[wiki:DeveloperGuidelines] | S3

= S3 Framework Extensions for Web2py =

All S3 framework extensions for web2py reside as a Python package in {{{modules/s3}}}:

||'''Module'''||'''Functionality'''||
||s3aaa||Authentication, Authorization, Accouting||
||s3cfg||Deployment Settings||
||s3gis||GIS Module||
||s3msg||Messaging API||
||s3test|| ||
||s3tools||Tools||
||s3utils||Utilities||
||s3validators||Custom Validators||
||s3vita||Person Finder Toolkit (VITA)||
||s3widgets||Custom UI Widgets||
||s3xrc||Extensible Resource Controller (S3XRC)||
||s3rest||RESTful API (S3XRC)||
||s3crud||RESTful CRUD Methods (S3XRC)||
||s3search||RESTful Search Methods||
||s3export||Resource Export Toolkit (S3XRC)||
||s3import||Resource Import Toolkit (S3XRC)||
||s3model||Data Model Extensions (S3XRC)||
||s3xml||XML Toolkit (S3XML)||

== The s3base Namespace ==

The names of the S3 package (=classes, functions, constants) are defined in {{{modules/s3/__init__.py}}} - all names which are imported in this file are available under the {{{s3base}}} namespace. 

This namespace is imported in {{{models/000_1st_run.py}}}, thus it is available to ''all'' models and controllers - you don't need to import any S3 names separately, and neither do you need to think under which namespace a S3 class or function is available: always simply use the {{{s3base}}} prefix:

{{{
gis = s3base.GIS(...)
resource = s3base.S3Resource(...)
}}}

For convenience, the names of {{{s3utils}}}, {{{s3widgets}}} and {{{s3validators}}} are also imported into the global namespace, so you do not need a namesace prefix to access them:

{{{
mytable.myfield.requires = IS_UTC_DATETIME()
mywidget = S3CheckboxWidget.widget()
}}}

== Extending S3 ==

If you're going to add things to S3, please do it at the right place:

  - Utility functions which are meant to be globally available belong into {{{modules/s3/s3utils.py}}}
  - All other utility functions should either be class methods or should not be globally available
  - New classes should be added to the respective modules
  - New modules should be added as separate files

To make a class, function or constant available in the {{{s3base}}} namespace, you should import it in {{{modules/s3/__init__.py}}}:

{{{
from s3xrc import S3ResourceController
}}}

Note that you need to use the {{{from s3xxx import yyy}}} notation (relative import).

== Importing Modules ==

Any submodule in modules/s3 can import names from any other submodule in modules/s3 by simply {{{from s3xxx import yyy}}}, by relative import:

{{{
from s3xrc import S3ResourceController
}}}

If you use the wildcard:

{{{
from s3xxx import *
}}}

then you have to ensure that the name you want to import is listed in the {{{__all__}}} variable inside the respective {{{s3xxx}}} submodule:

{{{
__all__ = ["MyClass", "MyOtherClass"]
}}}

If {{{__all___}}} is not declared inside a submodule, then all names are imported - but this should be avoided.

You can also import names from other modules in the {{{modules}}} directory, by relative import:

{{{
from ..pyparsing import ParseBaseException
}}}

Note the {{{..}}} before the module path.

== Coding Conventions ==

Please consider our coding conventions when coding S3 extensions:

  - names of top-level functions must be prefixed by {{{s3_}}}, must be all lowercase (no CamelCase!), with words separated by underscores, e.g. {{{s3_my_function}}}
  - names of genuine S3 classes (even if based on web2py classes) must be prefixed by S3, and use CamelCase, e.g. {{{S3ResourceController}}}
  - names of customized web2py classes (which are meant to be used instead of the native web2py class) are ''suffixed'' with S3, e.g. {{{AuthS3}}}
  - constants must be prefixed by S3, all uppercase, with words separated by underscores, e.g. S3_MY_CONSTANT
  - functions inside of classes can be named arbitrarily, however, their names should somehow indicate what they do

  - all modules must have a docstring describing the module, the module author(s), the copyright and license
  - the copyright statement must declare the SSF as copyright holder, and the license must be MIT
  - dependencies can be declared with the {{{@requires:}}} statement

{{{
""" Utilities

    @requires: U{B{I{gluon}} <http://web2py.com>}

    @author: Fran Boon <fran[at]aidiq.com>
    @author: Michael Howden <michael[at]aidiq.com>
    @author: Pradnya Kulkarni

    @copyright: (c) 2010 Sahana Software Foundation
    @license: MIT

    Permission is hereby granted, free of charge, to any person
    obtaining a copy of this software and associated documentation
    files (the "Software"), to deal in the Software without
    restriction, including without limitation the rights to use,
    copy, modify, merge, publish, distribute, sublicense, and/or sell
    copies of the Software, and to permit persons to whom the
    Software is furnished to do so, subject to the following
    conditions:

    The above copyright notice and this permission notice shall be
    included in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
    OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
    WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
    OTHER DEALINGS IN THE SOFTWARE.

"""

}}}


  - all functions - in classes or top-level - must have docstrings explaining what they are supposed to do
  - the docstring should contain an {{{@author: }}} tag if the author differs from the module author
  - you should add your email address, if you want others to contact you with questions or suggestions

{{{
def shn_split_multi_value(value):
    """
    @author: Michael Howden <michael[at]aidiq.com>

    Converts a series of numbers delimited by |, or already in a string into a list

    If value = None, returns []

    """

}}}

  - use {{{@status:}}} to indicate the current status of the implementation
  - use {{{@see:}}} to refer to web pages (e.g. Eden wiki pages)
  - see [http://epydoc.sourceforge.net/manual-fields.html] for more docstring tags