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3685 :: Need help with macro

• shashlick (orginal) [2018-03-26T06:54:12+02:00] view original

  I'm having some trouble with a macro setupDepFile() I'm working on. I'm trying to call it from a proc setupDepFilesProc() but getting a compilation error. I want to use a proc since I want to do some additional work before calling the macro. However, it doesn't like the parameter types I pass to setupDepFile().

  
  Error: type mismatch: got <string, bool>
  but expected one of:
  macro setupDepFile(filename: static[string]; autowrite: static[bool]): untyped
    first type mismatch at position: 1
    required type: static[string]
    but expression 'filename' is of type: string
  Run

  Also a secondary issue where I'm not getting the correct return value on fileExists() in setupDepFiles().

  Code below:-

  import macros
  import os
  import strutils
  
  proc writeDepFile*(constname, filename: string) =
      let pdir = parentDir(filename)
      if not dirExists(pdir):
          try:
              createDir(pdir)
          except OSError:
              echo "Failed to create directory: " & pdir
              quit()
      
      if not existsFile(filename) or getFileSize(filename) != constname.len:
          writeFile(filename, constname)
      
      while not existsFile(filename):
          sleep(10)
  
  macro setupDepFile*(filename: static[string], autowrite: static[bool]): untyped =
      result = newNimNode(nnkStmtList)
      echo staticRead(filename)
      if not fileExists(filename):                # <========== this always returns failed even if file exists and is read in line 22
          echo "Could not find " & filename
          quit()
      
      var
          vname = filename.multiReplace([
              ("/", "_"), ("\\", "_"), (":", "_"), (".", "_")
          ]).toUpperAscii()
          ivname = ident(vname)
      
      if vname[0] == '_': vname = "V" & vname
      
      result.add(quote do:
          const `ivname` = staticRead `filename`
      )
      
      if autowrite:
          result.add(quote do:
              writeDepFile(`ivname`, `filename`)
          )
  
  macro setupDepFiles*(filenames: static[seq[string]], autowrite: bool): untyped =
      result = newNimNode(nnkStmtList)
      for filename in filenames:
          result.add(quote do:
              setupDepFile(`filename`, `autowrite`)
          )
  
  proc setupDepFilesProc*(filenames: seq[string], autowrite: bool) =
      for filename in filenames:
          setupDepFile(filename, autowrite)               # <========== compilation error as below
  
  setupDepFiles(@["data.txt"], true)
  setupDepFilesProc(@["data.txt"], true)
  Run

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• Varriount (orginal) [2018-03-26T09:56:12+02:00] view original

  Your setupDepFile macro can only take static parameters - the parameter values must be known at compile-time. On line 53, your are passing a string and boolean that have may have values unknown at compile-time values. Yes, the function calls on lines 54 and 55 have known values, but the compiler doesn't look that far for static inferencing.

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• shashlick (orginal) [2018-03-26T15:10:12+02:00] view original

  If I use untyped params instead, is it possible? Further, how do you get to value of the param if untyped? If I use strVal(), it says strVal() not found.

  Also am still wondering why fileExists() always fails.

  Thank you.

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• shashlick (orginal) [2018-03-26T15:33:00+02:00] view original

  I figured out the fileExists() issue - staticRead() looks for files in the directory relative to the source file it is contained in whereas fileExists() runs relative to the working directory.

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