check that ‘value’ is appropriate for this keyword.
modify(value)	Modify this keyword’s value.
period(period)	How often a keyword should be updated.
postread(value)	Take some action post-read.
postwrite(value)	Take some action post-write.
preread()	Take some action before this value is read.
prewrite(value)	Any actions which need to occur before a value is written.
read()	Read the value from the authority source.
schedule([appointment, cancel])	Schedule an update.
set(value[, force])	Set the keyword to the value provided, and broadcast changes.
translate(value)	Translate a value into a standard representation.
update()	Update the value by performing a read.
write(value)	Write the value to the authority source.

Attributes Documentation

value

Map .value to ._last_value, the cauldron internal location of this variable.

Methods Documentation

callback(function, remove=False)

Register a function to be called whenever this keyword is set to a new value.

check(value)

Check that ‘value’ is appropriate for this keyword. If it is not, raise a value error.

This method can be overridden to provide specific behavior in user subclasses.

modify(value)

Modify this keyword’s value. This is the public function which should be called to change a keyword value.

period(period)

How often a keyword should be updated.

Warning

period is not implemented in the Cauldron version of the KTL API.

postread(value)

Take some action post-read. Called at the end of update().

This method can be overridden to provide specific behavior in user subclasses.

postwrite(value)

Take some action post-write.

This method can be overridden to provide specific behavior in user subclasses.

preread()

Take some action before this value is read. Called at the start of update().

This method can be overridden to provide specific behavior in user subclasses.

prewrite(value)

Any actions which need to occur before a value is written. Called to adjust the value in modify().

This can raise NoWriteNecessary if a write is not necessary.

This method can be overridden to provide specific behavior in user subclasses.

read()

Read the value from the authority source. Called to get the value for update().

This method can be overridden to provide specific behavior in user subclasses.

schedule(appointment=None, cancel=False)

Schedule an update.

Warning

schedule is not implemented in the Cauldron version of the KTL API.

set(value, force=False)

Set the keyword to the value provided, and broadcast changes.

Parameters:

• value – The keyword value.
• force (bool) – Whether to force the change, or ignore repeatedly setting a keyword to the same value.

translate(value)

Translate a value into a standard representation.

This method can be overridden to provide specific behavior in user subclasses.

update()

Update the value by performing a read. This is the public function which should be called when the keyword is read.

write(value)

Write the value to the authority source. Called to adjust the value in modify().

This method can be overridden to provide specific behavior in user subclasses.