Template Substitutions - ISISComputingGroup/ibex_developers_manual GitHub Wiki

Wiki > The Backend System > IOCs > Template Substitution

Template substitution allows you to take a database template file and substitute the macros in it for a list of chosen values, the documentation for this can be found here. This is used for example to create the same set of records for North, East, South, and West jaw blades. This helps to avoid writing a lot of duplicate PVs.

This requires two files: a .template and a .substitutions file

• The .substitutions file loads the .template (or several) and runs a list of macro substitutions on it. This lives inside the IOC under \<iocDir>\<ioc>App\Db\<something>.substitutions.
• The .template file looks the same as a .db. It can live anywhere, you just need to specify the right path in the .substitutions file.

To build a .db from this, you need to include a reference to the .substitutions file in the makefile in the same folder, e.g.: DB += <something>.db (this instruction will look, in order, for a .db, then a .template, then a .substitutions file named <something>)

The general format of a substitutions file is as follows:

file <FILEPATH_1> { 
  pattern 
    {MACRO_1, MACRO_2, (...) MACRO_N}
    
    {"MACRO_1_SUB_1", "MACRO_2_SUB_1", (...) "MACRO_N_SUB_1"}
    {"MACRO_1_SUB_2", "MACRO_2_SUB_2", (...) "MACRO_N_SUB_2"}
    (...)
    {"MACRO_1_SUB_M", "MACRO_2_SUB_M", (...) "MACRO_N_SUB_M"}
}

file <FILEPATH_2> { 
    ...
}

This will create M sets of records, with each of the N macros replaced with what is specified in each row. Note that you need to substitute every macro that occurs in the .template file, otherwise the substitution procedure will fail. If it's something you don't want to replace (e.g. the PV Prefix) you can just replace it with itself.

See IOC Utilities for some practical examples.