Package babel :: Package messages :: Module extract

# Module extract

Basic infrastructure for extracting localizable messages from source files.

This module defines an extensible system for collecting localizable message strings from a variety of sources. A native extractor for Python source files is builtin, extractors for other sources can be added using very simple plugins.

The main entry points into the extraction functionality are the functions extract_from_dir and extract_from_file.

Functions

`iterator`

extract_from_dir(dirname=`'``/home/asmodai/projects/babel-0.9.5``'`, method_map=`[``(``'``**.py``'``,` `'``python``'``)``]`, options_map=None, keywords=`{``'``N_``'``:` None`,` `'``_``'``:` None`,` `'``dgettext``'``:` `(`2`)``,` `'``dngettext``'``:` `(`2`,` 3`)``,` `...`, comment_tags=`(``)`, callback=None, strip_comment_tags=False)
Extract messages from any source files found in the given directory.

`list`

extract_from_file(method, filename, keywords=`{``'``N_``'``:` None`,` `'``_``'``:` None`,` `'``dgettext``'``:` `(`2`)``,` `'``dngettext``'``:` `(`2`,` 3`)``,` `...`, comment_tags=`(``)`, options=None, strip_comment_tags=False) Extract messages from a specific file. |

`list`

extract(method, fileobj, keywords=`{``'``N_``'``:` None`,` `'``_``'``:` None`,` `'``dgettext``'``:` `(`2`)``,` `'``dngettext``'``:` `(`2`,` 3`)``,` `...`, comment_tags=`(``)`, options=None, strip_comment_tags=False) Extract messages from the given file-like object using the specified extraction method. |

Function Details

### extract_from_dir(dirname=`'``/home/asmodai/projects/babel-0.9.5``'`, method_map=`[``(``'``**.py``'``,` `'``python``'``)``]`, options_map=None, keywords=`{``'``N_``'``:` None`,` `'``_``'``:` None`,` `'``dgettext``'``:` `(`2`)``,` `'``dngettext``'``:` `(`2`,` 3`)``,` `...`, comment_tags=`(``)`, callback=None, strip_comment_tags=False)

Extract messages from any source files found in the given directory.

This function generates tuples of the form:

> `(filename, lineno, message, comments)`

Which extraction method is used per file is determined by the `method_map` parameter, which maps extended glob patterns to extraction method names. For example, the following is the default mapping:

    >>> method_map = [
    ...     ('**.py', 'python')
    ... ]

This basically says that files with the filename extension ".py" at any level inside the directory should be processed by the "python" extraction method. Files that don't match any of the mapping patterns are ignored. See the documentation of the pathmatch function for details on the pattern syntax.

The following extended mapping would also use the "genshi" extraction method on any file in "templates" subdirectory:

    >>> method_map = [
    ...     ('**/templates/**.*', 'genshi'),
    ...     ('**.py', 'python')
    ... ]

The dictionary provided by the optional `options_map` parameter augments these mappings. It uses extended glob patterns as keys, and the values are dictionaries mapping options names to option values (both strings).

The glob patterns of the `options_map` do not necessarily need to be the same as those used in the method mapping. For example, while all files in the `templates` folders in an application may be Genshi applications, the options for those files may differ based on extension:

    >>> options_map = {
    ...     '**/templates/**.txt': {
    ...         'template_class': 'genshi.template:TextTemplate',
    ...         'encoding': 'latin-1'
    ...     },
    ...     '**/templates/**.html': {
    ...         'include_attrs': ''
    ...     }
    ... }

Parameters:
  - `dirname` - the path to the directory to extract messages from
  - `method_map` - a list of `(pattern, method)` tuples that maps of extraction method names to extended glob patterns
  - `options_map` - a dictionary of additional options (optional)
  - `keywords` - a dictionary mapping keywords (i.e. names of functions that should be recognized as translation functions) to tuples that specify which of their arguments contain localizable strings
  - `comment_tags` - a list of tags of translator comments to search for and include in the results
  - `callback` - a function that is called for every file that message are extracted from, just before the extraction itself is performed; the function is passed the filename, the name of the extraction method and and the options dictionary as positional arguments, in that order
  - `strip_comment_tags` - a flag that if set to `True` causes all comment tags to be removed from the collected comments.
Returns: `iterator`
  an iterator over `(filename, lineno, funcname, message)` tuples

See Also: pathmatch

### extract_from_file(method, filename, keywords=`{``'``N_``'``:` None`,` `'``_``'``:` None`,` `'``dgettext``'``:` `(`2`)``,` `'``dngettext``'``:` `(`2`,` 3`)``,` `...`, comment_tags=`(``)`, options=None, strip_comment_tags=False)

Extract messages from a specific file.

This function returns a list of tuples of the form:

> `(lineno, funcname, message)`

Parameters:
  - `filename` - the path to the file to extract messages from
  - `method` - a string specifying the extraction method (.e.g. "python")
  - `keywords` - a dictionary mapping keywords (i.e. names of functions that should be recognized as translation functions) to tuples that specify which of their arguments contain localizable strings
  - `comment_tags` - a list of translator tags to search for and include in the results
  - `strip_comment_tags` - a flag that if set to `True` causes all comment tags to be removed from the collected comments.
  - `options` - a dictionary of additional options (optional)
Returns: `list`
  the list of extracted messages

### extract(method, fileobj, keywords=`{``'``N_``'``:` None`,` `'``_``'``:` None`,` `'``dgettext``'``:` `(`2`)``,` `'``dngettext``'``:` `(`2`,` 3`)``,` `...`, comment_tags=`(``)`, options=None, strip_comment_tags=False)

Extract messages from the given file-like object using the specified extraction method.

This function returns a list of tuples of the form:

> `(lineno, message, comments)`

The implementation dispatches the actual extraction to plugins, based on the value of the `method` parameter.

    >>> source = '''# foo module
    ... def run(argv):
    ...    print _('Hello, world!')
    ... '''

    >>> from StringIO import StringIO
    >>> for message in extract('python', StringIO(source)):
    ...     print message
    (3, u'Hello, world!', [])

Parameters:
  - `method` - a string specifying the extraction method (.e.g. "python"); if this is a simple name, the extraction function will be looked up by entry point; if it is an explicit reference to a function (of the form `package.module:funcname` or `package.module.funcname`), the corresponding function will be imported and used
  - `fileobj` - the file-like object the messages should be extracted from
  - `keywords` - a dictionary mapping keywords (i.e. names of functions that should be recognized as translation functions) to tuples that specify which of their arguments contain localizable strings
  - `comment_tags` - a list of translator tags to search for and include in the results
  - `options` - a dictionary of additional options (optional)
  - `strip_comment_tags` - a flag that if set to `True` causes all comment tags to be removed from the collected comments.
Returns: `list`
  the list of extracted messages
Raises:
  - `ValueError` - if the extraction method is not registered