Recursive Variable Evaluation

jharbison

Is there a way to have variable expansion inside of another variable? It would be nice to be able to build up variables using other variables that are fully evaluated during execution.

{
  "CommonPath": "\common\path",
  "SpecificPath1": "$CommonPath\specific\place\here",
  "SpecificPath2": "$CommonPath\another\place\there"
}

Log-Information $SpecificPath2;

INFO:  \common\path\another\place\there

Product: BuildMaster
Version: 5.6.8

You can do this with the $Eval function:

set $CommonPath = "\common\path";

set $SpecificPath2 = "`$CommonPath\another\place\there";

Log-Information $Eval($SpecificPath2);

Note the escaped variable in $SpecificPath2 that prevents the initial expansion.

Does that help?

Yes, thank you. This will work for my purposes although it is less than ideal having to litter $Eval statements throughout my plans. Also, when using properties set outside of a plan (e.g. application variables) this requires putting $Eval in the property definition

{
  "CommonPath": "\common\path",
  "SpecificPath1": "$CommonPath\specific\place\here",
  "SpecificPath2": "$Eval($CommonPath)\another\place\there"
}
Log-Information $SpecificPath1;
Log-Information $SpecificPath2;

INFO: $CommonPath\specific\place\here
INFO:  \common\path\another\place\there

It would be nice to be able to always fully expand variables. I realize changes around variable expansion could cause regression issues for clients but perhaps having the ability to set a parameter that modifies how evaluation is handled in the current context would be manageable.

set $VariableExpansion = Full;

We will implement this eventually once we have the specs nailed down. The plan is to offer a per-variable setting (in the same vein as the "sensitive" option) so it shouldn't break backwards compatibility.