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STEM stage v1.0
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Pipelines v2.0
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_NOBUFFER_ _from 1__
>>__STEM__name__|__________|__|_________|______________________________________________><
|_BUFFER___| |_APPEND__|
|_from_n__|
Notes:
(1)
NOBUFFER and BUFFER can only be specified on a STEM stage that does not have a
primary input stream connected.
(2)
APPEND
cannot be specified on a STEM stage that is used as the first stage of a
pipeline.
Use the STEM stage to
retrieve or set an ooRexx compound variable whose name begin with the stem you
specify.
The stem name of an
ooRexx variable is that part of a variable name up to and including
the last period, for example; pipe.var. is the stem of the ooRexx variables pipe.var.1, pipe.var.2,
and pipe.var.3.
When STEM is the first stage of a pipeline, STEM retrieves values of variables.
Before STEM can be used to retrieve variables, variable name.0 must contain the
number of variables whose value you want to retrieve. The value should be 0 or
positive. For each variable retrieved, STEM writes a separate record containing
the variable's value to its primary output stream. By default, output records
are written beginning with name.1,
followed by name.2, name.3 and so on. The output records are
written in ascending order of the numeric suffix of the variables until the
number of records written equals the value of name.0.
When STEM is not the
first stage of a pipeline, STEM sets variables. By default, when STEM is used
to set variables, it sets one variable for each record in its primary input
stream. Variables name.1
through name.n,
where n is the number of
records in the primary input stream, are set to the contents of the first
through the nth input stream
records, respectively. After n
records have been set, STEM sets the variable name.0 to the number of variables that
were set. STEM also copies its primary input stream records to its primary
output stream.
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name
is the name of the
compound variables whose values you want to set or retrieve. The name of an
ooRexx variable is that part of a variable name up to and including the last
period.
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NOBUFFER
specifies that
STEM will make repeated calls into the ooRexx API mechanism to access stem
elements . This is the default.
NOBUFFER can only be specified on
a STEM stage that does not have a primary input stream connected.
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BUFFER
specifies that
STEM will read the entire stem into a buffer before writing any records to
its primary output stream. This option, for small to medium sized stems,
provides the fastest and most efficient option. Repeated calls into the
ooRexx API to request access to stem elements is costly and somewhat slow,
however, a single call where the entire stem is pre-loaded during the STEM
initialisation phase can greatly improve performance.
BUFFER can only be specified on
a STEM stage that does not have a primary input stream connected.
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APPEND
specifies that variables are to be set
beginning with name(n+1) where n is the value of variable name.0.
Variable name.0
must contain a zero or positive whole number prior to invoking the STEM stage
with the APPEND operand. After all variables have been set, STEM sets
variable name.0
to the numeric suffix of the last variable that was set.
APPEND cannot be specified on a STEM stage that is used in the
first stage of a pipeline.
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FROM n
specifies that the
values of variables are to be retrieved or variables are to be set beginning
with name.n where n is the value specified. When retrieving a variable, n should be 0 or positive, and less
than or equal to the value in name.0.
After all variables have been set, when STEM is not the first stage in the
pipeline, STEM sets variable name.0
to the numeric suffix of the last variable that was set. The default value
for n is 1.
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The following streams are used by the STEM stage:
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Stream
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Action
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Primary input stream
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STEM reads records its primary input stream, if it is
connected and writes them the specified ooRexx stem.
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Primary output stream
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STEM writes records to its primary output stream, if it
is connected.
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1)
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STEM does not delay the records.
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2)
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If the STEM stage discovers that both its primary input
and primary output streams are not connected, the STEM stage ends.
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3)
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STEM verifies that it has either
a primary input stream and/or a primary output stream connected and then begins
execution.
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None.
Reference the following links for
additional information:
ARRAY, VARIABLE
None.