How to echo/print at compile time in Nim?

Question

When working on compile time features it would be nice to echo something at compile time. If an echo is withing a macro it is already executed at compile time. But is it also possible to print something at compile time e.g. from the global scope? I'm looking for a function like echoStatic in this:

echoStatic "Compiling 1. set of macros..."

# some macro definitions

echoStatic "Compiling 2. set of macros..."

# more macro definitions

Just a self-documenting question, because I keep forgetting the solution... — bluenote10, Feb 19 '17 at 12:28

score 9 · Accepted Answer · edited May 23 '17 at 11:53

9

There is no need for a special echoStatic. This is solved by the general solution of running code at compile time, which is to use a static block:

static:
  echo "Compiling 1. set of macros..."

# some macro definitions

static:
  echo "Compiling 2. set of macros..."

# more macro definitions

edited May 23 '17 at 11:53

Community

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answered Feb 19 '17 at 12:28

bluenote10

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score 1 · Answer 2 · answered Nov 28 '21 at 19:32

In languages like C, C++ and D, you can typically use a pragma for this job. This also works for Nim:

from strformat import `&`

const x = 3
{. hint: &"{$typeof(x)} x = {x}" .}  # <file location> Hint: int x = 3

It also prints the file, the line and the column which can be useful for compile-time debugging.

How to echo/print at compile time in Nim?

2 Answers2