Table of Contents

Class: EigenCell ./src/peak/util/EigenData.py

Hold a value which can be changed as long as it has not been examined

An EigenCell is used to hold a configuration value that should not be changed once it is used. The value may be set() or unset() at will as long as the exists() or get() methods have not been called. As soon as the cell's value has been read or tested for existence, the value is locked and an AlreadyRead exception will be thrown if you attempt to set() or unset() the value after that point. (Note: unset() is a no-op if the value is empty, whether the cell is locked or not, because it does not change the value's nonexistence.)

Base Classes   
object
Methods   
__init__
exists
get
set
unset
  __init__ 
__init__ ( self )

Create an (empty and unread) EigenCell

  exists 
exists ( self )

Return true if the cell contains a value.

  get 
get ( self,  setdefault=None )

Return the cell's value, or raise AttributeError if empty

A function may be supplied to set a default value, if the cell has not yet been read and no value is currently assigned. The return value of the function will be used. For example:

            aCell.get(lambda: someObj())

will set the value of aCell to someObj() if aCell has not been read and has no value currently assigned. Notice that you must pass a function, not a value. The simplest way to do this is with lambda as shown above.

  set 
set ( self,  value )

Set the cell's value, or raise AlreadyRead

Exceptions   
AlreadyRead
  unset 
unset ( self )

Remove the cell's value (reset to non-existence)

Exceptions   
AlreadyRead

Table of Contents

This document was automatically generated on Mon May 20 01:11:19 2019 by HappyDoc version 2.1