util.py 文件源码

def subst_vars (s, local_vars):
    """Perform shell/Perl-style variable substitution on 'string'.  Every
    occurrence of '$' followed by a name is considered a variable, and
    variable is substituted by the value found in the 'local_vars'
    dictionary, or in 'os.environ' if it's not in 'local_vars'.
    'os.environ' is first checked/augmented to guarantee that it contains
    certain values: see 'check_environ()'.  Raise ValueError for any
    variables not found in either 'local_vars' or 'os.environ'.
    """
    check_environ()
    def _subst (match, local_vars=local_vars):
        var_name = match.group(1)
        if var_name in local_vars:
            return str(local_vars[var_name])
        else:
            return os.environ[var_name]

    try:
        return re.sub(r'\$([a-zA-Z_][a-zA-Z_0-9]*)', _subst, s)
    except KeyError, var:
        raise ValueError, "invalid variable '$%s'" % var

# subst_vars ()