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Module history_collector
Module history_collector consists of a single
class, HistoryCollector. An instance of HistoryCollector contains
an ordered list of instances of class Tag.
A tag is a group of items that should be sampled at the same
times and those samples written out to a history medium, such as
a text file. Each tag has a name, a medium, and a list of items
to be sampled. Tags have names so that they may be registered
with their collector by name. Then, even if you do not have a
reference to the tag, you can get one from the collector. Also,
you can use the tag names to change the order in which different
tags are processed, or to delete the tag from the collector.
Creation
HistoryCollector ()
An instance of HistoryCollector is returned, with an
empty taglist.
Attributes
taglist is the list of tags owned by
this collector.
Query Methods
tag (name) returns the tag
named name, or raises NameError if there isn't one.
position (name) the position
in taglist of the tag named name, or
raises NameError if the name is not the name of a tag in taglist..
tagnames () returns a list of the
names of the tags in taglist.
Manipulating the tag list
The list taglist can be manipulated with these commands.
add (tag, position
= -1) adds the given tag to the
list at the given position. By default, the position is
the end of the list.
delete (name) removes the
tag named name from the taglist.If
there is no such tag, NameError is raised.
at_cycles (*cycles)
similarly takes one or more specific cycles at which to
sample.
Methods to Sample
These routines are used to collect samples of the tags
currently in taglist. For each tag in the
list:
sample (cycle, time)
checks the state attribute of the logical
condition. If it is true, and the state
attribute of the regular condition is satisfied, the
sample is collected. The user's sequence of calls to
sample should have successive integer values of cycle and
monotonically increasing values of time. The initial
value of cycle may be anything you like as long as it is
larger than history.NeverCollected.
If your program has a repetitive cycle but no concept
of time, you can simply use the floating-point version of
the cycle number as a time.
sample_final (cycle, time)
may be called at the final time of the program. It will
example the state_final attributes of its
conditions rather than the normal state
attribute. (See module history_condition). These
state_final attributes have been chosen for the time and
cycle conditions so that they are true unless the last
possible time has already passed.
sample_unconditionally (cycle,
time) does exactly what it says. The logical and
regular conditions are ignored. It is not intended for
normal use by the user.
The method sample_final may be called without
worry about duplication of records that may have already been
made by a previous call to sample on that same
cycle.
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