String interpolation (eg fmt) raises undeclared identifier but identifier is in scope

[joshgoebel]

I have a macro generating code:

  result.add quote do:
    proc find*(t: type[`model`], id: string | int) : `model` =
      echo tableName # no error here
      ...
      var query = sql(&"select * from {tableName} where {pk}  = ?") # Error: undeclared identifier: 'tableName'

    proc insert*(p: var `model`) : int64 =
      echo "TABLENAME ",&"{tableName}" # no error here
      var query = sql(&"insert into {tableName} {full_insert} values {full_values}") # no error here

tableName is a const at the top-level that has been generated elsewhere.

What happens

What happens is the interpolation in find fails with Error: undeclared identifier: 'tableName'. The interpolation in insert works just fine.

What I expect to happen

What I expect to happen is that the value of tableName is inserted into the string for find (just as it is successfully is for insert.

Possible Solution

If you first assign the constant to anther local variable (jumping thru all the ident quoting hoops) and then try to interpolate it it will work.

IE:

  var tn = ident"tn"
  var idtableName = ident"tableName"
  result.add quote do:
    proc find*(t: type[`model`], id: string | int) : `model` =
      var `tn` = `idtableName`
      var query = sql(&&"select * from {tn} where {pk}  = ?") # Error: undeclared identifier: 'tableName'

This makes working with interpolation in macros crazy cumbersome though. I'm hoping I'm mising something.

Additional Information

I found and tried -d:debugFmtDsl but it didn't reveal anything I thought would be useful.

[krux02]

Can you extend the source code so that I can reproduce the error?

EDIT:

I just read your example again. String interpolation doesn't work in macro/template context. This is a known problem. Use string concatenation or the format proc instead, sorry for the inconvenience.

[bluenote10]

When closing as a duplicate it would be good to link to it: #7632