PyHelper

Extra Python Interop for invocation, arguments and return types

Install:

IPM (ZPM): install alwo-pyhelper

TupleOut feature

When accessing IRIS methods from Python there are some useful output parameters that are convenient to also access in addition to a return type. Consider the following example where we retrieve the text value found at a location in an HL7 message:

> import iris
> hl7=iris.cls("EnsLib.HL7.Message")._OpenId(145,0)
> hl7.GetValueAt("MSH:9.1")
'OUL'

As a non-empty value was retuned we can be reasonably confident that the function succeeded as intended. But what happens if we try an invalid path?

> hl7.GetValueAt("<&$BadMSH:9.1")
''

An empty value was returned. However is this empty string valid, OR did something go wrong? The class in our example, EnsLib.HL7.Message, provides a supporting OUTPUT parameter "pStatus" that will inform on the validity of value being returned. Using the TupleOut feature we can access both the return value and this method success status in one operation.

> hl7=iris.cls("EnsLib.HL7.Message")._OpenId(145,0)
> val, status = iris.cls("alwo.PyHelper").TupleOut(hl7,"GetValueAt",['pStatus'],1,"<&$BadMSH:9.1")
> val==''
True
> iris.cls("%SYSTEM.Status").IsError(status)
1
> iris.cls("%SYSTEM.Status").DisplayError(status)
ERROR <Ens>ErrGeneral: No segment found at path '<&$BadMSH'1

Returning ByRef literal as though Output

Historically, from objectscript parameters would be passed By-Reference for "dictionaries" for both input and output. The Output directive evolved later and so there is much implementation using ByRef when the API intention was intented for what is now just Output. Therefore it is useful to be able to access internal ByRef literals as though they has been implemented as accessible Output parameters. Simply include the ByRef parameter name and it will be included in the output Tuple

> out,tsc=iris.cls("alwo.PyHelper").TupleOut("EnsLib.HL7.Message","%OpenId",['sc'],1,'er145999', 0)
> out
''
> iris.cls("%SYSTEM.Status").DisplayError(tsc)
ERROR #5809: Object to Load not found, class 'EnsLib.HL7.Message', ID 'er145999'1

Support for %objlasterror

In objectscript there is access to percent variables across method scope. There are scenarios where detecting or accessing special variable %objlasterror is useful after calling a CORE or thirdparty API. This utility facilitate Python context access to the %objlasterror variable as though it has been defined as an Output parameter, when invoking methods from Python.

> del _objlasterror
> out,_objlasterror=iris.cls("alwo.PyHelper").TupleOut("EnsLib.HL7.Message","%OpenId",['%objlasterror'],1,'er145999', 0)
> iris.cls("%SYSTEM.Status").DisplayError(_objlasterror)
ERROR #5809: Object to Load not found, class 'EnsLib.HL7.Message', ID 'er145999'1

Arguments explained

IRIS List and Array to / from Python List and Dictionary

Supporting functions

ArrayFrompyDict

ListFrompyList

toPyListOrString

pyDictFromArray