Get module variable by String

Question

Hi,

I have a String Parameter with index domain “i” called “ModPrefix” containing prefixes of modules within my project. Each of this modules has a variable with the name “Q”. Now, I would like to access these variables within the definition of a Node called “FacilityNode” like

NetOutflow = ModPrefix(i)::Q

However, this leads to the error

The identifier "Q" has not been declared, but it is declared in the modules [...].

where I replaced the names of the modules with “[...]”.

My idea of a workaround was an if-then-else-statement like

NetOutflow = 
    if ( ModPrefix(i) = "prefix1" ) then
        prefix1:Q
    elseif ( ModPrefix(i) = "prefix2" ) then
        prefix2:Q
    else
        0
    endif;

in the case of two modules with prefixes “prefix1” and “prefix2”. However, I would still like to know if there is a way to circumvent it-then-else-statements, since they become ugly in the case of many modules.

Chris Kuip · Accepted Answer

Hi Sebastian,You will need to create runtime identifiers, and the identifiers should be of type constraint.Please check out:Language to create runtime identifiers - https://documentation.aimms.com/language-reference/advanced-language-components/model-structure-and-modules/runtime-libraries-and-the-model-edit-functions.htmlProcedure and functions that you can use - https://documentation.aimms.com/functionreference/model-handling/model-edit-functions/index.htmlAn example that creates runtime identifiers of type constraint - https://how-to.aimms.com/Articles/131/131-Formulas-as-Data.htmlWith kind regards,Chris

Chris Kuip · Answer

Hi,Hope this helps:NetOutFlow =    ScalarValue(        StringToElement(             AllIdentifiers,            formatString("%s::Q", ModPrefix(i) ) ) )

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