subst.py.in

import re

# Replacement utilities
_configvar_re = re.compile(r"[@][a-zA-Z_]*[@]")

def configvar_replace(config, text):
    """"Substitute configuration variables with form @NAME@ with their
    values."""

    def replacer(match_object):
        try:
            cv = match_object.group(0)[1:-1]
        except:
            raise ValueError("Error when substituting the configuration "
                             "variable.")
        if len(cv) == 0:
            return "@"

        else:
            val = config.get(cv, None)
            return str(val) if val != None else ""

    return re.sub(_configvar_re, replacer, text)

def configvar_replace_file(config, filename_in, filename_out=None):
    """Copy file with name filename_in to a file with name filename_out,
    replacing all configuration variables with form "@NAME@" with their values.
    """
    if filename_out == None:
        filename_out = os.path.splitext(filename_in)[0]

    with open(filename_in, "r") as f:
        text_in = f.read()

    text_out = configvar_replace(config, text_in)

    with open(filename_out, "w") as f:
        f.write(text_out)

configuration = @CONFIGURATION@

import sys
filename_in = sys.argv[1]
filename_out = (sys.argv[2] if len(sys.argv) > 1 else None)

configvar_replace_file(configuration, filename_in, filename_out)