Re: [PATCH] oe.types: give the regex type more sane semantics

[Saul Wold <sgw@linux.intel.com>]

On 05/16/2012 04:26 AM, Christopher Larson wrote:
> From: Christopher Larson<chris_larson@mentor.com>
>
> Currently, if a variable is unset or has an empty value, the regex type
> will return a match object which always matches. Not all variable types
> will necessarily have the same behavior for handling defaults. I believe
> that returning a match object which matches nothing when a variable is
> unset is superior to returning one which matches anything, and the user
> can always explicitly request anything via '.*', if that's what they
> want.
>
> This constructs a null pattern object which will never match, and uses
> it when encountering an unset or empty variable (currently, these two
> things are one and the same, as maketype is handling the default. we may
> well want to shift that logic into the individual types, giving them
> more control over default behavior, but currently the behavior is at
> least relatively consistent -- no difference between unset and empty
> variables).
>
> Signed-off-by: Christopher Larson<chris_larson@mentor.com>
> ---
>   meta/lib/oe/types.py |   31 +++++++++++++++++++++++++++++++
>   1 files changed, 31 insertions(+), 0 deletions(-)
>
> diff --git a/meta/lib/oe/types.py b/meta/lib/oe/types.py
> index ea31cf4..ea53df9 100644
> --- a/meta/lib/oe/types.py
> +++ b/meta/lib/oe/types.py
> @@ -40,6 +40,31 @@ def choice(value, choices):
>                            (value, choices))
>       return value
>
> +class NoMatch(object):
> +    """Stub python regex pattern object which never matches anything"""
> +    def findall(self, string, flags=0):
> +        return None
> +
> +    def finditer(self, string, flags=0):
> +        return None
> +
> +    def match(self, flags=0):
> +        return None
> +
> +    def search(self, string, flags=0):
> +        return None
> +
> +    def split(self, string, maxsplit=0):
> +        return None
> +
> +    def sub(pattern, repl, string, count=0):
> +        return None
> +
> +    def subn(pattern, repl, string, count=0):
> +        return None
> +
> +NoMatch = NoMatch()
> +
>   def regex(value, regexflags=None):
>       """OpenEmbedded 'regex' type
>
> @@ -59,6 +84,12 @@ def regex(value, regexflags=None):
>               except AttributeError:
>                   raise ValueError("Invalid regex flag '%s'" % flag)
>
> +    if not value:
> +        # Let's ensure that the default behavior for an undefined or empty
> +        # variable is to match nothing. If the user explicitly wants to match
> +        # anything, they can match '.*' instead.
> +        return NoMatch
> +
>       try:
>           return re.compile(value, flagval)
>       except re.error, exc:

Merged this series of 3 patches into OE-Core

Thanks
	Sau!