how to return the name of a variable?

SKILL doesn't work that way. Variables are just a way of associating a symbol with a value (usually a pointer). Multiple variables can point to the same object, and you can't go from the object itself to the variable name (so for example, the same data is pointed to by top-level variable abc and formal parameter myGeoLayer).

There are two ways of achieving what you want, although these may not necessarily be a good idea depending on what you're doing. First is to pass the name of the variable to the function rather than the actual object - so for example:

procedure(geoStuff(geoVarName)
  let(((myGeoLayer symeval(geoVarName))) ; if this code is in SKILL++ mode, pass theEnvironment() as second arg to symeval
    printf("name of the geo layer: %L with value: %L\n" geoVarName myGeoLayer)
  )
)

Then you'd call: geoStuff('abc) . The downside of this approach is that it needs a small amount of run-time evaluation (not terribly expensive, since it's just looking up a symbol), plus a bit of code inconvenience because you have to pass the quoted variable name to the function.

An alternative is to use macro instead. Macros are evaluated at compile-time and return the expanded code. For example:

defmacro(geoStuff (geoExpr)
  `let(() ; add your local vars here
     printf("name of the geo layer: %L with value: %L\n" ',geoExpr ,geoExpr)
  )
)

The downside of using a macro is that it gets a bit more complicated writing it, because in essence you need to stuff in the arguments into the right place in the code, plus there's the general downside that it's very easy to end up with a complex macro that is hard for a reader of the code to understand (both the macro definition and use of the macro, because it is effectively extending the language). For example, you need to be careful about using the same argument more than once because it can end up evaluating that argument more than once (depending on how you use it). It also isn't strictly speaking showing the name of the variable - for example, if you did:

geoStuff(abeNewLayer())

then it would output:

name of the geo layer: abeNewLayer() with value: geoLayer:44814020

Anyway, at least that has given you some potential options.

Andrew

SKILL doesn't work that way. Variables are just a way of associating a symbol with a value (usually a pointer). Multiple variables can point to the same object, and you can't go from the object itself to the variable name (so for example, the same data is pointed to by top-level variable abc and formal parameter myGeoLayer).

There are two ways of achieving what you want, although these may not necessarily be a good idea depending on what you're doing. First is to pass the name of the variable to the function rather than the actual object - so for example:

procedure(geoStuff(geoVarName)
  let(((myGeoLayer symeval(geoVarName))) ; if this code is in SKILL++ mode, pass theEnvironment() as second arg to symeval
    printf("name of the geo layer: %L with value: %L\n" geoVarName myGeoLayer)
  )
)

Then you'd call: geoStuff('abc) . The downside of this approach is that it needs a small amount of run-time evaluation (not terribly expensive, since it's just looking up a symbol), plus a bit of code inconvenience because you have to pass the quoted variable name to the function.

An alternative is to use macro instead. Macros are evaluated at compile-time and return the expanded code. For example:

defmacro(geoStuff (geoExpr)
  `let(() ; add your local vars here
     printf("name of the geo layer: %L with value: %L\n" ',geoExpr ,geoExpr)
  )
)

The downside of using a macro is that it gets a bit more complicated writing it, because in essence you need to stuff in the arguments into the right place in the code, plus there's the general downside that it's very easy to end up with a complex macro that is hard for a reader of the code to understand (both the macro definition and use of the macro, because it is effectively extending the language). For example, you need to be careful about using the same argument more than once because it can end up evaluating that argument more than once (depending on how you use it). It also isn't strictly speaking showing the name of the variable - for example, if you did:

geoStuff(abeNewLayer())

then it would output:

name of the geo layer: abeNewLayer() with value: geoLayer:44814020

Anyway, at least that has given you some potential options.

Andrew

Makes sense - thanks for the quick helpful detail and pros-and-cons analysis as always!