Handling French date format in Ruby

gistfile1.rb

## Try 1
# How could I get the following working nicely

Date.strptime("Ven 13 Mai. 2011, 16h00", "%a %d %b %Y, %Hh%M")

# I've tried to update Date::ABBR_DAYNAMES as follow

I18n.locale = :fr
Date::ABBR_DAYNAMES = I18n.t('date.abbr_day_names')
Date::ABBR_MONTHNAMES = I18n.t('date.abbr_month_names')

# So far no luck, it look like Date::ABBR_DAYNAMES, ... are only used for output, not parsing.
# Any trick ?

## Try 2
# Patching Date::Format look like an option. Replacing Date::Format::MONTHS values,
# and so on make it working as expected. However that would work only for French
# so remain unthinkable.
# I've made up a patch that update this constants depending on I18n.locale, ...
# So far all looks good. The constant get updated properly but there's a remaining
# issue that doesn't make any sense to me.
# Here's a quick debug code to showcase the issue, debugging made inside lib/date/format.rb in self._strptime_i

# Pacthed code for debug
puts "str = \"#{str}\"\nstr.sub!(/\\A(#{Format::ABBR_MONTHS.keys.join('|')})/io, '')"
puts str.sub!(/\A(#{Format::ABBR_MONTHS.keys.join('|')})/io, '')

# With default Date::Format

    MONTHS = {
      'january'  => 1, 'february' => 2, 'march'    => 3, 'april'    => 4,
      'may'      => 5, 'june'     => 6, 'july'     => 7, 'august'   => 8,
      'september'=> 9, 'october'  =>10, 'november' =>11, 'december' =>12
    }
    
    DAYS = {
      'sunday'   => 0, 'monday'   => 1, 'tuesday'  => 2, 'wednesday'=> 3,
      'thursday' => 4, 'friday'   => 5, 'saturday' => 6
    }
    
    ABBR_MONTHS = {
      'jan'      => 1, 'feb'      => 2, 'mar'      => 3, 'apr'      => 4,
      'may'      => 5, 'jun'      => 6, 'jul'      => 7, 'aug'      => 8,
      'sep'      => 9, 'oct'      =>10, 'nov'      =>11, 'dec'      =>12
    }
    
    ABBR_DAYS = {
      'sun'      => 0, 'mon'      => 1, 'tue'      => 2, 'wed'      => 3,
      'thu'      => 4, 'fri'      => 5, 'sat'      => 6
    }

str = "Apr 2011, 10:00 am"
str.sub!(/\A(oct|jul|jan|dec|jun|apr|feb|may|sep|aug|mar|nov)/io, '')
# => 2011, 10:00 am
str = "Feb 2011"
str.sub!(/\A(oct|jul|jan|dec|jun|apr|feb|may|sep|aug|mar|nov)/io, '')
# => 2011
str = "Avr. 2011"
str.sub!(/\A(déc.|juil.|sept.|jan.|juin|nov.|oct.|août|fév.|mar.|avr.|mai)/io, '')
# => nil
str = "Avril 2011"
str.sub!(/\A(déc.|juil.|sept.|jan.|juin|nov.|oct.|août|fév.|mar.|avr.|mai)/io, '')
# => nil


# With French Date::Format values HARDCODED (Works)

    MONTHS = {"avril"=>4, "septembre"=>9, "juin"=>6, "mars"=>3, "février"=>2, "janvier"=>1, "novembre"=>11, "août"=>8, "octobre"=>10, "juillet"=>7, "décembre"=>12, "mai"=>5}
    DAYS = {"jeudi"=>3, "samedi"=>5, "dimanche"=>6, "mercredi"=>2, "mardi"=>1, "vendredi"=>4}
    ABBR_MONTHS = {"déc."=>12, "sept."=>9, "juil."=>7, "nov."=>11, "juin"=>6, "jan."=>1, "oct."=>10, "août"=>8, "fév."=>2, "mar."=>3, "mai"=>5, "avr."=>4}
    ABBR_DAYS = {"jeu"=>3, "mer"=>2, "dim"=>6, "mar"=>1, "sam"=>5, "ven"=>4}


str = "Feb 2011"
str.sub!(/\A(déc.|juil.|sept.|jan.|juin|nov.|oct.|août|fév.|mar.|avr.|mai)/io, '')
# => nil
str = "Avr. 2011"
str.sub!(/\A(déc.|juil.|sept.|jan.|juin|nov.|oct.|août|fév.|mar.|avr.|mai)/io, '')
# => 2011
str = "Avril 2011"
str.sub!(/\A(déc.|juil.|sept.|jan.|juin|nov.|oct.|août|fév.|mar.|avr.|mai)/io, '')
# =>  l 2011


# With French Date::Format values PATCHED (Fails)

str = "Apr 2011, 10:00 am"
str.sub!(/\A(oct|jul|jan|dec|jun|apr|feb|may|sep|aug|mar|nov)/io, '')
# => 2011, 10:00 am
str = "Feb 2011"
str.sub!(/\A(oct|jul|jan|dec|jun|apr|feb|may|sep|aug|mar|nov)/io, '')
# => 2011
str = "Avr. 2011"
str.sub!(/\A(déc.|juil.|sept.|jan.|juin|nov.|oct.|août|fév.|mar.|avr.|mai)/io, '')
# => nil
str = "Avril 2011"
str.sub!(/\A(déc.|juil.|sept.|jan.|juin|nov.|oct.|août|fév.|mar.|avr.|mai)/io, '')
# => nil


### Why is that? What could potentially go wrong ???
### Patch attempt available at https://github.com/ZenCocoon/I18n-date-parser